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Centuries of Human-Driven Change in Salt Marsh Ecosystems
NASA Astrophysics Data System (ADS)
Gedan, K. Bromberg; Silliman, B. R.; Bertness, M. D.
Salt marshes are among the most abundant, fertile, and accessible coastal habitats on earth, and they provide more ecosystem services to coastal populations than any other environment. Since the Middle Ages, humans have manipulated salt marshes at a grand scale, altering species composition, distribution, and ecosystem function. Here, we review historic and contemporary human activities in marsh ecosystemsŚexploitation of plant products; conversion to farmland, salt works, and urban land; introduction of non-native species; alteration of coastal hydrology; and metal and nutrient pollution. Unexpectedly, diverse types of impacts can have a similar consequence, turning salt marsh food webs upside down, dramatically increasing top down control. Of the various impacts, invasive species, runaway consumer effects, and sea level rise represent the greatest threats to salt marsh ecosystems. We conclude that the best way to protect salt marshes and the services they provide is through the integrated approach of ecosystem-based management.
The nitrogen budget of a salt marsh ecosystem
Ivan Valiela; John M. Teal
Salt marshes reduce oxidised nitrogenous compounds to ammonium and paniculate nitrogen and export these reduced forms to coastal waters. The internal demands exceed the net inputs of nitrogen by rain, groundwater flow and fixation, suggesting very active uptake, conversion, release and recycling of nitrogen within a marsh ecosystem. Nitrogen losses are mainly through tidal exchanges and denitrification, and these two
Pyrite: its rapid formation in a salt marsh and its importance in ecosystem metabolism
Pyrite formation in salt-marsh peat occurs more rapidly than is generally thought for any natural system. Pyrite is the major end product of sulfate reduction, and sulfate reduction is the major form of respiration in the salt-marsh ecosystem. When the rapid formation of pyrite is ignored, the rates of sulfate reduction and ecosystem respiration may be grossly underestimated.
Salt Marshes at Chincoteague Island
Salt marshes at Chincoteague Island. The salt marshes that make up Chincoteague Island are important habitat for migrating waterfowl. In addition, they serve an important role in protecting inland ecosystems and communities from oceanic storms....
Mercury in salt marshes ecosystems: Halimione portulacoides as biomonitor
M. Vßlega; A. I. Lilleb°; M. E. Pereira; I. Cańador; A. C. Duarte; M. A. Pardal
Mercury concentrations were quantified in Halimione portulacoides (roots, stems and leaves) as well as in sediments from eight Portuguese estuarine systems, covering seventeen salt marshes with distinct degrees of mercury contamination. The concentration of mercury in the sediments ranged from 0.03 to 17.0?gg?1. The results show that the accumulation of mercury differed according to the organ of the plant examined
NSDL National Science Digital Library
High school level and higher description of Spartina salt marshes with pictures. Page is full of fantastic photographs most featuring a descriptive caption. Topics discussed include zonation, succession, and the intertidal zone. The habitat's associated flora and fauna are discussed. Organisms of particular interest include: Spartina alterniflora, Spartina patens, Geukenzia demissa, Mytilus edulis, Distichlis spicata, Salicornia, Melampus bidentatus, Ilyanassa obsoleta, and Hydrobia totteni.
Salt Marshes at Chincoteague Island
Salt marshes at Chincoteague Island. The salt marshes that make up Chincoteague Island are important habitat for migrating waterfowl. In addition, they serve an important role in protecting inland ecosystems and communities from oceanic storms. Mosquito point can be seen in the background where the ...
Salt Marshes along Little Mosquito Creek
Salt marshes along Little Mosquito Creek of Chincoteague Island. The salt marshes that make up Chincoteague Island are important habitat for migrating waterfowl. In addition, they serve an important role in protecting inland ecosystems and communities from oceanic storms....
Effects of the antifouling compound, Irgarol 1051, on a simulated estuarine salt marsh ecosystem.
DeLorenzo, M E; Pennington, P L; Chung, K W; Finnegan, M C; Fulton, M H
Toxicity effects of the antifouling compound, Irgarol 1051, were examined using a simulated estuarine salt marsh ecosystem. The 35 day mesocosm exposure incorporated tidal flux and contained seawater, sediments, marsh grass, and estuarine biota. Irgarol (10.0 microg/l) caused a significant reduction in phytoplankton biomass and primary productivity. HPLC pigment analysis indicated significant effects of irgarol on both phytoplankton and periphyton community composition, with decreased concentrations of pigments representative of diatom species. There was also a significant decrease in dissolved oxygen levels in the 10.0 microg/l irgarol treatment. Growth of the hard shell clam was significantly reduced in the 1.0 and 10.0 microg/l irgarol treatments. The effects observed occurred at irgarol concentrations greater than those typically measured in the environment. Prolonged exposure, the accumulation of irgarol in sediments, plant, or animal tissues, and the interaction of irgarol with other chemicals in the environment; however, could increase risk. PMID:19015980
We relate plant zonation in salt marshes to key ecosystem services such as erosion control and wildlife habitat. Ten salt marshes in Narragansett Bay, with similar geological bedrock and sea exchange, were identified to examine plant zonation. Sub-watersheds adjacent to the salt ...
Hemigrapsus sanguineus in Long Island salt marshes: experimental evaluation of the interactions between an invasive crab and resident ecosystem engineers
Fournier, Alexa M.; Furman, Bradley T.; Carroll, John M.
The invasive Asian shore crab, Hemigrapsus sanguineus, has recently been observed occupying salt marshes, a novel environment for this crab species. As it invades this new habitat, it is likely to interact with a number of important salt marsh species. To understand the potential effects of H. sanguineus on this ecosystem, interactions between this invasive crab and important salt marsh ecosystem engineers were examined. Laboratory experiments demonstrated competition for burrows between H. sanguineus and the native fiddler crab, Uca pugilator. Results indicate that H. sanguineus is able to displace an established fiddler crab from its burrow. Feeding experiments revealed that the presence of H. sanguineus has a significantly negative impact on the number as well as the biomass of ribbed mussels (Geukensia demissa) consumed by the green crab, Carcinus maenas, although this only occurred at high predator densities. In addition, when both crabs foraged together, there was a significant shift in the size of mussels consumed. These interactions suggests that H. sanguineus may have long-term impacts and wide-ranging negative effects on the saltmarsh ecosystem. PMID:25071995
Chemical and Biological Gradients: Controls on Nitrous Oxide Release in Salt Marsh Ecosystems
Vallino, Joseph J.
was lowest in the cores from sites with high nitrate levels. 8 additional cores were set up in the lab with 4 Sippewissett Marsh, nitrous oxide, nitrate, methionine #12;Reeve 2012 Controls on Nitrous Oxide Release in Salt treatments: a control, a nitrate treatment, a nitrate and methionine treatment, and a nitrous oxide treatment
Flax pond ecosystem study: exchanges of CO/sub 2/ between a salt marsh and the atmosphere
Houghton, R.A.; Woodwell, G.M.
Profiles of CO/sub 2/ concentration, windspeed, and temperature were used in the aerodynamic flux technique to calculate the CO/sub 2/ exchange between a Long Island salt marsh and the atmosphere. Uptake of CO/sub 2/ by the marsh during hours of sunlight and release during the night occurred during all times of the year. The rates of CO/sub 2/ exchange were highest during midsummer, 2.3 g CO/sub 2/.m/sup -2/.h/sup -1/ averaged over the daylight hours of July, and 1.3 g CO/sub 2/.m/sup -2/.h/sup -1/ for both uptake and release. The net 24-h exchange rates followed Spartina growth and senescence during the summer and fall, and photosynthesis of benthic algae during late winter and spring. There was a net uptake of Co/sub 2/ over 24 h by the marsh during all seasons except autumn. The net annual flow of carbon was from the atmosphere to Flax Pond (approx. = 300 g C.m/sup -2/.yr/sup -1/ averaged over the entire marsh ecosystem). This flux was larger than the net exchange of carbon between the marsh and either uplands, sediments, or coastal waters. The net uptake of CO/sub 2/ during summer was less than the net productivity of the vascular plants, indicating that some of the CO/sub 2/ assimilated by the plants came from heterotrophic respiration within the marsh. Nevertheless, respiration by the plants was by far the largest source of CO/sub 2/ from the marsh surface. Nighttime respiration of the ecosystem released a total of approx. = 510 g C.m/sup -2/.yr/sup -1/ to the atmosphere.
Five ecosystem services: water quality maintenance, erosion and flood control, recreation and cultural use, wildlife habitat, and food production were identified from the literature as key services to characterize salt marshes of high integrity. We describe a systems approach to ...
Oregon Salt Marshes: How Blue are They?
Two important ecosystem services of wetlands are carbon sequestration and filtration of nutrients and particulates. We quantified the carbon and nitrogen accumulation rates in salt marshes at 135 plots distributed across eight estuaries located in Oregon, USA. Net carbon and ...
Tidal pumping as a driver of groundwater discharge to a back barrier salt marsh ecosystem
NASA Astrophysics Data System (ADS)
Carter, M. L.; Viso, R. F.; Peterson, R. N.; Hill, J. C.
Submarine groundwater discharge (SGD) typically consists of both terrestrial groundwater and recirculated seawater and has been shown to be a significant pathway of dissolved substances to the coastal zone. The fresh and saline water mixture in the subsurface creates a salinity gradient that can impact biogeochemical processes. Located along the South Atlantic Bight, Georgia's coastline is an approximately 100-mile stretch of complex primary and secondary barrier islands resulting from geologic interactions driven by long-term sea level rise and retreat, accretion, seasonal tidal events, storm overwash, and wave driven erosion. Our study site is located in the Duplin River near Sapelo Island, GA and is part of the Georgia Coastal Ecosystems Long Term Ecosystem Research (GCE-LTER) program. This area is considered mesotidal (2-4m) and tidal pumping may be a dominating process in controlling SGD rates. The Duplin River is connected to the Atlantic Ocean through Doboy Sound to the south. To the north, the river terminates in extensive salt marsh and therefore has no overland freshwater input. Previous studies show a salinity gradient within the Duplin River indicating that SGD must be present as a source of brackish water. To place constraints on SGD processes, we employ a combination of geochemical and geophysical techniques to determine the magnitude of SGD in the Duplin River. Together these techniques permit a more complete understanding of the groundwater system. Three time series stations at the upper, mid and lower reaches of the Duplin River were deployed in June of 2013 to measure groundwater influences during daily and fortnightly tidal cycles. At each station, continuous radon-222 measurements were conducted at 30 minute intervals along with measurements of water level, temperature and conductivity using standard hydrological data loggers. During this period, eight time series resistivity profiles using a 56 electrode (110m long) cable were recorded to provide detailed imagery of fluid interactions at the ground/surface water interface during a tidal cycle. The resistivity profiles are presented as color contoured tomograms representing the shallow aquifer system to depths exceeding 20 meters. Measurements took place during a series of large precipitation events, including immediately before and after a tropical storm, as well as during relatively dry conditions. Taking into account the metrological variability, our initial results indicate that the SGD process is most strongly influenced by tidal pumping. Radon analysis and resistivity measurements reveal strong inverse relationships with water level. Percent difference resistivity models indicate substantial tidally controlled pore fluid flushing and mixing within the shallow aquifer system. These measurements will be further used to construct a water budget within the Duplin River and to delineate the extent of variability in salinity of shallow marsh sediments. In addition, these measurements will provide accurate rates and flow geometries useful as constraints on ongoing reactive transport modeling efforts.
Flax Pond ecosystem study: exchanges of carbon in water between a salt marsh and Long Island Sound
G. M. Woodwell; D. E. Whitney; C. A. S. Hall; R. A. Houghton
Flax Pond, a tidal marsh on the north shore of Long Island, New York, was used to examine the exchanges of carbon in its various forms between a salt marsh and the coastal waters. The marsh removed fine particulate carbon from the tidal water throughout the year; it tended to be a small source of C as total COŌ and
Responses of salt marsh ecosystems to mosquito control management practices along the Atlantic Coast (U.S.A.)
James-Pirri, Mary-Jane; Erwin, R. Michael; Prosser, Diann J.; Taylor, Janith D.
Open marsh water management (OMWM) of salt marshes modifies grid-ditched marshes by creating permanent ponds and radial ditches in the high marsh that reduce mosquito production and enhance fish predation on mosquitoes. It is preferable to using pesticides to control salt marsh mosquito production and is commonly presented as a restoration or habitat enhancement tool for grid-ditched salt marshes. Monitoring of nekton, vegetation, groundwater level, soil salinity, and bird communities before and after OMWM at 11 (six treatment and five reference sites) Atlantic Coast (U.S.A.) salt marshes revealed high variability within and among differing OMWM techniques (ditch-plugging, reengineering of sill ditches, and the creation of ponds and radial ditches). At three marshes, the dominant nekton shifted from fish (primarily Fundulidae species) to shrimp (Palaemonidae species) after manipulations and shrimp density increased at other treatment sites. Vegetation changed at only two sites, one with construction equipment impacts (not desired) and one with a decrease in woody vegetation along existing ditches (desired). One marsh had lower groundwater level and soil salinity, and bird use, although variable, was often unrelated to OMWM manipulations. The potential effects of OMWM manipulations on non-target salt marsh resources need to be carefully considered by resource planners when managing marshes for mosquito control.
Salt marsh geomorphology: Physical and ecological effects on landform Keywords: salt marsh geomorphology; AGU Chapman Conference
Fagherazzi, Sergio
Editorial Salt marsh geomorphology: Physical and ecological effects on landform Keywords: salt marsh geomorphology; AGU Chapman Conference Evidence that the three-dimensional structure of salt marsh, and the ratio of marsh edge:marsh interior have all been shown to affect the distribution and density of salt
Exotic Spartina alterniflora invasion alters ecosystem-atmosphere exchange of CH4 and N2 O and carbon sequestration in a coastal salt marsh in China.
Yuan, Junji; Ding, Weixin; Liu, Deyan; Kang, Hojeong; Freeman, Chris; Xiang, Jian; Lin, Yongxin
Coastal salt marshes are sensitive to global climate change and may play an important role in mitigating global warming. To evaluate the impacts of Spartina alterniflora invasion on global warming potential (GWP) in Chinese coastal areas, we measured CH4 and N2 O fluxes and soil organic carbon sequestration rates along a transect of coastal wetlands in Jiangsu province, China, including open water; bare tidal flat; and invasive S. alterniflora, native Suaeda salsa, and Phragmites australis marshes. Annual CH4 emissions were estimated as 2.81, 4.16, 4.88, 10.79, and 16.98Ākg CH4 Āha(-1) for open water, bare tidal flat, and P. australis, S. salsa, and S. alterniflora marshes, respectively, indicating that S. alterniflora invasion increased CH4 emissions by 57-505%. In contrast, negative N2 O fluxes were found to be significantly and negatively correlated (PĀ<Ā0.001) with net ecosystem CO2 exchange during the growing season in S. alterniflora and P. australis marshes. Annual N2 O emissions were 0.24, 0.38, and 0.56Ākg N2 OĀha(-1) in open water, bare tidal flat and S. salsa marsh, respectively, compared with -0.51Ākg N2 OĀha(-1) for S. alterniflora marsh and -0.25Ākg N2 OĀha(-1) for P. australis marsh. The carbon sequestration rate of S. alterniflora marsh amounted to 3.16 Mg CĀha(-1) Āyr(-1) in the top 100Ācm soil profile, a value that was 2.63- to 8.78-fold higher than in native plant marshes. The estimated GWP was 1.78, -0.60, -4.09, and -1.14ĀMg CO2 eq ha(-1) Āyr(-1) in open water, bare tidal flat, P. australis marsh and S. salsa marsh, respectively, but dropped to -11.30ĀMg CO2 eqĀha(-1) Āyr(-1) in S. alterniflora marsh. Our results indicate that although S. alterniflora invasion stimulates CH4 emissions, it can efficiently mitigate increases in atmospheric CO2 and N2 O along the coast of China. PMID:25367159
Plant Zonation in a Salt Marsh.
ERIC Educational Resources Information Center
Etri, Lawrence R.
The zonation of plants within a salt marsh environment is detailed via illustrations and scientific nomeclature for purposes of encouraging outdoor educators to use the salt marsh environment as a learning laboratory. (JC)
Coastal eutrophication as a driver of salt marsh loss.
Deegan, Linda A; Johnson, David Samuel; Warren, R Scott; Peterson, Bruce J; Fleeger, John W; Fagherazzi, Sergio; Wollheim, Wilfred M
Salt marshes are highly productive coastal wetlands that provide important ecosystem services such as storm protection for coastal cities, nutrient removal and carbon sequestration. Despite protective measures, however, worldwide losses of these ecosystems have accelerated in recent decades. Here we present data from a nine-year whole-ecosystem nutrient-enrichment experiment. Our study demonstrates that nutrient enrichment, a global problem for coastal ecosystems, can be a driver of salt marsh loss. We show that nutrient levels commonly associated with coastal eutrophication increased above-ground leaf biomass, decreased the dense, below-ground biomass of bank-stabilizing roots, and increased microbial decomposition of organic matter. Alterations in these key ecosystem properties reduced geomorphic stability, resulting in creek-bank collapse with significant areas of creek-bank marsh converted to unvegetated mud. This pattern of marsh loss parallels observations for anthropogenically nutrient-enriched marshes worldwide, with creek-edge and bay-edge marsh evolving into mudflats and wider creeks. Our work suggests that current nutrient loading rates to many coastal ecosystems have overwhelmed the capacity of marshes to remove nitrogen without deleterious effects. Projected increases in nitrogen flux to the coast, related to increased fertilizer use required to feed an expanding human population, may rapidly result in a coastal landscape with less marsh, which would reduce the capacity of coastal regions to provide important ecological and economic services. PMID:23075989
Tidal influences on carbon assimilation by a salt marsh
NASA Astrophysics Data System (ADS)
Kathilankal, James C.; Mozdzer, Thomas J.; Fuentes, Jose D.; D'Odorico, Paolo; McGlathery, Karen J.; Zieman, Jay C.
Salt marshes are among the most productive ecosystems on Earth, and play an important role in the global carbon cycle. Net carbon dioxide (CO2) ecosystem exchanges in coastal salt marshes remain poorly investigated. In Spartina alterniflora dominated North American Atlantic coast marshes, the lack of a clear understanding of how Spartina alterniflora responds to flooding limits our current ability to understand and predict salt marsh response to sea-level rise. Here we investigate the processes influencing ecosystem-level carbon exchanges between a S. alterniflora dominated salt marsh on the eastern shore of Virginia and the atmosphere. We examined the impacts of tidal inundation on the marsh-atmosphere carbon exchanges through a combination of eddy covariance measurements and in situ photosynthetic measurements. Maximum daytime carbon fluxes were observed during the middle of the growing season (July and August) and amounted to -10 ?mol CO2 m-2 s-1, and the marsh assimilated 130 gC m-2 during the 2007 growing season. Our study is the first to quantify the effects of tidal inundation on marsh plants, which caused anywhere from 3% to 91% reductions in atmospheric carbon fluxes, with a mean reduction of 46 ▒ 26%, when compared to non-flooded conditions.
The Role of Population-based Diversity on Productivity: Considerations for Restored Spartina alterniflora Salt Marshes
Lee, Courtney T
Plant genetic diversity can augment ecosystem functions in habitats with low plant species diversity. Salt marshes are typically species-depauperate, a condition that is exacerbated when marshes are restored with a single species such as Spartina...
Salt marshes provide water purification as an important ecosystem service in part by storing, transforming and releasing nutrients. This service can be quantified by measuring nutrient fluxes between marshes and surface waters. Many processes drive these fluxes, including photosy...
Spatial and temporal patterns of Lycium carolinianum Walt., the Carolina Wolfberry, in the salt marshes of Aransas National Wildlife Refuge, Texas
Butzler, Rachel Elizabeth
Understanding the salt marsh ecosystem in the Guadalupe Estuary is needed because wetlands in this system support the endangered whooping crane (Grus americana). The marsh plant research and monitoring described herein were based in the salt marshes...
Experimental predator removal causes rapid salt marsh die-off
Bertness, Mark D; Brisson, Caitlin P; Coverdale, Tyler C; Bevil, Matt C; Crotty, Sinead M; Suglia, Elena R
Salt marsh habitat loss to vegetation die-offs has accelerated throughout the western Atlantic in the last four decades. Recent studies have suggested that eutrophication, pollution and/or disease may contribute to the loss of marsh habitat. In light of recent evidence that predators are important determinants of marsh health in New England, we performed a total predator exclusion experiment. Here, we provide the first experimental evidence that predator depletion can cause salt marsh die-off by releasing the herbivorous crab Sesarma reticulatum from predator control. Excluding predators from a marsh ecosystem for a single growing season resulted in a >100% increase in herbivory and a >150% increase in unvegetated bare space compared to plots with predators. Our results confirm that marshes in this region face multiple, potentially synergistic threats. PMID:24766277
Experimental predator removal causes rapid salt marsh die-off.
Bertness, Mark D; Brisson, Caitlin P; Coverdale, Tyler C; Bevil, Matt C; Crotty, Sinead M; Suglia, Elena R
Salt marsh habitat loss to vegetation die-offs has accelerated throughout the western Atlantic in the last four decades. Recent studies have suggested that eutrophication, pollution and/or disease may contribute to the loss of marsh habitat. In light of recent evidence that predators are important determinants of marsh health in New England, we performed a total predator exclusion experiment. Here, we provide the first experimental evidence that predator depletion can cause salt marsh die-off by releasing the herbivorous crab Sesarma reticulatum from predator control. Excluding predators from a marsh ecosystem for a single growing season resulted in a >100% increase in herbivory and a >150% increase in unvegetated bare space compared to plots with predators. Our results confirm that marshes in this region face multiple, potentially synergistic threats. PMID:24766277
Methylmercury production in a Chesapeake Bay salt marsh
NASA Astrophysics Data System (ADS)
Mitchell, Carl P. J.; Gilmour, Cynthia C.
In a detailed study of the biogeochemical factors affecting the methylation of mercury in a Chesapeake Bay salt marsh, we examined relationships between mercury methylation and numerous variables, including sulfate reduction rates, organic carbon mineralization rates, iron and sulfur chemistry, and the character of dissolved organic matter (DOM). Our data show that salt marshes are important sites of de novo methylmercury (MeHg) production in coastal ecosystems. Some of the controls on MeHg production that have been well-described in other ecosystems also impacted MeHg production in this salt marsh, specifically the effect of sulfide accumulation on mercury bioavailability. We observed some novel biogeochemical relationships with Hg(II)-methylation and MeHg accumulation, particularly the positive association of Hg(II)-methylation with zones of microbial iron reduction. On the basis of this relationship, we suggest caution in wetland and groundwater remediation approaches involving iron additions. Aqueous phase Hg complexation appeared to be the dominant control on Hg bioavailability across the marsh sites examined, rather than Hg partitioning behavior. A detailed examination of DOM character in the marsh suggested a strong positive association between Hg(II)-methylation rate constants and increasing DOM molecular weight. Overall, our results indicate that net MeHg production is controlled by a balance between microbial activity and geochemical effects on mercury bioavailability, but that a significant zone of MeHg production can persist in near surface salt marsh soils. Production of MeHg in coastal marshes may negatively impact ecosystems via export to adjacent estuaries or through direct bioaccumulation in birds, fish and amphibians that feed in these highly productive ecosystems.
Wave attenuation over coastal salt marshes under storm surge conditions
NASA Astrophysics Data System (ADS)
M÷ller, Iris; Kudella, Matthias; Rupprecht, Franziska; Spencer, Tom; Paul, Maike; van Wesenbeeck, Bregje K.; Wolters, Guido; Jensen, Kai; Bouma, Tjeerd J.; Miranda-Lange, Martin; Schimmels, Stefan
Coastal communities around the world face an increasing risk from flooding as a result of rising sea level, increasing storminess and land subsidence. Salt marshes can act as natural buffer zones, providing protection from waves during storms. However, the effectiveness of marshes in protecting the coastline during extreme events when water levels are at a maximum and waves are highest is poorly understood. Here we experimentally assess wave dissipation under storm surge conditions in a 300-metre-long wave flume tank that contains a transplanted section of natural salt marsh. We find that the presence of marsh vegetation causes considerable wave attenuation, even when water levels and waves are highest. From a comparison with experiments without vegetation, we estimate that up to 60% of observed wave reduction is attributed to vegetation. We also find that although waves progressively flatten and break vegetation stems and thereby reduce dissipation, the marsh substrate remained stable and resistant to surface erosion under all conditions. The effectiveness of storm wave dissipation and the resilience of tidal marshes even at extreme conditions suggest that salt marsh ecosystems can be a valuable component of coastal protection schemes.
What's the Use of a Salt Marsh?
ERIC Educational Resources Information Center
Van Raalte, Charlene
Summarizes information about salt marshes, including descriptions of their development and structure, details of their values in terms of commercial fishing, stabilization of coastal zones, "reclamation" for grazing and cropfields, recreation and aesthetics. (CS)
US Army Corps of Engineers
of the aquatic ecosystem limits habitat suitability for many species of fish and wildlife. #12;The recommendedMARSH LAKE, APPLETON, MINNESOTA ECOSYSTEM RESTORATION PROJECT 27 SEPTEMBER 2011 ABSTRACT habitat, eliminating winter oxygen refuge for carp and providing for ecosystem connectivity. The natural
The dynamics of bottom¢up and top¢down control in a New England salt marsh
N. M. Sala; M. D. Bertness; B. R. Silliman
Traditionally, salt marsh ecosystems were thought to be controlled exclusively by bottomup processes. Recently, this paradigm has shifted to include topdown control as an additional primary factor regulating salt-marsh community structure. The most recent research on consumer impacts in southern US marshes has shown that topdown forces often interact with biotic and abiotic factors, such as secondary fungal infection in
Mobile dunes and eroding salt marshes
NASA Astrophysics Data System (ADS)
Neuhaus, R.
The paper deals with general outlines of salt marsh and dune vegetation in the Ellenbogen and Listland area on Sylt (Schleswig-Holstein, FRG). The composition of current salt marsh vegetation is considered to be mainly the result of a long-lasting process of tidal inundation, grazing, and a permanent influence of groundwater seepage from the surrounding dunes. The lower salt marsh communities have shown constancy for 67 years, due to the effect of heavy grazing. The mid-upper salt marsh communities demonstrated a succession from a Puccinellia maritima-dominated community of the lower marsh to a Juncus gerardii-dominated community of the mid-upper salt marsh, which may be due to the transport of sand Ś over a short time Ś on the surface of the marsh. The area covered by plant communities of annuals below Mean High Water (MHW) seemed to diminish. Salt marsh soils, especially of the mid-upper marsh, indicate sandy layers resulting from sand drift of the dunes. Dry and wet successional series of the dunes in the Listland/Ellenbogen area both show grassy stages shifting to dwarf shrubs as final stages. White primary dunes can only be found on the accreting shoreline of the Ellenbogen, which is also grazed by sheep; vegetation cover therefore remains dominated by grasses, mosses and lichens. Three mobile dunes (as the most prominent features of this landscape) have been left unaffected by seeding and planting by local authorities. Grazing is considered to be an inadequate tool in nature conservation as long as natural processes are to prevail in the landscape as major determinants.
Coastal Wetland Deterioration, Climate Change and Nutrient Inputs in California and Southern New England Salt Marsh
Coastal salt marshes provide a wide variety of ecosystem services, including habitat for protected vertebrates and ecologically valuable invertebrate fauna, flood protection, and improvements in water quality for adjacent marine and estuarine environments. Here, we consider the i...
Carbon and Nitrogen Accumulation Rates in Salt Marshes in Oregon, USA
Two important ecosystem services of wetlands are carbon sequestration and filtration of nutrients and particulates. We quantified the carbon and nitrogen accumulation rates in salt marshes at 135 plots distributed across eight estuaries located in Oregon, USA. Net carbon and ...
Coastal salt marshes as global methyl halide sources from determinations of intrinsic production by marsh plants
NASA Astrophysics Data System (ADS)
Manley, Steven L.; Wang, Nun-Yii; Walser, Maggie L.; Cicerone, Ralph J.
Emissions of CH3Cl, CH3Br and CH3I were measured biweekly for 12- to 24-month periods between March 2002 and March 2005 from monospecific stands of four dominant southern California coastal salt marsh plants. These measurements revealed large inherent differences between species and more detailed patterns of seasonal production than previously reported. Marsh plants displayed intrinsic abilities to produce methyl halides. Salt marsh plants produced 92% of CH3Cl and 90% of CH3Br emitted and only 41% of the emitted CH3I. Unvegetated areas emitted 7.9% of CH3Cl, 9.9% CH3Br, and 59% of the emitted CH3I. The accuracy of the estimated methyl halide emissions from a coastal marsh and probably other ecosystems can be dramatically improved with increasing the number of species being measured and including emission from barren (mudflats and soil) areas. Estimates of global salt marsh emissions based on vegetated and barren area are 130, 21, 5.5 (mg m-2 yr-1) for CH3Cl, CH3Br, and CH3I, respectively, or 1.2, 3.9, and 0.8% of total global fluxes of these gases.
Mercury volatilization from salt marsh sediments
Lora M. Smith; John R. Reinfelder
In situ volatilization fluxes of gaseous elemental mercury, Hg(0), were estimated for tidally exposed salt marsh sediments in the summer at the urban\\/industrial Secaucus High School Marsh, New Jersey Meadowlands (Secaucus, New Jersey) and in the early autumn at a regional background site in the Great Bay estuary (Tuckerton, New Jersey). Estimated daytime sediment-air mercury volatilization fluxes at the Secaucus
Land use and anthropogenic activities in watersheds affect biological, chemical, and physical conditions in streams and receiving coastal salt marshes. Our objective was to compare indicators of stream and riparian condition with analogous indicators of the coastal salt marshes...
Land use and anthropogenic activities in watersheds affect biological, chemical, and physical conditions in streams and receiving coastal salt marshes. Our objective was to compare indicators of stream and riparian condition with analogous indicators of the coastal salt marshes i...
Land use and anthropogenic activities in watersheds affect biological, chemical, and physical conditions in streams and receiving coastal salt marshes. Our objective was to compare indicators of stream and riparian condition with analogous indicators of the coastal salt marshes i...
Habitat Function of a Restored Salt Marsh: Post-Larval Gulf Killifish as a Sentinel
Successful marsh restoration requires recreating conditions to ensure proper ecosystem function. One approach to monitor restoration success is using a sentinel species as a proxy integrator of salt marsh function. The gulf killifish (Fundulus grandis, Baird and Girard) is a goo...
Recent Trends in Bird Abundance on Rhode Island Salt Marshes
Salt marsh habitat is under pressure from development on the landward side, and sea level rise from the seaward side. The resulting loss of habitat is potentially disastrous for salt marsh dependent species. To assess the population status of three species of salt marsh dependent...
New York State Salt Marsh Restoration and Monitoring Guidelines
#12;New York State Salt Marsh Restoration and Monitoring Guidelines prepared by: Nancy L. Niedowski;The Salt Marsh Restoration and Monitoring Guidelines were prepared under the National OceanicState,Division of CoastalResources,41 State Street,Albany, New York 12231. December 2000 #12;PREFACE All salt marsh
Factors controlling dimethylsulfide emission from salt marshes
NASA Technical Reports Server (NTRS)
Dacey, John W. H.; Wakeham, S. G.; Howes, B. L.
The factors that control the emission of methylated gases from salt marshes are being studied. Research focusses on dimethylsulfide (DMS) formation and the mechanism of DMS and CH4 emission to the atmosphere. The approach is to consider the plants as valves regulating the emission of methylated gases to the atmosphere with the goal of developing appropriate methods for emission measurement. In the case of CH4, the sediment is the source and transport to the atmosphere occurs primarily through the internal gas spaces in the plants. The source of DMS appears to be dimethyl sulfoniopropionate (DMSP) which may play a role in osmoregulation in plant tissues. Concentrations of DMSP in leaves are typically several-fold higher than in roots and rhizomes. Even so, the large below ground biomass of this plant means that 2/3 of the DMSP in the ecosystem is below ground on the aerial basis. Upon introduction to sediment water, DMSP rapidly decomposes to DMS and acrylic acid. The solubility of a gas (its equilibrium vapor pressure) is a fundamental aspect of gas exchange kinetics. The first comprehensive study was conducted of DMS solubility in freshwater and seawater. Data suggest that the Setchenow relation holds for H at intermediate salinities collected. These data support the concept that the concentration of DMS in the atmosphere is far from equilibrium with seawater.
Vegetable Oil Spills On Salt Marshes
Stephen M. Mudge; Ian D. Goodchild; Matthew Wheeler
Following the wreck of the M.V. Kimya during which 1500 tonnes of sunflower oil was spilled, sandy sediments bound together with sunflower oil were discovered on the beach. These are still present 2Į years later. Sunflower and linseed oil were applied to salt marsh sediments to reproduce potential spills. Cores were taken and the vertical migration and degradation rates determined.
Early Salt-Marsh Development, an Example of a Turing Instability?
NASA Astrophysics Data System (ADS)
van de Koppel, J.
In the past decades, regular spatial patterns have been described in a wide range of ecosystems, ranging from arid lands to boreal peat lands. Pattern formation mechanisms in many of these ecosystems are caused by scale-dependent interactions between organisms and geophysical processes, causing facilitation between organisms at small spatial scale, but inhibition at larger spatial scales. This conforms to the activation-inhibition principle laid out by Alan Turing in 1953. We present a combination of experimental and modeling studies on early salt-marsh development that indicate that similar scale-dependent interactions determine the establishment of salt-marsh vegetation and early geomorphological development of the marsh. Based on these studies, we argue that the early development of salt-marsh ecosystems is characterized by a Turing instability, placed into a complex landscape setting.
Microbial Community Analysis of a Coastal Salt Marsh Affected by the Deepwater Horizon Oil Spill
Beazley, Melanie J.; Martinez, Robert J.; Rajan, Suja; Powell, Jessica; Piceno, Yvette M.; Tom, Lauren M.; Andersen, Gary L.; Hazen, Terry C.; Van Nostrand, Joy D.; Zhou, Jizhong; Mortazavi, Behzad; Sobecky, Patricia A.
Coastal salt marshes are highly sensitive wetland ecosystems that can sustain long-term impacts from anthropogenic events such as oil spills. In this study, we examined the microbial communities of a Gulf of Mexico coastal salt marsh during and after the influx of petroleum hydrocarbons following the Deepwater Horizon oil spill. Total hydrocarbon concentrations in salt marsh sediments were highest in June and July 2010 and decreased in September 2010. Coupled PhyloChip and GeoChip microarray analyses demonstrated that the microbial community structure and function of the extant salt marsh hydrocarbon-degrading microbial populations changed significantly during the study. The relative richness and abundance of phyla containing previously described hydrocarbon-degrading bacteria (Proteobacteria, Bacteroidetes, and Actinobacteria) increased in hydrocarbon-contaminated sediments and then decreased once hydrocarbons were below detection. Firmicutes, however, continued to increase in relative richness and abundance after hydrocarbon concentrations were below detection. Functional genes involved in hydrocarbon degradation were enriched in hydrocarbon-contaminated sediments then declined significantly (p<0.05) once hydrocarbon concentrations decreased. A greater decrease in hydrocarbon concentrations among marsh grass sediments compared to inlet sediments (lacking marsh grass) suggests that the marsh rhizosphere microbial communities could also be contributing to hydrocarbon degradation. The results of this study provide a comprehensive view of microbial community structural and functional dynamics within perturbed salt marsh ecosystems. PMID:22815990
Evaluation of salt marsh hydrology using radium as a tracer
M. S. Bollinger; W. S. Moore
Radium isotopes provide unique and important information concerning water exchange in a salt marsh-tidal creek system. Seasonal radium data collected over five tidal cycles from a creek draining a South Carolina salt marsh, radium and thorium data from the adjacent marsh sediments, and interstitial water radium data from the drainage basin are modeled to yield residence times of water in
[Deposition and burial of organic carbon in coastal salt marsh: research progress].
Cao, Lei; Song, Jin-Ming; Li, Xue-Gang; Yuan, Hua-Mao; Li, Ning; Duan, Li-Qin
Coastal salt marsh has higher potential of carbon sequestration, playing an important role in mitigating global warming, while coastal saline soil is the largest organic carbon pool in the coastal salt marsh carbon budget. To study the carbon deposition and burial in this soil is of significance for clearly understanding the carbon budget of coastal salt marsh. This paper summarized the research progress on the deposition and burial of organic carbon in coastal salt marsh from the aspects of the sources of coastal salt marsh soil organic carbon, soil organic carbon storage and deposition rate, burial mechanisms of soil organic carbon, and the relationships between the carbon sequestration in coastal salt marsh and the global climate change. Some suggestions for the future related researches were put forward: 1) to further study the underlying factors that control the variability of carbon storage in coastal salt marsh, 2) to standardize the methods for measuring the carbon storage and the deposition and burial rates of organic carbon in coastal salt marsh, 3) to quantify the lateral exchange of carbon flux between coastal salt marsh and adjacent ecosystems under the effects of tide, and 4) to approach whether the effects of global warming and the increased productivity could compensate for the increase of the organic carbon decomposition rate resulted from sediment respiration. To make clear the driving factors determining the variability of carbon sequestration rate and how the organic carbon storage is affected by climate change and anthropogenic activities would be helpful to improve the carbon sequestration capacity of coastal salt marshes in China. PMID:24175538
Plant invasion impacts on the gross and net primary production of the salt marsh on eastern coast of China: Insights from leaf to ecosystem
NASA Astrophysics Data System (ADS)
Ge, Zhen-Ming; Guo, Hai-Qiang; Zhao, Bin; Zhang, Li-Quan
exotic Spartina alterniflora from North America has been rapidly invading the entire Chinese coast, while the impacts of plant invasion on the gross (GPP) and net primary production (NPP) of the coastal salt marshes were less known. In this study, we investigated the photosynthetic performance, leaf characteristics, and primary production of the exotic C4 grass and the dominant native C3 grass (Phragmites australis) in two marsh mixtures (equipped with eddy covariance systems) in the Yangtze Estuary. The light-saturated photosynthetic rate and annual peak leaf area index (LAI) of S. alterniflora was higher than that of P. australis throughout the growing season. The leaf nitrogen content of P. australis declined sharper during the latter growing season than that of S. alterniflora. The leaf-to-canopy production model with species-specific (C3 and C4 types) parameterizations could reasonably simulate the daily trends and annual GPP amount against the 3 year flux measurements from 2005 to 2007, and the modeled NPP agreed with biomass measurements from the two species during 2012. The percentage contributions of GPP between S. alterniflora and P. australis were on average 5.82:1 and 2.91:1 in the two mixtures, respectively. The annual NPP amounts from S. alterniflora were higher by approximately 1.6 times than that from P. australis. Our results suggested that higher photosynthesis efficiency, higher LAI, and longer growing season resulted in greater GPP and NPP in the exotic species relative to the native species. The rapid expansion rate of S. alterniflora further made it the leading contributor of primary production in the salt marsh.
Response of a salt marsh microbial community to metal contamination
NASA Astrophysics Data System (ADS)
Mucha, Ana P.; Teixeira, Catarina; Reis, Izabela; MagalhŃes, Catarina; Bordalo, Adriano A.; Almeida, C. Marisa R.
Salt marshes are important sinks for contaminants, namely metals that tend to accumulate around plant roots and could eventually be taken up in a process known as phytoremediation. On the other hand, microbial communities display important roles in the salt marsh ecosystems, such as recycling of nutrients and/or degradation of organic contaminants. Thus, plants can benefit from the microbial activity in the phytoremediation process. Nevertheless, above certain levels, metals are known to be toxic to microorganisms, fact that can eventually compromise their ecological functions. In this vein, the aim of present study was to investigate, in the laboratory, the effect of selected metals (Cd, Cu and Pb) on the microbial communities associated to the roots of two salt marsh plants. Sediments colonized by Juncus maritimus and Phragmites australis were collected in the River Lima estuary (NW Portugal), and spiked with each of the metals at three different Effects Range-Median (ERM) concentrations (1, 10ū, 50ū), being ERM the sediment quality guideline that indicates the concentration above which adverse biological effects may frequently occur. Spiked sediments were incubated with a nutritive saline solution, being left in the dark under constant agitation for 7 days. The results showed that, despite the initial sediments colonized by J. maritimus and P. australis displayed significant (p < 0.05) differences in terms of microbial community structure (evaluated by ARISA), they presented similar microbial abundances (estimated by DAPI). Also, in terms of microbial abundance, both sediments showed a similar response to metal addition, with a decrease in number of cells only observed for the higher addition of Cu. Nevertheless, both Cu and Pb, at intermediate metals levels promote a shift in the microbial community structure, with possibly effect on the ecological function of these microbial communities in salt marshes. These changes may affect plants phytoremediation potential and further work on this subject is in need.
Consequences of Climate Change, Eutrophication, and Other Anthropogenic Impacts to Coastal Salt Marshes: Multiple Stressors Reduce Resiliency and Sustainability
Coastal salt marshes provide a wide variety of ecosystem services, including habitat for protected vertebrates and ecologically valuable invertebrate fauna, flood protection, and improvements in water quality for adjacent marine and estuarine environments. Here, we consider the ...
Nutrient enrichment and the role of salt marshes in the Tagus estuary (Portugal)
NASA Astrophysics Data System (ADS)
Simas, T. C.; Ferreira, J. G.
Eutrophication is one of the most common impacts of nutrient enrichment on coastal ecosystems. Since there is a wide ecosystem response variety in scale, intensity and impact to nutrient enrichment, the loading required to produce eutrophication symptoms to each system is also variable. In estuaries and coastal zones salt marsh primary producers have received less attention, mainly because salt marsh dominated systems are considered less sensitive to nutrient enrichment and, for that reason, their response is slower and more difficult to quantify. Salt marshes have been considered as major attenuators of the effects of nitrogen enrichment in several coastal systems, and are indicated as a measure of the system susceptibility to nutrient enrichment. The main goal of the present work is to discuss the role of salt marsh vegetation in the nutrient dynamics of coastal systems and in the nutrient enrichment process. For these purposes salt marsh vegetation growth in the Tagus estuary is described through a mathematical model which includes the simulation of the nutrient dynamics through the sediment-water interface and the uptake kinetics by the vascular plants. An analysis of the role of salt marsh vegetation on the nutrient dynamics of the Tagus estuary is carried out through the discussion of the model results and comparison with data obtained for other primary producers in the system. The results indicate that C 4 salt marsh plants have the highest productivity, followed by seaweeds. The total net production of salt marsh plants and is about 12,600 ton C yr -1, accounting for 25% of the total primary production within the system.
Controls on resilience and stability in a sediment-subsidized salt marsh.
Stagg, Camille L; Mendelssohn, Irving A
Although the concept of self-design is frequently employed in restoration, reestablishment of primary physical drivers does not always result in a restored ecosystem having the desired ecological functions that support system resilience and stability. We investigated the use of a primary environmental driver in coastal salt marshes, sediment availability, as a means of promoting the resilience and stability of submerging deltaic salt marshes, which are rapidly subsiding due to natural and human-induced processes. We conducted a disturbance-recovery experiment across a gradient of sediment slurry addition to assess the roles of sediment elevation and soil physico-chemical characteristics on vegetation resilience and stability in two restored salt marshes of differing age (a 15-year-old site and a 5-year-old site). Salt marshes that received moderate intensities of sediment slurry addition with elevations at the mid to high intertidal zone (2-11 cm above local mean sea level; MSL) were more resilient than natural marshes. The primary regulator of enhanced resilience and stability in the restored marshes was the alleviation of flooding stress observed in the natural, unsubsidized marsh. However, stability reached a sediment addition threshold, at an elevation of 11 cm above MSL, with decreasing stability in marshes above this elevation. Declines in resilience and stability above the sediment addition threshold were principally influenced by relatively dry conditions that resulted from insufficient and infrequent flooding at high elevations. Although the older restored marsh has subsided over time, areas receiving too much sediment still had limited stability 15 years later, emphasizing the importance of applying the appropriate amount of sediment to the marsh. In contrast, treated marshes with elevations 2-11 cm above MSL were still more resilient than the natural marsh 15 years after restoration, illustrating that when performed correctly, sediment slurry addition can be a sustainable restoration technique. PMID:21830714
Remote sensing of wetland conditions in West Coast salt marshes
NASA Astrophysics Data System (ADS)
Ustin, Susan L.; Lay, Mui C.; Li, Lin
The objective of the PEEIR (Pacific Estuarine Ecosystem Indicator Research Consortium) program is to develop new indicators for assessing wetland health or condition. As part of PEEIR program we are investigating the use of imaging spectrometry to map and characterize marsh vegetation of several estuarine systems in California. We obtained airborne Advanced Visible Infrared Imaging Spectrometer (AVIRIS) data, an instrument which measures a detailed reflectance spectrum (400-2500nm) for each pixel, over paired tidal marshes, having either a history of exposure to pollution or no known exposure. AVIRIS image data was analyzed based on comparison to field measurements and reflectance changes measured in hydroponic experiments. We report leaf and canopy reflectance measurements of several common plant species of Pacific coast salt marshes exposed to different concentrations of heavy metals (Cd, V) and crude oil contaminants. Species exhibited differential sensitivities to specific contaminants, however in general, Salicornia virginica, the most salt tolerant species and the dominant species in these wetlands (70-90% cover) was most sensitive to metal and petroleum contaminants. Field measurements of canopy reflectance, biomass and vegetation structure were acquired across GPS-located transects at each field site. The AVIRIS data were calibrated to surface reflectance using the FLAASH radiative transfer code and geometrically registered to coordinates using the 1m USGS digital orthophoto quads. AVIRIS results show spatial patterns of plant stress indicators (e.g., reduced chlorophyll and water contents) are consistent with known patterns of contamination in these tidal wetlands.
Salt marshes in the silica budget of the North Sea
NASA Astrophysics Data System (ADS)
Moosdorf, Nils; Weiss, Andreas; M³ller, Frauke; Lauerwald, Ronny; Hartmann, Jens; Worrall, Fred
Local scale studies reported the silica recycling of salt marshes to substantially attenuate the dissolved silica (DSi) limitation in coastal waters during summer. To assess the importance of salt marshes in the silica budget of the North Sea, we extrapolate reported DSi exports by local scale studies to salt marsh areas adjacent to the North Sea. The resulting annual average contribution of salt marshes to the DSi budget of the North Sea is estimated to 0.8% of the annual river DSi export. During summer, this contribution may reach 2.4%. Thus, salt marshes likely impact the annual dissolved silica budget of the North Sea only weakly. However, for regions with favorable geographic conditions of low river DSi exports and large marsh areas, salt marsh DSi exports may substantially contribute to coastal DSi budgets. In the English Channel, salt marsh DSi exports are estimated to 16% of river DSi export in summer. However, the low data density calls for additional field research to improve extrapolations and the evaluation of the contribution of salt marsh DSi export to the coastal DSi budgets.
On salt marsh vegetation in North Korea
Ji?Ē Kolbek; Ji?Ē Dostßlek; Ivan JarolĒmek; Ivan Ostr²; Li Sek-Ha
The salt marsh vegetation on the west coast of North Korea was studied by the method of the Z³rich-Montpellier school. The\\u000a following communities were distinguished:Suaedetum japonicae, Scirpetum iseensis, Artemisietum fukudo, and the following were described as new:Triglochini maritimae-Phragmitetum communis, Artemisio capillaris-Salsoletum komarovii andSalsolo komarovii-Rosetum rugosae. The phytocoenological material was also analysed by means of numerical techniques.\\u000a \\u000a The population density ofSuaeda
Land use and anthropogenic activities in watersheds affect biological, chemical, and physical conditions in streams and receiving coastal salt marshes. Our objective is to compare indicators of stream condition and riparian vegetation with analagous indicators of the coastal salt...
Factors controlling emissions of dimethylsulphide from salt marshes
NASA Technical Reports Server (NTRS)
Dacey, John W. H.; Wakeham, Stuart G.; King, Gary M.
Salt marshes are presently identified as systems exhibiting high area-specific sulfur emission in the form of dimethylsulfide (DMS) and H2S, with the former predominating in vegetated areas of the marshes. Attention is presently given to the distribution of DMS in salt marshes; it is found that this compound primarily arises from physiological processes in the leaves of higher plants, especially the grass species Spartina alterniflora. Uncertainties associated with DMS emission measurements are considered.
Methylmercury production in a Chesapeake Bay salt marsh
Carl P. J. Mitchell; Cynthia C. Gilmour
In a detailed study of the biogeochemical factors affecting the methylation of mercury in a Chesapeake Bay salt marsh, we examined relationships between mercury methylation and numerous variables, including sulfate reduction rates, organic carbon mineralization rates, iron and sulfur chemistry, and the character of dissolved organic matter (DOM). Our data show that salt marshes are important sites of de novo
Pettaquamscutt Cove Salt Marsh: Environmental Conditions and Historical Ecological Change
Using historic air photos and U.S. Coast Survey maps, historic vegetation changes were identified. Using surveys of vegetation and elevation, we measure elevation of Narrow River salt marshes, and compare it with other salt marshes in Rhode Island and neighboring states. Water ...
A trophic cascade regulates salt marsh primary production
Bertness, Mark D.
(bottom-up forces) and consumers (top-down forces) in controlling plant growth. Strong consumer control, are also susceptible to cascading consumer effects. Western Atlantic salt marshes dominated by vascular). Early studies in North American salt marshes concluded that plant┬Łherbivore interactions were of little
Impacts of Multiple Stressors on Southern New England Salt Marshes
In the Northeastern U.S., salt marsh area is in decline. Low sediment supply combined with regionally high rates of sea level rise mean that future salt marsh survival depends primarily on biomass production and organic matter accumulation, which are impacted by high nutrient lo...
Threats to Marsh Resources and Mitigation
Salt marshes inhabit low-energy, intertidal shorelines worldwide and are among the most abundant and productive coastal ecosystems. Salt-marsh ecosystems provide a wide array of benefits to coastal populations, including shoreline protection, fishery support, water quality improv...
Large methyl halide emissions from south Texas salt marshes
NASA Astrophysics Data System (ADS)
Rhew, R. C.; Whelan, M. E.; Min, D.-H.
Coastal salt marshes are natural sources of methyl chloride (CH3Cl) and methyl bromide (CH3Br) to the atmosphere, but measured emission rates vary widely by geography. Here we report large methyl halide fluxes from subtropical salt marshes of south Texas. Sites with the halophytic plant, Batis maritima, emitted methyl halides at rates that are orders of magnitude greater than sites containing other vascular plants or macroalgae. B. maritima emissions were generally highest at midday; however, diurnal variability was more pronounced for CH3Br than CH3Cl, and surprisingly high nighttime CH3Cl fluxes were observed in July. Seasonal and intra-site variability were large, even taking into account biomass differences. Overall, these subtropical salt marsh sites show much higher emission rates than temperate salt marshes at similar times of the year, supporting the contention that low-latitude salt marshes are significant sources of CH3Cl and CH3Br.
Large methyl halide emissions from south Texas salt marshes
NASA Astrophysics Data System (ADS)
Rhew, R. C.; Whelan, M. E.; Min, D.-H.
Coastal salt marshes are natural sources of methyl chloride (CH3Cl) and methyl bromide (CH3Br) to the atmosphere, but measured emission rates vary widely by geography. Here we report large methyl halide fluxes from subtropical salt marshes of south Texas. Sites with the halophytic plant, Batis maritima, emitted methyl halides at rates that are orders of magnitude greater than sites containing other vascular plants or macroalgae. B. maritima emissions were generally highest at midday; however, diurnal variability was more pronounced for CH3Br than CH3Cl, and surprisingly high nighttime CH3Cl fluxes were observed in July. Seasonal and intra-site variability were large, even taking into account biomass differences. Overall, these subtropical salt marsh sites show much higher emission rates than temperate salt marshes at similar times of the year, supporting the contention that low-latitude salt marshes are significant sources of CH3Cl and CH3Br.
Hydrologic modeling as a predictive basis for ecological restoration of salt marshes
Roman, C.T.; Garvine, R.W.; Portnoy, J.W.
Roads, bridges, causeways, impoundments, and dikes in the coastal zone often restrict tidal flow to salt marsh ecosystems. A dike with tide control structures, located at the mouth of the Herring River salt marsh estuarine system (Wellfleet, Massachusetts) since 1908, has effectively restricted tidal exchange, causing changes in marsh vegetation composition, degraded water quality, and reduced abundance of fish and macroinvertebrate communities. Restoration of this estuary by reintroduction of tidal exchange is a feasible management alternative. However, restoration efforts must proceed with caution as residential dwellings and a golf course are located immediately adjacent to and in places within the tidal wetland. A numerical model was developed to predict tide height levels for numerous alternative openings through the Herring River dike. Given these model predictions and knowledge of elevations of flood-prone areas, it becomes possible to make responsible decisions regarding restoration. Moreover, tidal flooding elevations relative to the wetland surface must be known to predict optimum conditions for ecological recovery. The tide height model has a universal role, as demonstrated by successful application at a nearby salt marsh restoration site in Provincetown, Massachusetts. Salt marsh restoration is a valuable management tool toward maintaining and enhancing coastal zone habitat diversity. The tide height model presented in this paper will enable both scientists and resource professionals to assign a degree of predictability when designing salt marsh restoration programs.
Fresh and saltwater ecosystems have customarily been assessed separately. By taking a watershed approach, we are exploring the linkages between stream conditions, the biotic integrity of coastal salt marshes, and land use. Watersheds provide a pathway for point and nonpoint pollu...
The integrity of coastal salt marshes can be determined from the extent to which they provide key ecosystem services: food and habitat for fish and wildlife, good water quality, erosion and flood control, and recreation and cultural use. An outline of a new approach for linking e...
Indirect Human Impacts Reverse Centuries of Carbon Sequestration and Salt Marsh Accretion
Coverdale, Tyler C.; Brisson, Caitlin P.; Young, Eric W.; Yin, Stephanie F.; Donnelly, Jeffrey P.; Bertness, Mark D.
Direct and indirect human impacts on coastal ecosystems have increased over the last several centuries, leading to unprecedented degradation of coastal habitats and loss of ecological services. Here we document a two-century temporal disparity between salt marsh accretion and subsequent loss to indirect human impacts. Field surveys, manipulative experiments and GIS analyses reveal that crab burrowing weakens the marsh peat base and facilitates further burrowing, leading to bank calving, disruption of marsh accretion, and a loss of over two centuries of sequestered carbon from the marsh edge in only three decades. Analogous temporal disparities exist in other systems and are a largely unrecognized obstacle in attaining sustainable ecosystem services in an increasingly human impacted world. In light of the growing threat of indirect impacts worldwide and despite uncertainties in the fate of lost carbon, we suggest that estimates of carbon emissions based only on direct human impacts may significantly underestimate total anthropogenic carbon emissions. PMID:24675669
Indirect human impacts reverse centuries of carbon sequestration and salt marsh accretion.
Coverdale, Tyler C; Brisson, Caitlin P; Young, Eric W; Yin, Stephanie F; Donnelly, Jeffrey P; Bertness, Mark D
Direct and indirect human impacts on coastal ecosystems have increased over the last several centuries, leading to unprecedented degradation of coastal habitats and loss of ecological services. Here we document a two-century temporal disparity between salt marsh accretion and subsequent loss to indirect human impacts. Field surveys, manipulative experiments and GIS analyses reveal that crab burrowing weakens the marsh peat base and facilitates further burrowing, leading to bank calving, disruption of marsh accretion, and a loss of over two centuries of sequestered carbon from the marsh edge in only three decades. Analogous temporal disparities exist in other systems and are a largely unrecognized obstacle in attaining sustainable ecosystem services in an increasingly human impacted world. In light of the growing threat of indirect impacts worldwide and despite uncertainties in the fate of lost carbon, we suggest that estimates of carbon emissions based only on direct human impacts may significantly underestimate total anthropogenic carbon emissions. PMID:24675669
Development of Salt Marsh Monitoring Methodology Using Remote Sensing and GIS
Wang, Y.Q. "Yeqiao"
Development of Salt Marsh Monitoring Methodology Using Remote Sensing and GIS Y.Q. Wang, PI://www.ltrs.uri.edu #12;New Satellite Data in Salt Marsh Change Monitoring Given that salt marsh monitoring requires update the salt marsh maps are necessary. Recent development of high spatial resolution satellite remote
Salt Marsh Sediment Biogeochemical Response to the BP Blowout.
Mills, Calista G; McNeal, Karen S
The impact of the blowout on salt marshes was investigated by observing the biogeochemistry in salt marsh sediments along the Gulf Coast. High sulfide levels due to hydrocarbon loading, increased microbial activity, and microbial community shifts can lead to plant browning and mortality. Sediment biogeochemical processes that degrade enriched carbon pools through sulfate reduction are primarily responsible for the biodegradation of spilled hydrocarbons. An assessment of the impact of contamination on salt marshes at Skiff Island, LA, and Cat Island, Marsh Point, and Saltpan Island, MS, was achieved through sediment electrode profiling, microbial community profiling, and quantification of hydrocarbon contamination, which captured the spatial sedimentary biogeochemical response that affects salt marsh productivity. At western locations (Skiff and Cat Islands), total petroleum hydrocarbons (TPHs) ranged from 2183 to 2996 mg kg, which was more than double the TPH concentration observed at eastern locales. At eastern study locations (e.g., Marsh Point), sedimentary pore-water HS concentrations were higher (maximum value = 231 mg L) and detected further up in the sediment column than at western locales (e.g., Skiff Island). Similarly, anaerobic and aerobic microbial activity, as measured by C substrate utilization profiles and well-color development, was as high or higher at eastern locations as compared with western locations. These results indicate that other factors besides location or degree of contamination, perhaps sedimentary dynamics and physical processes specific to each marsh, should be considered when determining salt marsh response to hydrocarbon contamination. PMID:25603266
Methane flux from coastal salt marshes
NASA Technical Reports Server (NTRS)
Bartlett, K. B.; Harriss, R. C.; Sebacher, D. I.
It is thought that biological methanogenesis in natural and agricultural wetlands and enteric fermentation in animals are the dominant sources of global tropospheric methane. It is pointed out that the anaerobic soils and sediments, where methanogenesis occurs, predominate in coastal marine wetlands. Coastal marine wetlands are generally believed to be approximately equal in area to freshwater wetlands. For this reason, coastal marine wetlands may be a globally significant source of atmospheric methane. The present investigation is concerned with the results of a study of direct measurements of methane fluxes to the atmosphere from salt marsh soils and of indirect determinations of fluxes from tidal creek waters. In addition, measurements of methane distributions in coastal marine wetland sediments and water are presented. The results of the investigation suggest that marine wetlands provide only a minor contribution to atmospheric methane on a global scale.
Tidal salt marshes of the southeast Atlantic Coast: A community profile
Wiegert, R.G.; Freeman, B.J.
This report is part of a series of community profiles on the ecology of wetland and marine communities. This particular profile considers tidal marshes of the southeastern Atlantic coast, from North Carolina south to northern Florida. Alone among the earth's ecosystems, coastal communities are subjected to a bidirectional flooding sometimes occurring twice each day; this flooding affects successional development, species composition, stability, and productivity. In the tidally influenced salt marsh, salinity ranges from less than 1 ppt to that of seawater. Dominant plant species include cordgrasses (Spartina alterniflora and S. cynosuroides), black needlerush (Juncus romerianus), and salt marsh bulrush (Scirpus robustus). Both terrestrail and aquatic animals occur in salt marshes and include herons, egrets ospreys (Pandion haliaetus), bald eagles (Haliaeetus leucocephalus), alligators (Alligator Mississippiensis), manatees (Trichecus manatus), oysters, mussels, and fiddler crabs. Currently, the only significant direct commercial use of the tidal salt marshes is by crabbers seeking the blue crab Callinectes sapidus, but the marshes are quite important recreationally, aesthetically, and educationally. 151 refs., 45 figs., 6 tabs.
Tropical salt marsh succession as sea-level indicator during Heinrich events
NASA Astrophysics Data System (ADS)
Gonzßlez, Catalina; Dupont, Lydie M.
Centennial-millennial dynamics of tropical salt marsh vegetation are documented in the pollen record from marine core MD03-2622, Cariaco Basin, Venezuela, which spans the glacial period between 63 and 29 ka. Five rapid and abrupt expansions of salt marsh vegetation are linked with North Atlantic Heinrich events (HEs). Within each event, a recurrent pattern - starting with species of Chenopodiaceae, followed by grasses, and subsequently by Cyperaceae species - suggests a successional process that is determined by the close relationship between sea-level and community dynamics. The salt tolerant Chenopodiaceae, at the base of each sequence, indicate hypersaline intertidal environments, which were most likely promoted by extremely dry atmospheric conditions. Rapid sea-level rise characterizes the onset of HE stadials, causing erosion of marsh sediments, and continued recruitment of pioneer species (Chenopodiaceae), which are the only ones capable of tolerating the rapid rate of disturbance. Once, as sea-level drops or as rise decelerates, marsh plants are able to trap and stabilize sediments, favouring the establishment of more competitive species (graminoids). The increment of marsh height as a result of autochthonous sediment accumulation reduces the extent of hypersaline environments, and allows the establishment of mesohaline species. These results add to the scarce knowledge on tropical salt marsh ecosystems, and provide independent paleoclimatic evidence on sea-level changes occurring simultaneously with Antarctica climate variations.
We quantified nekton and estimated trophic export at salt marshes with both erosional and depositional edges at the Goodwin Islands (York River, Virginia, USA). At depositional-edge marshes, we examined trophic flows through quantitative sampling with 1.75 m2 drop rings, and thro...
Salt marsh Claviceps purpurea in native and invaded Spartina marshes in Northern California
Technology Transfer Automated Retrieval System (TEKTRAN)
The fungal pathogen Claviceps purpurea (subgroup G3) has a worldwide distribution on salt marsh Spartina species. In Northern California (US), native S. foliosa sustains high rates of infection by G3 C. purpurea in marshes north of the San Francisco Estuary. Invasive populations of S. alterniflora a...
Winter climate change and coastal wetland foundation species: salt marshes vs. mangrove forests in the southeastern United States
Osland, Michael J.; Day, Richard H.; Doyle, Thomas W.; Enwright, Nicholas
We live in an era of unprecedented ecological change in which ecologists and natural resource managers are increasingly challenged to anticipate and prepare for the ecological effects of future global change. In this study, we investigated the potential effect of winter climate change upon salt marsh and mangrove forest foundation species in the southeastern United States. Our research addresses the following three questions: (1) What is the relationship between winter climate and the presence and abundance of mangrove forests relative to salt marshes; (2) How vulnerable are salt marshes to winter climate change-induced mangrove forest range expansion; and (3) What is the potential future distribution and relative abundance of mangrove forests under alternative winter climate change scenarios? We developed simple winter climate-based models to predict mangrove forest distribution and relative abundance using observed winter temperature data (1970¢2000) and mangrove forest and salt marsh habitat data. Our results identify winter climate thresholds for salt marsh¢mangrove forest interactions and highlight coastal areas in the southeastern United States (e.g., Texas, Louisiana, and parts of Florida) where relatively small changes in the intensity and frequency of extreme winter events could cause relatively dramatic landscape-scale ecosystem structural and functional change in the form of poleward mangrove forest migration and salt marsh displacement. The ecological implications of these marsh-to-mangrove forest conversions are poorly understood, but would likely include changes for associated fish and wildlife populations and for the supply of some ecosystem goods and services.
Winter climate change and coastal wetland foundation species: salt marshes vs. mangrove forests in the southeastern United States.
Osland, Michael J; Enwright, Nicholas; Day, Richard H; Doyle, Thomas W
We live in an era of unprecedented ecological change in which ecologists and natural resource managers are increasingly challenged to anticipate and prepare for the ecological effects of future global change. In this study, we investigated the potential effect of winter climate change upon salt marsh and mangrove forest foundation species in the southeastern United States. Our research addresses the following three questions: (1) What is the relationship between winter climate and the presence and abundance of mangrove forests relative to salt marshes; (2) How vulnerable are salt marshes to winter climate change-induced mangrove forest range expansion; and (3) What is the potential future distribution and relative abundance of mangrove forests under alternative winter climate change scenarios? We developed simple winter climate-based models to predict mangrove forest distribution and relative abundance using observed winter temperature data (1970-2000) and mangrove forest and salt marsh habitat data. Our results identify winter climate thresholds for salt marsh-mangrove forest interactions and highlight coastal areas in the southeastern United States (e.g., Texas, Louisiana, and parts of Florida) where relatively small changes in the intensity and frequency of extreme winter events could cause relatively dramatic landscape-scale ecosystem structural and functional change in the form of poleward mangrove forest migration and salt marsh displacement. The ecological implications of these marsh-to-mangrove forest conversions are poorly understood, but would likely include changes for associated fish and wildlife populations and for the supply of some ecosystem goods and services. PMID:23504931
Hydrodynamic forcing on salt-marsh development: Distinguishing the relative importance of waves and tidal flows
NASA Astrophysics Data System (ADS)
Callaghan, D. P.; Bouma, T. J.; Klaassen, P.; van der Wal, D.; Stive, M. J. F.; Herman, P. M. J.
To unravel the relation between hydrodynamic forcing and the dynamics of the tidal flat-salt-marsh ecosystem, we compared hydrodynamic forcing in terms of proxies relevant to bed sediment motion for four tidal flat-salt-marsh ecosystems that were contrasting in terms of wind exposure (sheltered vs. exposed) and lateral development (shrinking vs. expanding). Wave and current field measurements on these four contrasting tidal flat and salt-marsh ecosystems indicated that the hydrodynamic forcing on the bottom sediment (bed shear stress) was strongly influenced by wind-generated waves, more so than by tidal- or wind-drive currents. The measurements further showed that the hydrodynamic forcing decreased considerably landward of the marsh cliff, highlighting a transition from vigorous (tidal flat and pioneer zone) to sluggish (mature marsh) fluid forcing. Spatial wave modeling using measured wind, revealed that the time-integrated wave forcing on the intertidal mudflat in front of the marsh (i.e., the potential bed sediment pickup) was a factor two higher for salt marshes that are laterally shrinking than for laterally expanding marshes, regardless of whether these marshes were exposed to or sheltered from the wind. The same result could not be obtained from a straightforward wind speed and fetch length approach for estimating wave forcing. This confirmed that wave force estimates required spatial modeling to be consistent with the sites trends of shrinking or expanding marshes and wind exposure is not enough to characterize the wave forcing at these sites. Seasonal changes in wave forcing identified from wind measurements potentially provide an alternative mechanism for marsh cliff formation. During the calm summer, fine sediments switches from the water column to the bed. During the following winter, fine sediment is retained within the vegetated regions while being returned to the water column from the bare tidal flats. The continuous slow upward growth of vegetated areas combined with the seasonal cyclic tidal flat elevations, could, during winter, cause a discontinuity at the bare/vegetated boundary. If this discontinuity grows large enough for plant die-off to occur, then a small cliff will form.
The Global Carbon Sink in Tidal Salt Marshes
NASA Astrophysics Data System (ADS)
Chmura, G. L.
For decades researchers have concentrated on proving that C is exported from salt marshes to coastal waters, with limited success. Yet, the C retained in the marsh soils may be equally important. Presumptions that minor amounts of C are stored in salt marsh soils are based upon measurements of low percentages of C in many marshes. Simply measuring the organic matter content of marsh soils provides little indication of the amount or rate of C stored, as this parameter is based upon the percent by mass of the soil. The critical parameter to calculate is C density, derived from percent organic matter and bulk density. (The latter is often neglected in marsh soil studies.) Calculation of C density reveals that minerogenic soils with high bulk densities may have C densities or C storage rates equivalent to more organic soils with low bulk densities. A global average soil C density of 0.055 ▒ 0.004 g cm-3 has been calculated from 107 measurements reported for salt marshes around the world (Gulf of Mexico, NE and NW Atlantic, Mediterranean and NE Pacific). Assuming an average marsh soil depth of 0.5 m and using inventories of marsh area available for Europe, Scandinavia, Africa, Canada and the U.S., the C stored globally in salt marshes is greater than 430 ▒ 30 Tg C. The global carbon storage could be twice this as there are no marsh inventories available for Asia or South America. Rates of C storage can be calculated from 96 C density measurements where soil accretion rates also were measured. Globally, marshes sequester an average of 210 g CO2 m-2 yr-1, an order of magnitude greater than rates reported for peatlands. Salt marsh C storage can have regional importance. At a magnitude of 5 Tg C yr-1, tidal wetlands comprise 1--2 percent of the C sink (300--580 Tg C yr-1) estimated for the coterminous U.S. In the Bay of Fundy restoration of salt marshes reclaimed for agricultural land could enable sequestration of an additional 240 to 360 Gg C yr-1, equivalent to 4 to 6 percent of Canada's targeted reduction of 1990-level emissions of CO2 under the Kyoto Protocol. The C sink in salt marsh soils has advantages over those in freshwater wetlands or terrestrial soils. Presence of abundant sulfate limits release of the potent greenhouse gas, methane, which can be released in substantial quantities from freshwater wetland soils. In salt marshes, turnover of C occurs on time scales of hundreds to thousands of years, whereas the C content of terrestrial soils reaches equilibrium in decades to 100 yr. In many marshes C sequestration will continue or perhaps increase with higher rates of sea level rise accompanying global warming, as soil accretion rates will be greater. However, human impacts on many salt marshes (altering hydrological regimes or displacing sediment supplies), such as those of the Mississippi Delta, limits their sustainability in the face of higher rates of sea level rise and the future of these C sinks is threatened. Future research on C storage in salt marshes must be directed at local controls, for there is as much variability in a single region (e.g., Long Island Sound or the Bay of Fundy) as there is globally. Intensive sampling at multiple elevations in a single marsh reveals C densities to be significantly greater at higher elevations, but rates of C accumulation decline with elevation. Controlling for this variability in elevation reveals that C density decreases with average annual temperature, thus greater understanding of local processes are critical to detect global patterns.
Transport of particulate organic material between salt marsh and estuary
W. J. Wolff
The macrophyte production and the transport of particulate organic matter between march and adjacent estuary have been investigated for a 30 ha salt marsh along the Oosterschelde estuary, The Netherlands.
Production ecology in southern California coastal salt marshes was investigated by harvesting macrophytes and monitoring environmental factors (substrate salinity, pH, nitrogen, redox, water content, temperature, and tide level) at four locations--Sweetwater River Estuary, Los Pe...
Wave attenuation over coastal salt marshes under storm surge conditions
M÷ller, Iris; Kudella, Matthias; Rupprecht, Franziska; Spencer, Tom; Paul, Maike; van Wesenbeeck, Bregje K.; Wolters, Guido; Jensen, Kai; Bouma, Tjeerd J.; Miranda-Lange, Martin; Schimmels, Stefan
Coastal communities around the world face increasing risk from flooding as a result of rising sea level, increasing storminess, and land subsidence1¢2. Salt marshes can act as natural buffer zones, providing protection from waves during storms3...
Degradation and resilience in Louisiana salt marshes after the BP-Deepwater Horizon oil spill.
Silliman, Brian R; van de Koppel, Johan; McCoy, Michael W; Diller, Jessica; Kasozi, Gabriel N; Earl, Kamala; Adams, Peter N; Zimmerman, Andrew R
More than 2 y have passed since the BP-Deepwater Horizon oil spill in the Gulf of Mexico, yet we still have little understanding of its ecological impacts. Examining effects of this oil spill will generate much-needed insight into how shoreline habitats and the valuable ecological services they provide (e.g., shoreline protection) are affected by and recover from large-scale disturbance. Here we report on not only rapid salt-marsh recovery (high resilience) but also permanent marsh area loss after the BP-Deepwater Horizon oil spill. Field observations, experimental manipulations, and wave-propagation modeling reveal that (i) oil coverage was primarily concentrated on the seaward edge of marshes; (ii) there were thresholds of oil coverage that were associated with severity of salt-marsh damage, with heavy oiling leading to plant mortality; (iii) oil-driven plant death on the edges of these marshes more than doubled rates of shoreline erosion, further driving marsh platform loss that is likely to be permanent; and (iv) after 18 mo, marsh grasses have largely recovered into previously oiled, noneroded areas, and the elevated shoreline retreat rates observed at oiled sites have decreased to levels at reference marsh sites. This paper highlights that heavy oil coverage on the shorelines of Louisiana marshes, already experiencing elevated retreat because of intense human activities, induced a geomorphic feedback that amplified this erosion and thereby set limits to the recovery of otherwise resilient vegetation. It thus warns of the enhanced vulnerability of already degraded marshes to heavy oil coverage and provides a clear example of how multiple human-induced stressors can interact to hasten ecosystem decline. PMID:22733752
Degradation and resilience in Louisiana salt marshes after the BP¢Deepwater Horizon oil spill
Silliman, Brian R.; van de Koppel, Johan; McCoy, Michael W.; Diller, Jessica; Kasozi, Gabriel N.; Earl, Kamala; Adams, Peter N.; Zimmerman, Andrew R.
More than 2 y have passed since the BP¢Deepwater Horizon oil spill in the Gulf of Mexico, yet we still have little understanding of its ecological impacts. Examining effects of this oil spill will generate much-needed insight into how shoreline habitats and the valuable ecological services they provide (e.g., shoreline protection) are affected by and recover from large-scale disturbance. Here we report on not only rapid salt-marsh recovery (high resilience) but also permanent marsh area loss after the BP¢Deepwater Horizon oil spill. Field observations, experimental manipulations, and wave-propagation modeling reveal that (i) oil coverage was primarily concentrated on the seaward edge of marshes; (ii) there were thresholds of oil coverage that were associated with severity of salt-marsh damage, with heavy oiling leading to plant mortality; (iii) oil-driven plant death on the edges of these marshes more than doubled rates of shoreline erosion, further driving marsh platform loss that is likely to be permanent; and (iv) after 18 mo, marsh grasses have largely recovered into previously oiled, noneroded areas, and the elevated shoreline retreat rates observed at oiled sites have decreased to levels at reference marsh sites. This paper highlights that heavy oil coverage on the shorelines of Louisiana marshes, already experiencing elevated retreat because of intense human activities, induced a geomorphic feedback that amplified this erosion and thereby set limits to the recovery of otherwise resilient vegetation. It thus warns of the enhanced vulnerability of already degraded marshes to heavy oil coverage and provides a clear example of how multiple human-induced stressors can interact to hasten ecosystem decline. PMID:22733752
One of the most pervasive human impacts to salt marshes around the world is the introduction of nonnative species. Plant introductions to salt marsh systems have
Levin, Lisa
of nonnative species. Plant introductions to salt marsh systems have resulted in significant changes ranging changes experienced by salt marshes is the in- troduction of nonnative plants. Wetlands gener- ally23 One of the most pervasive human impacts to salt marshes around the world is the introduction
Effect of dominant Spartina species on salt marsh detritus production in SW Atlantic estuaries
NASA Astrophysics Data System (ADS)
Montemayor, Diana I.; Addino, Mariana; Fanjul, Eugenia; Escapa, Mauricio; Alvarez, M. Fernanda; Botto, Florencia; Iribarne, Oscar O.
Two cordgrass species of the genus Spartina cohabit in SW Atlantic (southern Brazil 31║48' S to Argentinean Patagonia, 43║20' S) salt marshes. Some salt marshes are dominated by the dense-flowered cordgrass Spartina densiflora (which inhabits the upper intertidal level) and others by the smooth cordgrass Spartina alterniflora (which inhabits the lower intertidal level). We investigated how the different species dominance affects the detritus dynamics in the Bahia Blanca estuary (38║47' S, 62║20' W Argentina). Field measurements of annual detritus production using destructive methods show that both plants are similar. However, detritus of S. alterniflora shows higher decomposition rates than that of S. densiflora. This difference may be due to a larger N content, lower lignocellulose content and lower C/N ratio of S. alternifora when compared with S. densiflora. Moreover, field sampling shows that S. alterniflora has a larger amount of trapped litter that, according to the litterbag method, has higher decomposition rates. Therefore it is highly likely that S. alterniflora salt marshes contribute towards more profitable detritus for estuarine food webs than marshes dominated by S. densiflora. These results illustrate that the composition of the coastal plant community can determine the quality and profitability of the detritus that support estuarine food webs. They also illustrate that salt marshes belonging to a same biogeographic group and even coexisting in great proximity can have very different ecosystemic roles.
Comparative Geomorphology of Salt and Tidal Freshwater Marsh Environments
NASA Astrophysics Data System (ADS)
Pasternack, G. B.
Temperate estuaries include a spectrum of coastal marshes ranging from highly saline near the ocean to fresh in tributaries with substantial watershed drainage. While the hydrologic, sedimentary, and geomorphic dynamics of salt marshes have been thoroughly investigated, those aspects of tidal freshwater marshes have only begun to be addressed. Based on a recent burst in research on tidal freshwater systems in Chesapeake Bay by different universities, an attempt is made here to provide comparative geomorphology. In terms of similarities, both have tidal channels whose hydraulic geometry is primarily controlled by the tidal prism. Both show decreasing sedimentation and increasing organics with elevation and distance from channels. At seasonal to interannual time scales, the morphodynamics of both show similarities in the interplay among hydroperiod, vegetation, and geomorphology. Rather than simply evolving from youth to maturity, both systems exhibit strong evidence for dynamic equilibrium between process and morphology. Despite these similarities, there are key differences that motivate further research of tidal freshwater marshes. First, whereas salt marshes are limited by sediment supply, tidal fresh ones may not be limited depending on upstream basin size. E.g., fringing marshes along Pumunkey River have very low sediment supply, while deltaic marshes in Bush River and Sassafras River are not supply-limited. Instead, the growth of deltaic fresh marshes is transport limited, as winds and tides can only generate low momentum and turbulence for sediment transport. As illustrated in multiple systems, a constant availability of sediment leads to higher sedimentation in fresh marshes. Second, in high latitude salt marshes where the tidal range is large and the climate cold, ice acts as a strong erosional agent. In fresh marshes, ice serves to sequester sediment and buffer the erosional impact of autumnal vegetation dieback. Third, the high spatial variation in plant associations in fresh marshes allows for a finer control of spatial patterns in sedimentation and erosion than is possible in salt marshes. Finally, the landscape position of fresh marshes places them near riparian forests that can supply large amounts of organics thereby promoting accretion.
Inventory and protection of salt marshes from risks of sea-level rise at Acadia National Park, Maine
Dudley, Robert W.; Nielsen, Martha G.
Recent U.S. Geological Survey (USGS) climate studies in the northeastern United States have shown substantial evidence of climate-related changes during the last 100 years, including earlier snowmelt runoff, decreasing occurrence of river ice, and decreasing winter snowpack. These studies related to climate change are being expanded to include investigation of coastal wetlands that might be at risk from sealevel rise. Coastal wetlands, particularly salt marshes, are important ecosystems that provide wildlife nursery and breeding habitat, migratory bird habitat, water quality enhancement, and shoreline erosion control. The USGS is investigating salt marshes in Acadia National Park with the goal of determining which salt marshes may be threatened by sea-level rise and which salt marshes may be able to adapt to sea-level rise by migrating into adjacent low-lying lands.
Salt stress limitation of seedling recruitment in a salt marsh plant community
Scott W. Shumway; Mark D. Bertness
Seedling recruitment in salt marsh plant communities is generally precluded in dense vegetation by competition from adults, but is also relatively rare in disturbance-generated bare space. We examined the constraints on seedling recruitment in New England salt marsh bare patches. Under typical bare patch conditions seed germination is severely limited by high substrate salinities. We examined the germination requirements of
Microbial community analysis of an Alabama coastal salt marsh impacted by the Deepwater Horizon Oil Spill
NASA Astrophysics Data System (ADS)
Beazley, M. J.; Martinez, R.; Rajan, S.; Powell, J.; Piceno, Y.; Tom, L.; Andersen, G. L.; Hazen, T. C.; Van Nostrand, J. D.; Zhou, J.; Mortazavi, B.; Sobecky, P. A.
Microbial community responses of an Alabama coastal salt marsh environment to the Deepwater Horizon oil spill were studied by 16S rRNA (PhyloChip) and functional gene (GeoChip) microarray-based analysis. Oil and tar balls associated with the oil spill arrived along the Alabama coast in June 2010. Marsh and inlet sediment samples collected in June, July, and September 2010 from a salt marsh ecosystem at Point Aux Pines Alabama were analyzed to determine if bacterial community structure changed as a result of oil perturbation. Sediment total petroleum hydrocarbon (TPH) concentrations ranged from below detection to 189 mg kg-1 and were randomly dispersed throughout the salt marsh sediments. Total DNA extracted from sediment and particulates were used for PhyloChip and GeoChip hybridization. A total of 4000 to 8000 operational taxonomic units (OTUs) were detected in marsh and inlet samples. Distinctive changes in the number of detectable OTUs were observed between June, July, and September 2010. Surficial inlet sediments demonstrated a significant increase in the total number of OTUs between June and September that correlated with TPH concentrations. The most significant increases in bacterial abundance were observed in the phyla Actinobacteria, Firmicutes, Gemmatimonadetes, Proteobacteria, and Verrucomicrobia. Bacterial richness in marsh sediments also correlated with TPH concentrations with significant changes primarily in Acidobacteria, Actinobacteria, Firmicutes, Fusobacteria, Nitrospirae, and Proteobacteria. GeoChip microarray analysis detected 5000 to 8300 functional genes in marsh and inlet samples. Surficial inlet sediments demonstrated distinctive increases in the number of detectable genes and gene signal intensities in July samples compared to June. Signal intensities increased (> 1.5-fold) in genes associated with petroleum degradation. Genes related to metal resistance, stress, and carbon cycling also demonstrated increases in oiled sediments. This study demonstrates the value of applying phylogenetic and functional gene microarray technology to characterize the extensive microbial diversity of marsh environments. Moreover, this technology provides significant insight into bacterial community responses to anthropogenic oil events.
Herbivory Drives the Spread of Salt Marsh Die-Off
Bertness, Mark D.; Brisson, Caitlin P.; Bevil, Matthew C.; Crotty, Sinead M.
Salt marsh die-off is a Western Atlantic conservation problem that has recently spread into Narragansett Bay, Rhode Island, USA. It has been hypothesized to be driven by: 1) eutrophication decreasing plant investment into belowground biomass causing plant collapse, 2) boat wakes eroding creek banks, 3) pollution or disease affecting plant health, 4) substrate hardness controlling herbivorous crab distributions and 5) trophic dysfunction releasing herbivorous crabs from predator control. To distinguish between these hypotheses we quantified these variables at 14 Narragansett Bay salt marshes where die-off intensity ranged from <5% to nearly 98%. Nitrogen availability, wave intensity and plant growth did not explain any variation in die-off. Herbivory explained 73% of inter-site variation in die-off and predator control of herbivores and substrate hardness also varied significantly with die-off. This suggests that salt marsh die-off is being largely driven by intense herbivory via the release of herbivorous crabs from predator control. Our results and those from other marsh systems suggest that consumer control may not simply be a factor to consider in marsh conservation, but with widespread predator depletion impacting near shore habitats globally, trophic dysfunction and runaway consumption may be the largest and most urgent management challenge for salt marsh conservation. PMID:24651837
Salt Marsh Harvest Mouse (Reithrodontomys Raviventris)
San Francisco Bay Ś which has already lost the majority of its marsh habitat since the 19th Century Ś could lose even more marshes by the year 2100 due to sea level rise, according to a new USGS report. Animations, graphs and data from the USGS Open File ReportĀ2013-1081 andĀth...
Impact of sheep grazing on juvenile sea bass, Dicentrarchus labrax L., in tidal salt marshes
Paris-Sud XI, Universit├® de
Impact of sheep grazing on juvenile sea bass, Dicentrarchus labrax L., in tidal salt marshes P L., from sheep grazed and ungrazed tidal salt marshes were com- pared qualitatively. Juvenile sea bass colonise the salt marsh at ¯ood during 43% of the spring tides which inundate the salt
Making and Measuring a Model of a Salt Marsh
ERIC Educational Resources Information Center
Fogleman, Tara; Curran, Mary Carla
Students are often confused by the difference between the terms "accuracy" and "precision." In the following activities, students explore the definitions of accuracy and precision while learning about salt march ecology and the methods used by scientists to assess salt marsh health. The activities also address the concept that the ocean supports aģ
Salt marsh vegetation change in response to tidal restriction
Charles T. Roman; William A. Niering; R. Scott Warren
Vegetation change in response to restriction of the normal tidal prism of six Connecticut salt marshes is documented. Tidal flow at the study sites was restricted with tide gates and associated causeways and dikes for purposes of flood protection, mosquito control, and\\/or salt hay farming. One study site has been under a regime of reduced tidal flow since colonial times,
Competitive displacement of a detritivorous salt marsh snail
Sarah C. Lee; Brian Reed Silliman
Here we examine the role of competitive interactions in controlling distributions of the most abundant omnivore¢detritivore snails in East Coast U.S. salt marshes (Melampus bidentatus and Littoraria irrorata). Both snails prefer to eat fungi growing on plant material, and the periwinkle Littoraria, a much larger snail, destroys marsh canopy when grazing fungal-infected plants, resulting in increased local desiccation stress. To
Salt marsh ecohydrological zonation due to heterogeneous vegetation - groundwater - surface water interactions
NASA Astrophysics Data System (ADS)
Moffett, K. B.; Gorelick, S.; McLaren, R.; Sudicky, E. A.
Among the most fundamental characteristics of intertidal salt marshes are distinctive vegetation zonation and tidally-forced hydrology. Vegetation zones often correlate with tidal hydrology and plant water use is significant in the wetland balance; however, specific links between vegetation zonation, plant water use, and spatiotemporally variable intertidal hydrology have eluded thorough characterization. This investigation developed the first comprehensive salt marsh ecohydrology models integrating the transient, 3D, coupled surface water and groundwater flow and plant water use of an intensively studied salt marsh field site. The physics-based modeling demonstrated that superimposing heterogeneous sediment hydraulic properties, evapotranspiration rates, and rooting depths, together with tidal dynamics, induced surprising spatial variations in root zone hydraulics: variations pronounced enough to constitute wholly different root zone habitats with different pressure heads, saturations, and vertical groundwater velocities. These diverse habitats were apparent only when both hydraulic and vegetative influences were accounted for, leading to their definition as discrete "ecohydrological zones." We distinguished five different ecohydrological zones (EHZs) by distinct combinations of sediment hydraulic properties and evapotranspiration rates and two EHZs by topography. The hydraulic variations among EHZs were masked shortly after a flooding tide, but again became prominent during prolonged marsh exposure. Boundaries between EHZs exhibited large gradients in head, saturation, and vertical flow magnitude and direction due to a combination of vegetation and sediment effects. We suggest that ecohydrological zones, combining spatially-variable topographic, sediment, and vegetation influences, are the fundamental spatial habitat units comprising the salt marsh ecosystem. This perspective contrasts with historical emphasis on vegetation zones as the foremost unit of habitat variation within salt marshes.
Understanding the primary productivity of salt marshes requires accurate estimates of biomass. Unfortunately, these estimates vary enough within and among salt marshes to require large numbers of replicates if the averages are to be statistically meaningful. Large numbers of repl...
The role of denitrification in the nitrogen cycle of New England salt marshes
Hamersley, Michael Robert
I used direct measurements of nitrogen gas (N? fluxes and a ╣?N stable isotope tracer to determine the contribution of denitrification to salt marsh sediment N cycling. Denitrification in salt marsh tidal creekbottoms is ...
Does vegetation prevent wave erosion of salt marsh edges?
Feagin, R. A.; Lozada-Bernard, S. M.; Ravens, T. M.; M÷ller, I.; Yeager, K. M.; Baird, A. H.
This study challenges the paradigm that salt marsh plants prevent lateral wave-induced erosion along wetland edges by binding soil with live roots and clarifies the role of vegetation in protecting the coast. In both laboratory flume studies and controlled field experiments, we show that common salt marsh plants do not significantly mitigate the total amount of erosion along a wetland edge. We found that the soil type is the primary variable that influences the lateral erosion rate and although plants do not directly reduce wetland edge erosion, they may do so indirectly via modification of soil parameters. We conclude that coastal vegetation is best-suited to modify and control sedimentary dynamics in response to gradual phenomena like sea-level rise or tidal forces, but is less well-suited to resist punctuated disturbances at the seaward margin of salt marshes, specifically breaking waves. PMID:19509340
Salt marsh response to the effects of physical and biological processes
NASA Astrophysics Data System (ADS)
Roner, Marcella; D'Alpaos, Andrea; Ghinassi, Massimiliano; Franceschinis, Erica; Realdon, Nicola; Marani, Marco
Salt marshes are widespread features of the tidal landscape governed by the interacting physical and biological processes. These crucially important ecosystems provide valuable services and are currently threatened by the effects of increasing rates of relative sea level rise (RSLR) and decreasing sediment supply. Although a few studies have analyzed the biomorphological evolution of salt marsh systems, a complete understanding of the two-way feedbacks between physical and biological processes is still lacking. The temporal evolution of marsh elevation is governed by the balance between inorganic and organic accretion rates, and the rate of RSLR. Studies based on field observations and modeling suggest that, in equilibrium conditions, marsh inorganic accretion rates, and the related platform elevations, decrease with distance from the main creek whereas the organic deposition gradually increases. In order to analyze salt marsh responses to the effect of physical and biological processes, about 100 sediment samples were collected on the San Felice salt marsh, Venice Lagoon. For each sample, local coordinates, surface elevations and vegetation cover were detected, whereas inorganic and organic sediment content, together with grain size distribution, were determined and analyzed. Loss On Ignition (LOI) and a double treatment with H2O2 and NaClO, were used to estimate the amount of organic matter in each sample. Particle size analysis was carried out on the inorganic fraction with a Mastersizer that uses laser diffraction techniques to measure the grain size. Our results show that the San Felice salt marsh is characterized by a concave-up profile, as commonly displayed by marshes worldwide. Marsh elevation is highest along the boundary and decreases toward the inner marsh. The inorganic deposition, which is maximum along the marsh edge, decreases with distance from the channel network, because as water moves across the marsh, the velocity is reduced and sediment particles are deposited. In contrast, the organic deposition, dictated by local plant productivity, gradually increases with distance from the channel to balance the decrease in the inorganic deposition and to help the marsh surface to keep pace with current rates of RSLR. Interestingly, we note that the amounts of organic and inorganic sediment display non-monotonically trends. Furthermore, regardless of the method used, the amounts of organic matter show the same qualitative trend, although characterized by different values for a single sample. The grain size of inorganic sediment show a variable distribution between medium sand and clay. In particular, the grains along marsh portions adjacent to the channels are coarser and become gradually finer toward the inner marsh, according to the transport capability of the tidal flow and the decrease in the water velocity away from the main channel. In particular, we observed that the location of the channels is an important factor controlling patterns of inorganic and organic deposition. Our results also suggest that halophytic vegetation species largely contribute to tune marsh elevation and bring new insight on the spatial distribution of organic and inorganic deposition rates.
Mangrove expansion and salt marsh decline at mangrove poleward limits.
Saintilan, Neil; Wilson, Nicholas C; Rogers, Kerrylee; Rajkaran, Anusha; Krauss, Ken W
Mangroves are species of halophytic intertidal trees and shrubs derived from tropical genera and are likely delimited in latitudinal range by varying sensitivity to cold. There is now sufficient evidence that mangrove species have proliferated at or near their poleward limits on at least five continents over the past half century, at the expense of salt marsh. Avicennia is the most cold-tolerant genus worldwide, and is the subject of most of the observed changes. Avicennia germinans has extended in range along the USA Atlantic coast and expanded into salt marsh as a consequence of lower frost frequency and intensity in the southern USA. The genus has also expanded into salt marsh at its southern limit in Peru, and on the Pacific coast of Mexico. Mangroves of several species have expanded in extent and replaced salt marsh where protected within mangrove reserves in Guangdong Province, China. In south-eastern Australia, the expansion of Avicennia marina into salt marshes is now well documented, and Rhizophora stylosa has extended its range southward, while showing strong population growth within estuaries along its southern limits in northern New South Wales. Avicennia marina has extended its range southwards in South Africa. The changes are consistent with the poleward extension of temperature thresholds coincident with sea-level rise, although the specific mechanism of range extension might be complicated by limitations on dispersal or other factors. The shift from salt marsh to mangrove dominance on subtropical and temperate shorelines has important implications for ecological structure, function, and global change adaptation. PMID:23907934
Spatial variability of phosphorus sorption dynamics in Louisiana salt marshes
NASA Astrophysics Data System (ADS)
Marton, John M.; Roberts, Brian J.
Phosphorus (P) biogeochemistry has been studied in multiple wetland ecosystems, though few data exist on P sorption in U.S. Gulf Coast marshes. There also is a limited understanding of how oil spills in coastal zones can influence P dynamics in wetland soils. In this study, we measured P sorption potential, using the P sorption index (PSI), soil properties, and P saturation at increasing distances from the marsh edge in oiled and unoiled marshes in three regions along the southeastern Louisiana coast (Terrebonne Bay, western, and eastern Barataria Bay). Individual PSI values were highly variable, ranging from 19.5 to 175.6 mg P 100 g-1 and varying by at least a factor of five within each of the three regions, and did not significantly differ between regions or between oiled and unoiled marshes. Soil pH, organic matter, total N, N:P ratio, moisture content, cation exchange capacity, and P saturation differed between regions, and all soil parameters showed great variability between and within individual marshes. Extractable iron was the strongest predictor of PSI across all regions, explaining between 51 and 95% of the variability in individual regions. PSI increased with distance from marsh edge in Terrebonne Bay where other soil properties exhibited similar trends. Results suggest mineral composition of marsh soils, influenced by elevation-inundation gradients, are critical in dictating P loading to estuaries and open waters, and overall marsh functioning. Further, within 2 years of the Deepwater Horizon oil spill, oiled marshes are able to sorb phosphorus at comparable levels as unoiled marshes.
Remote sensing of biomass of salt marsh vegetation in France
NASA Technical Reports Server (NTRS)
Gross, M. F.; Klemas, V.; Levasseur, J. E.
Spectral data (gathered using a hand-held radiometer) and harvest data were collected from four salt marsh vegetation types in Brittany, France, to develop equations predicting live aerial biomass from spectral measurements. Remote sensing estimates of biomass of the general salt marsh community (GSM) and of Spartina alterniflora can be obtained throughout the growing season if separate biomass prediction equations are formulated for different species mixtures (for the GSM) and for different canopy types (for S. alterniflora). Results suggest that remote sensing will not be useful for predicting Halimione portulacoides biomass, but can be used to estimate Puccinellia maritima biomass early in the growing season.
A watershed approach to examine measures of structure and function in salt marshes of similar geomorphology and hydrology in Narragansett Bay is being used to develop a reference system for evaluating salt marsh integrity. We describe integrity as the capability of a salt marsh t...
Distribution and salinity tolerance of intertidal mosses from Nova Scotian salt marshes
David J. Garbary; Anthony G. Miller; Ricardo Scrosati; Kwang-Young Kim; Wilfred B. Schofield
Five moss species were found in the high intertidal zone of salt marshes in Nova Scotia, eastern Canada. This is the first report of bryophytes from salt marshes from North America. In each of the salt marshes where mosses occurred, one to three moss species occurred in monospecific or mixed species assemblages. Campylium stellatum and Bryum capillare were the most
Abstract We explored the generality of the processes mediating shrub zonation in western Atlantic salt marsh-
Pennings, Steven C.
salt marsh- es by comparing the results of our experiments in Geor- gia, USA with previous studies from salt marshes. Within the shrub zone, physical stress increased at lower elevations, shrubs at lower gerardi in Rhode Island salt marshes. However, markedly different processes appear to occur further
Processes controlling the thermal regime of salt marsh channel beds Journal: Environmental Science & Technology
Selker, John
Processes controlling the thermal regime of salt marsh channel beds Journal: Environmental Science to Environmental Science & Technology #12;1 Processes controlling the thermal regime of salt marsh channel beds (DTS) system deployed along 330-m of two intertidal salt marsh channel2 beds in northern California
Microclimate and substrate quality controls on nitrogen mineralization in a New England high salt marsh
Theresa A. Theodose; Janette Martin
New England high salt marsh primary productivity is limited by N, but variation in plant N availability across salt marsh vegetation zones has not been quantified. To investigate this, we measured in situ net N mineralization rates throughout the growing season in three zones of a Maine high salt marsh, Juncus gerardii, Spartina patens, and mixed perennial forb. We also
Habitat selection of wintering passerines in salt marshes of the German Wadden Sea
Jochen Dierschke; Franz Bairlein
The salt marshes of the Wadden Sea are important wintering areas for some species of granivorous passerines, which have declined considerably since the 1960s. We investigated the habitat choice of all wintering passerines in eight study areas in German salt marshes with special consideration of human impact on these habitats. Granivorous species that almost exclusively winter in salt marshes, Shorelark
A watershed approach to examine measures of structure and function in salt marshes of similar geomorphology and hydrology in Narragansett Bay was used to develop a reference system for evaluating salt marsh integrity. We describe integrity as the capability of a salt marsh to pro...
A monitoring protocol to assess tidal restoration of salt marshes on local and regional scales
Neckles, H.A.; Dionne, M.D.; Burdick, D.M.; Roman, C.T.; Buchsbaum, R.; Hutchins, E.
Assessing the response of salt marshes to tidal restoration relies on comparisons of ecosystem attributes between restored and reference marshes. Although this approach provides an objective basis for judging project success, inferences can be constrained if the high variability of natural marshes masks differences in sampled attributes between restored and reference sites. Furthermore, such assessments are usually focused on a small number of restoration projects in a local area, limiting the ability to address questions regarding the effectiveness of restoration within a broad region. We developed a hierarchical approach to evaluate the performance of tidal restorations at local and regional scales throughout the Gulf of Maine. The cornerstone of the approach is a standard protocol for monitoring restored and reference salt marshes throughout the region. The monitoring protocol was developed by consensus among nearly 50 restoration scientists and practitioners. The protocol is based on a suite of core structural measures that can be applied to any tidal restoration project. The protocol also includes additional functional measures for application to specific projects. Consistent use of the standard protocol to monitor local projects will enable pooling information for regional assessments. Ultimately, it will be possible to establish a range of reference conditions characterizing natural tidal wetlands in the region and to compare performance curves between populations of restored and reference marshes for assessing regional restoration effectiveness.
Mechanistic models of nutrient dynamics in natural wetlands were developed and applied in a study of Kissimmee River (Florida) flood-plain marshes. The models describe hydrodynamics and transport diffusion in wetland basins and the ecological processes of nutrient uptake, convers...
Biogeomorphically driven salt pan formation in Sarcocornia-dominated salt-marshes
NASA Astrophysics Data System (ADS)
Escapa, Mauricio; Perillo, Gerardo M. E.; Iribarne, Oscar
Salt-marshes are under increasing threat, particularly from sea-level rise and increased wave action associated with climate change. The development and stability of these valuable habitats largely depend on complex interactions between biotic and abiotic processes operating at different scales. Also, interactions between biotic and abiotic processes drive internal morphological change in salt-marshes. In this paper we used a biogeomorphological approach to assess the impact of biological activities and interactions on salt pan formation in Sarcocornia-dominated salt marshes. Salt pans represent a key physiographic feature of salt-marshes and recent studies hypothesized that biogeomorphic processes could be related to salt pan formation in SW Atlantic salt-marshes. The glasswort Sarcocornia perennis is one of the dominant plants in the salt-marshes of the BahĒa Blanca Estuary (Argentina) where they form patches up to 8 m in diameter. These salt-marshes are also inhabited in great densities by the burrowing crab Neohelice (Chasmagnathus) granulata whose bioturbation rates are among the highest reported for salt-marshes worldwide. A set of biological interactions between N. granulata and S. perennis appears to be responsible for salt pan development in these areas which has not been described elsewhere. The main objective of this work was to determine the ecological interactions occurring between plants and crabs that lead to salt pan formation by using field-based sampling and manipulative experiments. Our results showed that S. perennis facilitated crab colonization of the salt-marsh by buffering otherwise stressful physical conditions (e.g., temperature, desiccation). Crabs preferred to construct burrows underneath plants and, once they reach high densities (up to 40 burrows m- 2), the sediment reworking caused plant die-off in the central area of patches. At this state, the patches lose elevation and become depressed due to the continuous bioturbation by crabs. Thus, salt pans are generated in this case by a set of biogeomorphic processes that include pure ecological interactions such as plant facilitation of crab settlement and also indirect negative effects of crabs on plant survival. Furthermore, crab bioturbation affects sediment structure due to concentration of burrowing activity under plant canopies promoting elevation loss and leading, after a few years, to salt pan formation in a previously vegetated substrate.
On salt marshes retreat: Experiments and modeling toppling failures induced by wind waves
NASA Astrophysics Data System (ADS)
Bendoni, M.; Francalanci, S.; Cappietti, L.; Solari, L.
Salt marshes are delicate ecosystems which are disappearing in many areas of the world, mainly due to increasing rates of sea level rise, subsidence, and anthropic pressure. The lateral erosion of the edge of salt marshes is one of the most important processes in determining changes in morphology, and wind waves have a key role in this retreat. Lateral retreat occurs by means of several types of mass failure processes, typically cantilever, sliding, and toppling. In the literature, no mechanistic models for the description of toppling failure are available. In this study, we performed a set of experiments to quantify the pressure field and the hydrodynamic forcing induced by wind waves during toppling failures of unstable blocks on a salt marsh edge. We propose a model interpreting toppling failure based on the experimental evidence as well as on the physics of the system. We model the system as a dynamic rigid block of cohesive soil, identified by the presence of a tension crack, subjected to hydrodynamic forces caused by impact of waves and resistive forces due to the block's weight and soil cohesion. The failure of the blocks occurs when the soil tensile strength is exceeded along the failure surface located at the base of the block. The model is able to reproduce failure processes observed in the laboratory. Moreover, the model reveals that the most critical conditions for marsh bank instability due to toppling failure are associated to the presence of water inside the tension crack and low water levels in front of the bank.
Accumulation, distribution and cellular partitioning of mercury in several halophytes of a contaminated salt marsh.
Castro, Rita; Pereira, Sofia; Lima, Ana; Corticeiro, Sofia; Vßlega, M¾nica; Pereira, Eduarda; Duarte, Armando; Figueira, Etelvina
This work evaluates the role of a plant community in mercury (Hg) stabilization and mobility in a contaminated Portuguese salt marsh. With this aim, the distribution of Hg in below and aboveground tissues, as well as the metal partitioning between cellular fractions (soluble and insoluble) in four different species (Triglochin maritima L., Juncus maritimus Lam, Sarcocornia perennis (Miller) A.J. Scott, and Halimione portulacoides (L.) Aellen) was assessed. Mercury accumulation, translocation and compartmentation between organs and cellular fractions were related to the plant species. Results showed that the degree of Hg absorption and retention was influenced both by environmental parameters and metal translocation/partitioning strategies. Different plant species presented different allocation patterns, with marked differences between monocots (T. maritima and J. maritimus) and dicots (S. perennis, H. portulacoides). Overall, the two monocots, in particular T. maritima showed higher Hg retention in the belowground organs whereas the dicots, particularly S. perennis presented a more pronounced translocation to the aboveground tissues. Considering cellular Hg partitioning, all species showed a higher Hg binding to cell walls and membranes rather than in the soluble fractions. This strategy can be related to the high degree of tolerance observed in the studied species. These results indicate that the composition of salt marsh plant communities can be very important in dictating the Hg mobility within the marsh ecosystem and in the rest of the aquatic system as well as providing important insights to future phytoremediation approaches in Hg contaminated salt marshes. PMID:19595432
Numerous bacteria from a salt-marsh environment are capable of degrading malathion, an organophosphate insecticide, when supplied with additional nutrients as energy and carbon sources. Seven isolates exhibited ability (48-90%) to degrade malathion as a sole carbon source. Gas an...
Results of Total Mercury Analysis in Salt Marsh Invertebrates
Analysis of blood samples obtained from saltmarsh sparrows revealed high levels (> 1.0 Ąg/g(wet)) of mercury (Hg) in sparrows inhabiting a salt marsh site in the Narrow River, RI (also known as Pettaquamscutt River). These analyses were conducted by Oksana Lane at the Biodiversit...
Latitudinal variation in herbivore pressure in Atlantic Coast salt marshes
Steven C. Pennings; Chuan-Kai Ho; Cristiano S. Salgado; Kazimierz Wi?ski; Nilam Davķ; Amy E. Kunza; Elizabeth L. Wason
Despite long-standing interest in latitudinal variation in ecological patterns and processes, there is to date weak and conflicting evidence that herbivore pressure varies with latitude. We used three approaches to examine latitudinal variation in herbivore pressure in Atlantic Coast salt marshes, focusing on five abundant plant taxa: the grass Spartina alterniflora, the congeneric rushes Juncus gerardii and J. roemerianus, the
Population biology of salt marsh and sand dune annuals
A. R. Watkinson; A. J. Davy
Annuals represent a significant component of the vegetation of coastal salt marshes and sand dunes. From many points of view, the two habitats might appear to have little in common. Yet both are characterized by episodes of low water potential, marked spatial and temporal heterogeneity and a zonation which, within certain limits, reflects successional change.
Effects of open marsh water management on numbers of larval salt marsh mosquitoes
James-Pirri, Mary-Jane; Ginsberg, Howard S.; Erwin, R. Michael; Taylor, Janith
Open marsh water management (OMWM) is a commonly used approach to manage salt marsh mosquitoes than can obviate the need for pesticide application and at the same time, partially restore natural functions of grid-ditched marshes. OMWM includes a variety of hydrologic manipulations, often tailored to the specific conditions on individual marshes, so the overall effectiveness of this approach is difficult to assess. Here, we report the results of controlled field trials to assess the effects of two approaches to OMWM on larval mosquito production at National Wildlife Refuges (NWR). A traditional OMWM approach, using pond construction and radial ditches was used at Edwin B. Forsythe NWR in New Jersey, and a ditch-plugging approach was used at Parker River NWR in Massachusetts. Mosquito larvae were sampled from randomly placed stations on paired treatment and control marshes at each refuge. The proportion of sampling stations that were wet declined after OMWM at the Forsythe site, but not at the Parker River site. The proportion of samples with larvae present and mean larval densities, declined significantly at the treatment sites on both refuges relative to the control marshes. Percentage of control for the 2 yr posttreatment, compared with the 2 yr pretreatment, was >90% at both treatment sites.
Effects of open marsh water management on numbers of larval salt marsh mosquitoes.
James-Pirri, Mary-Jane; Ginsberg, Howard S; Erwin, R Michael; Taylor, Janith
Open marsh water management (OMWM) is a commonly used approach to manage salt marsh mosquitoes than can obviate the need for pesticide application and at the same time, partially restore natural functions of grid-ditched marshes. OMWM includes a variety of hydrologic manipulations, often tailored to the specific conditions on individual marshes, so the overall effectiveness of this approach is difficult to assess. Here, we report the results of controlled field trials to assess the effects of two approaches to OMWM on larval mosquito production at National Wildlife Refuges (NWR). A traditional OMWM approach, using pond construction and radial ditches was used at Edwin B. Forsythe NWR in New Jersey, and a ditch-plugging approach was used at Parker River NWR in Massachusetts. Mosquito larvae were sampled from randomly placed stations on paired treatment and control marshes at each refuge. The proportion of sampling stations that were wet declined after OMWM at the Forsythe site, but not at the Parker River site. The proportion of samples with larvae present and mean larval densities, declined significantly at the treatment sites on both refuges relative to the control marshes. Percentage of control for the 2 yr posttreatment, compared with the 2 yr pretreatment, was >90% at both treatment sites. PMID:19960686
Feedbacks Between Flow, Sedimentation, and Standing Biomass on Salt-Marsh Platforms
NASA Astrophysics Data System (ADS)
Mudd, S. M.; Furbish, D. J.
Tidally induced flood-and-ebb flows over salt-marsh platforms are modeled using a nonlinear diffusion-like equation obtained from depth-integration of continuity and momentum equations for low Reynolds number flows. The diffusivity coefficient varies locally as a function of the standing biomass on the platform due to the drag of plant stems. Sedimentation on the platform is due to particle settling and trapping by plants, and thus feedbacks exist between flow, suspended-sediment transport, sedimentation, and the standing biomass of the macrophytes (i.e. Spartina alterniflora) living on the marsh. Standing biomass is a function of the time-averaged water depth above the platform, which varies spatially, and the time of year due to seasonal growing cycles. Plant stem density is a function of standing biomass, which can be calculated using measured self-thinning curves for crowded marsh ecosystems. The stem density, in turn, affects the tidal flow through variations in drag as the flood and ebb waters make their way through the macrophyte communities. Simulations suggest that, on short timescales (annual to decadal) the elevation of the marsh surface is the dominant factor in determining average depth of flow on the salt marsh in comparison to flow impedance effects associated with variations in drag (and therefore the diffusivity) due to the plant stems. Therefore the spatial pattern of plant density on the platform surface is more sensitive to the platform elevation (including its slope) than to the details of how the flow dynamics vary with biomass. Small spatial variations in flow due to spatial variations in biomass do affect the residence time of water on the salt marsh, however, and at longer timescales the spatial variation in sedimentation due to these subtle flow effects becomes important.
Diversity, composition, and geographical distribution of microbial communities in California salt marsh sediments
Cordova-Kreylos, A. L.; Cao, Y.; Green, P.G.; Hwang, H.-M.; Kuivila, K.M.; LaMontagne, M.G.; Van De Werfhorst, L. C.; Holden, P.A.; Scow, K.M.
The Pacific Estuarine Ecosystem Indicators Research Consortium seeks to develop bioindicators of toxicant-induced stress and bioavailability for wetland biota. Within this framework, the effects of environmental and pollutant variables on microbial communities were studied at different spatial scales over a 2-year period. Six salt marshes along the California coastline were characterized using phospholipid fatty acid (PLFA) analysis and terminal restriction fragment length polymorphism (TRFLP) analysis. Additionally, 27 metals, six currently used pesticides, total polychlorinated biphenyls and polycyclic aromatic hydrocarbons, chlordanes, nonachlors, dichlorodiphenyldichloroethane, and dichlorodiphenyldichloroethylene were analyzed. Sampling was performed over large (between salt marshes), medium (stations within a marsh), and small (different channel depths) spatial scales. Regression and ordination analysis suggested that the spatial variation in microbial communities exceeded the variation attributable to pollutants. PLFA analysis and TRFLP canonical correspondence analysis (CCA) explained 74 and 43% of the variation, respectively, and both methods attributed 34% of the variation to tidal cycles, marsh, year, and latitude. After accounting for spatial variation using partial CCA, we found that metals had a greater effect on microbial community composition than organic pollutants had. Organic carbon and nitrogen contents were positively correlated with PLFA biomass, whereas total metal concentrations were positively correlated with biomass and diversity. Higher concentrations of heavy metals were negatively correlated with branched PLFAs and positively correlated with methyl- and cyclo-substituted PLFAs. The strong relationships observed between pollutant concentrations and some of the microbial indicators indicated the potential for using microbial community analyses in assessments of the ecosystem health of salt marshes. Copyright ?? 2006, American Society for Microbiology. All Rights Reserved.
Soil Respiration and Belowground Carbon Stores Among Salt Marshes Subjected to Increasing Watershed Nitrogen Loadings in Southern New England
Coastal salt marshes are ecosystems located between the uplands and sea, and because of their location are subject to increasing watershed nutrient loadings and rising sea levels. Residential development along the coast is intense, and there is a significant relationship between...
Links Between Watershed Activities and the Degradation of Coastal, Tidal Salt Marshes in Southern New England USA
Human activities (e.g., land development, wastewater) in coastal watersheds in New England USA are linked with community- and system-level changes in tidal, organic-rich salt marshes. Significant relationships between various indicators of watershed activities and ecosystem stru...
Vulnerability of Northeastern U.S. Salt Marshes to Climatic and Anthropogenic Stressors
In the Northeastern U.S., salt marsh area is in decline. Habitat change analysis has revealed fragmentation, displacement of high marsh by low marsh species, and marsh drowning, while development of adjacent uplands limits upslope migration. Using inundation experiments, field s...
Historical rates of salt marsh accretion on the outer Bay of Fundy
Gail L. Chmura; Laurie L. Helmer; C. Beth Beecher; Elsie M. Sunderland
We examine rates of salt marsh accumulation in three marshes of the outer Bay of Fundy. At each marsh we selected a site in the high marsh with similar vegetation, and thus similar elevation. Accretion rates were estimated by 137 Cs, 210Pb, and pollen stratigraphy to estimate rates of change over periods of 30, 100, and ?170 years, respectively. These
Tidal circulation alteration for salt marsh mosquito control
NASA Astrophysics Data System (ADS)
Resh, Vincent H.; Balling, Steven S.
Mosquito control ditches designed to increase tidal circulation are widely used as a physical control alternative to insecticidal applications The impact of such ditching on Pacific Coast marshlands was largely unknown before this five-year study of impact in two types of San Francisco Bay salt marshes, a Salicornia virginica (pickleweed) monoculure and a mixed vegetation marsh Results of our studies suggest that ditches cause less environmental disturbance than insecticidal applications The article describes the following environmental consequences of ditching for mosquito control: increased tidal flushing of soils occurs adjacent to ditches compared with that in the open marsh, thereby reducing ground water and soil surface salinities and water table height; primary productivity of S. virginica, as determined by both the harvest method and infrared photographic analysis, is higher directly adjacent to ditches than in the open marsh, distribution of selected arthropod populations is similar at ditches and natural channels, although arthropod community response differs seasonally; aquatic invertebrate biomass is similar within ditched and natural ponds, but diversity is lower in ditched habitats, ditching increases fish diversity and density by improving fish access from tidal channels; ditches provide additional salt marsh song sparrow habitat, although ditches are less preferred than natural channels or sloughs. Management criteria can be used to design ditches that provide effective mosquito control and reduced environmental impact
Hydrologic variability in a salt marsh: Assessing the links between drought and acute marsh dieback
NASA Astrophysics Data System (ADS)
Hughes, Andrea L. H.; Wilson, Alicia M.; Morris, James T.
It has been hypothesized that acute marsh dieback (AMD) observed along the Gulf Coast and South Atlantic Bight in the early 2000s was the result of drought-induced changes to porewater and sediment chemistry through hypersalinity or through mobilization of metals and acidification associated with redox changes. The impact of drought on coastal wetlands remains unclear because the hydrology of these wetlands is strongly influenced by regular tidal inundation. In order to test the links between hydrologic variability and changes to marsh groundwater conditions that may be stressful to the salt marsh grass Spartina alterniflora, we installed piezometers and passive diffusion samplers in a salt marsh island at North Inlet, South Carolina, where AMD was observed in fall 2001. Significant variations in tidal inundation, rainfall, evapotranspiration, groundwater dynamics, and porewater chemistry were observed. The island was typically inundated twice daily, but there were occasional 19-21Āh periods in winter and spring when the marsh was not inundated and a singular event when the marsh was not inundated for three days (March 2008). Enhanced exposure resulted in seasonal redox chemistry changes, as indicated by changes in the ratio of ferrous iron [Fe(II)] to total iron [Fe(II)Ā+ĀFe(III)], but our observations do not support redox and pH changes as the cause of AMD at this site. Porewater salinity varied from 14 to 40 in the upper 1Ām of the marsh. Salinity was most variable near the surface and increased with depth, reflecting root zone transpiration and downward movement of porewater through the marsh mud into the underlying confined sand aquifer. Pearson Correlation tests among porewater constituents and hydrologic parameters indicated significant associations between porewater salinity, tidal inundation, rainfall, and ET, and additional associations between porewater iron concentration, speciation, and tidal inundation. Linear regression model estimates of porewater salinity for 2001-2002 did not indicate the development of hypersalinity during that period. However, these estimates did predict a dramatic increase in salinity that coincided with the beginning of drought conditions just prior to the observation of AMD, suggesting this as a cause for AMD at this site. Drought is predicted to increase over the next century; damage caused by potential increases in the frequency of drought-related AMD may limit the ability of intertidal salt marshes to accommodate sea level rise.
Assessing the Wildlife Habitat Value of New England Salt Marshes: I. Model and Application
We developed an assessment model to quantify the wildlife habitat value of New England salt marshes based on marsh characteristics and the presence of habitat types that influence habitat use by terrestrial wildlife. Applying the model to12 salt marshes located in Narragansett B...
Marsh Collapse Does Not Require Sea Level Rise
Fagherazzi, Sergio
Salt marshes are among the most productive ecosystems on Earth, providing nurseries for fish species and shelter and food for endangered birds. Salt marshes also mitigate the impacts of hurricanes and tsunamis, and sequester ...
Algal productivity in salt marshes of Georgia
ABSTRACT Gross primary,production,of algae,in the intertidal,marshes,on the,coast,of Georgia,was measured at various seasons. Measurements were also made of light, temperature, pH, depth of flooding at high tide, and sedimentary chlorophyll. Migration of the algae in t,he sediments,was,observed,along,creek,borders. Production,during,low tide is 150 mg,C\\/m2\\/hr in winter,and 2&30 mg,C\\/mz\\/hr in summer. Production under water, during high tide is 200 mg C\\/m2\\/hr in August and
Modeling the Retreat Processes of Salt Marsh Edge
NASA Astrophysics Data System (ADS)
Bendoni, M.; Cappietti, L.; Francalanci, S.; Rinaldi, M.; Solari, L.
Edge erosion of salt marshes due to surface waves and tide forcing is likely the chief mechanism that models marsh boundaries and by which salt marshes in worldwide coastal areas are being lost. In order to address this problem, experimental observations in a laboratory flume and field measurements in the lagoon of Venice were conducted to understand the main processes controlling marsh edge retreat, with a focus on the erosion mechanisms caused by the action of wind and tidal waves. A physical model reproducing a salt marsh bank was built inside a long wave current flume where random surface waves were generated according to a given wave spectrum. The physical model was constructed with the original soil and plants taken in a marsh of the lagoon of Venice, while the wave climate was reproduced according to field measurements. The experiments were conducted in the case of both unvegetated and vegetated bank: a first set of experiments was carried out considering only tidal wave; in the second, bank models experienced the effect of wind waves superimposed to the tide. The following data were collected during the experiments: wave climate interacting with the bank, flow velocity measurements in the eroded quasi-equilibrium configuration, pressure distribution along bank edge and internal pressure fluctuation and damping due to wave impact. Bank geometry profile and bottom topography at different times have also been collected to characterize the erosion rate with time and the evolution of bank retreat. Subsequent to laboratory activity wave climate was measured close to a marsh edge in the Lagoon of Venice with the aim at identifying wave forcing on the bank surface during a moderate wind event and comparing results with the wave stress experienced by bank models in laboratory tests. Several pressure transducers installed close to the bed were used to collect wave height and wave direction with respect to the edge of the marsh. Laboratory data and field measurement were analyzed and interpreted in order to develop a simple preliminary model describing the retreat processes of a bank edge subjected to wave attack and tidal forcing. The model applies to cohesive banks determining their temporal evolution under specific boundary and initial conditions. It takes into account processes induced by hydrodynamic forcing such as particle by particle erosion and mass failure triggered by the presence of tension cracks, whereas long time scale processes such as deposition and compaction are not considered.
Oil bioremediation in salt marsh mesocosms as influenced by nitrogen, phosphorus, and bacterial seeding
Wright, Alan Lee
Glasshouse experiments were conducted to determine the effects of N and P fertilization and bacterial seeding on crude oil degradation in salt marsh mesocosms containing marsh soil and Spartina alterniflora. Fertilization with urea, NH4, and N03...
Flow, Sedimentation, and Biomass Production on a Vegetated Salt Marsh in South Carolina
9 Flow, Sedimentation, and Biomass Production on a Vegetated Salt Marsh in South Carolina: Toward studies at North Inlet estuary, South Carolina, the biomass of the S. alterniflora on the marsh platform
Salt Marsh Formation in the Lower Hudson River Estuary
NASA Technical Reports Server (NTRS)
Merley, Michael; Peteet, Dorothy; Hansen, James E. (Technical Monitor)
Salt marshes are constant depositional environments and as a result contain accurate indicators of past relative sea level rise and salinity. The Hudson River marshes are at least twice as deep when compared to coastal marshes on either side of the mouth of the Hudson. The reason for this difference in sedimentation is unclear. This study uses macrofossil data as well as sediment stratigraphy in order to understand the formation and evolution of these marshes. The composition of seeds, roots, shoots and foraminifera, are used to indicate past sea levels. The four sites involved in this study are, from south to north, the Arthur Kill Marsh in Staten Island (40 36 N, 74 77W), Piermont marsh (N 4100; 73 55W) Croton Point (41 14 N; 73 50W) and Iona Island (41 18N, 73 58W). These are all tidally influenced but with increasing distances from the New York Bight, which gives a good spectrum of tidal influence. AMS-C14 dates on basal macrofossils will document the time of each marsh formation. Basal material from Arthur Kill (8 m) includes freshwater seeds such as Viola, Potomageton and Alnus along with Salix buds. Basal material from Croton Point (10 m) includes fibrous woody material, foraminifera and Zanichellia seeds and other brackish vegetational components. The basal material from Piermont (13.77 m) is lacking any identifiable macrofossils between 150 and 500 microns. The basal material from Iona Island (10 m) has vegetation such as Scirpus and Cyperus seeds, probably implying a brackish environment. The freshwater origin of the Arthur Kill marsh in Staten Island is significant because it predates either sea level rise or the western channel incision. Additional implications for this study include evidence for changes in river channel geomorphology. Reasons for the relatively deeper river marshes include possible basal clay compaction, high production due to river and marine nutrients as well as tectonic activity. This study provides the groundwork for more high-resolution studies of these marshes to understand the fluctuations in salinity caused by relative sea level rise, tectonic faulting and/or changes in precipitation/evaporation.
Biogeochemical effects of seawater restoration to diked salt marshes
Portnoy, J.W.; Giblin, A.E.
We conducted greenhouse microcosm experiments to examine the biogeochemical effects of restoring seawater to historically diked Cape Cod salt marshes. Peat cores from both seasonally flooded and drained diked marshes were waterlogged with seawater, and porewater chemistry was subsequently monitored for 21 mo. The addition of seawater to highly organic, seasonally flooded peat caused the death of freshwater wetland plants, 6-8 cm of sediment subsidence, and increased N and P mineralization. Also, sulfides and alkalinity increased 10-fold, suggesting accelerated decomposition by sulfate reduction. Addition of seawater to the low-organic-content acidic peat from the drained marsh increased porewater pH, alkalinity, PO4-P, and Fe(II), which we attribute to the reestablishment of SO4 and Fe(III) mineral reduction. Increased cation exchange contributed to 6-fold increases in dissolved Fe(II) and Al and 60-fold increases in NH4-N within 6 mo of sail-nation. Seawater reintroductions to seasonally flooded diked marshes will cause porewater sulfides to increase, likely reducing the success of revegetation efforts. Sulfide toxicity is of less concern in resalinated drained peats because of the abundance of Fe(II) to precipitate sulfides, and of NH4-N to offset sulfide inhibition of N uptake. Restoration of either seasonally flooded or drained diked marshes could stimulate potentially large nutrient and Fe(II) releases, which could in turn increase primary production and lower oxygen in receiving waters. These findings suggest that tidal restoration be gradual and carefully monitored.
Identification of metrics to monitor salt marsh integrity on National Wildlife Refuges in relation to conservation and management objectives
Neckles, Hilary A.; Guntenspergen, Glenn R.; Shriver, W. George; Danz, Nicholas P.; Wiest, Whitney A.; Nagel, Jessica L.; Olker, Jennifer H.
Most salt marshes in the US have been degraded by human activities, and threats from physical alterations, surrounding land-use, species invasions, and global climate change persist. Salt marshes are unique and highly productive ecosystems with high intrinsic value to wildlife, and many National Wildlife Refuges (NWRs) have been established in coastal areas to protect large tracts of salt marsh and wetland-dependent species. Various management practices are employed routinely on coastal NWRs to restore and enhance marsh integrity and ensure ecosystem sustainability. Prioritizing NWR salt marshes for application of management actions and choosing among multiple management options requires scientifically-based methods for assessing marsh condition. Monitoring is integral to structured decision-making (SDM), a formal process for decomposing a decision into its essential elements. Within a natural resource context, SDM involves identifying management objectives, alternative management actions, and expected management outcomes. The core of SDM is a set of criteria for measuring system performance and evaluating management responses. Therefore, use of SDM to frame natural resource decisions leads to logical selection of monitoring attributes that are linked explicitly to management needs. We used SDM to guide selection of variables for monitoring the ecological integrity of salt marshes within the National Wildlife Refuge System (NWRS). Our objectives were to identify indicators of salt marsh integrity that are effective across large geographic regions, responsive to a wide range of threats, and feasible to implement within funding and staffing constraints of the NWRS. In April, 2008, we engaged interdisciplinary experts in a week-long rapid prototyping SDM workshop to define the essential elements of salt marsh management decisions on refuges throughout the northeastern, southwestern, and northwestern US, corresponding to respective Regions 5, 2, and 1 of the US Fish and Wildlife Service (FWS). Through this process we identified measurable attributes for monitoring salt marsh ecosystems that are integrated into conservation practice and target management objectives. The following salt marsh attributes were identified through the SDM process either for describing state condition to determine management needs or for evaluating the achievement of management objectives: historical condition and geomorphic setting; ditch density; surrounding land use; ratio of open water area to vegetation area; rate of pesticide application; environmental contaminant concentration; change in marsh surface elevation relative to sea level rise; tidal range and groundwater level; surface topography; salinity; and species composition and abundance of vegetation, invasive species, invertebrates, nekton, and breeding and wintering birds. The identified attributes were too broadly defined to serve as operational monitoring variables. Therefore, we tested specific metrics for quantifying most of these attributes in summers of 2008 and 2009. The first four attributes in the above list can be characterized by office-based analysis of existing GIS data layers. The remaining attributes require field-based methods for assessment. We were forced to exclude a small number of attributes from field tests due to inconsistent data (pesticide application rate, environmental contaminant concentrations) or requirements that exceeded the scope of this project (change in marsh surface elevation; surface topography; benthic invertebrates; wintering birds). We evaluated potential metrics for evaluating all remaining field attributes. In partnership with NWRS biologists, we tested rapid versus intensive metrics for monitoring field attributes (tidal range and groundwater level; marsh surface elevation; salinity; and species composition and abundance of vegetation, invasive species, nekton, and breeding birds) at coastal refuges throughout FWS Region 5. Seven refuges participated in metric testing in 2008: Rachel Carson (ME), Parker River (MA), Wertheim (NY), E. B. Forsythe
White Phosphorus Poisoning of Waterfowl in an Alaskan Salt Marsh
Charles H. Racine; Marianne E. Walsh; Bill D. Roebuck; Charles M. Collins; Darryl Calkins
The cause of the yearly death of an estimated 1,000 to 2,000 migrating dabbling ducks (Anas spp.) and 10 to 50 swans (Cygnus buccinator and C. columbianus) has remained a mystery for the last ten years in Eagle River Flats (ERF), a 1,000 ha estuarine salt marsh near Anchorage, Alaska, used for artillery training by the U.S. Army. We have
Suitability of different salt marsh plants for petroleum hydrocarbons remediation
M. Nazarķ P. F. S. Couto; M. Clara P. Basto; M. Teresa S. D. Vasconcelos
The suitability of the salt-marsh species Halimione portulacoides, Scirpus maritimus, Juncus maritimus and an association of the last two for remediation of petroleum hydrocarbons (PHC) in soil was investigated. An outdoor laboratory experiment (microcosm-scale) was carried out using contaminated soil collected in a refinery, as a complement of another study carried out in the refinery environment (mesocosm-scale). Soil samples with
Disturbance and Recovery of Salt Marsh Arthropod Communities following BP Deepwater Horizon Oil Spill
McCall, Brittany D.; Pennings, Steven C.
Oil spills represent a major environmental threat to coastal wetlands, which provide a variety of critical ecosystem services to humanity. The U.S. Gulf of Mexico is a hub of oil and gas exploration activities that historically have impacted intertidal habitats such as salt marsh. Following the BP Deepwater Horizon oil spill, we sampled the terrestrial arthropod community and marine invertebrates found in stands of Spartina alterniflora, the most abundant plant in coastal salt marshes. Sampling occurred in 2010 as oil was washing ashore and a year later in 2011. In 2010, intertidal crabs and terrestrial arthropods (insects and spiders) were suppressed by oil exposure even in seemingly unaffected stands of plants; however, Littoraria snails were unaffected. One year later, crab and arthropods had largely recovered. Our work is the first attempt that we know of assessing vulnerability of the salt marsh arthropod community to oil exposure, and it suggests that arthropods are both quite vulnerable to oil exposure and quite resilient, able to recover from exposure within a year if host plants remain healthy. PMID:22412916
Disturbance and recovery of salt marsh arthropod communities following BP Deepwater Horizon oil spill.
McCall, Brittany D; Pennings, Steven C
Oil spills represent a major environmental threat to coastal wetlands, which provide a variety of critical ecosystem services to humanity. The U.S. Gulf of Mexico is a hub of oil and gas exploration activities that historically have impacted intertidal habitats such as salt marsh. Following the BP Deepwater Horizon oil spill, we sampled the terrestrial arthropod community and marine invertebrates found in stands of Spartina alterniflora, the most abundant plant in coastal salt marshes. Sampling occurred in 2010 as oil was washing ashore and a year later in 2011. In 2010, intertidal crabs and terrestrial arthropods (insects and spiders) were suppressed by oil exposure even in seemingly unaffected stands of plants; however, Littoraria snails were unaffected. One year later, crab and arthropods had largely recovered. Our work is the first attempt that we know of assessing vulnerability of the salt marsh arthropod community to oil exposure, and it suggests that arthropods are both quite vulnerable to oil exposure and quite resilient, able to recover from exposure within a year if host plants remain healthy. PMID:22412916
Distribution and metabolism of quaternary amines in salt marshes
NASA Technical Reports Server (NTRS)
King, Gary M.
Quaternary amines such as glycine betaine (GBT) are common osmotically active solutes in much of the marine biota. GBT is accumulated by various bacteria, algae, higher plants, invertebrates, and vertebrates in response to salinity or water stresses; in some species, GBT occurs at tens to hundreds of millimolar concentrations and can account for a significant fraction of total nitrogen. Initial studies suggest that GBT is readily converted to two potential methane precursors, trimethylamine (TMA) and acetate, in anoxic sediments. TMA is apparently the most important methane precursor in surface sediments containing sulfate reducing bacteria. In salt marshes, the bulk of the methane formed may be due to the metabolism of TMA rather than other substrates. Current research is focussed on testing this hypothesis and on determining the role of quaternary amino osmoregulatory solutes in methane fluxes from marine environments. Preliminary studies have dealt with several problems: (1) determination of GBT concentrations in the dominant flora and fauna of salt marshes; (2) synthesis of radiolabelled GBT for metabolic studies; and (3) determination of fates of BGT in marine sediments using radiotracers. Both GC and HPLC techniques have been used to assay GBT concentrations in plant and animal tissues. S. alterniflora is probably the only significant source of GBT (and indirectly of methane) since the biomass and distribution of most other species is limited. Current estimates suggest that S. alterniflora GBT could account for most of the methane efflux from salt marshes.
Consequences of climate change, eutrophication, and other anthropogenic impacts to coastal salt marshes: multiple stressors reduce resiliency and sustainability
NASA Astrophysics Data System (ADS)
Watson, E. B.; Wigand, C.; Nelson, J.; Davey, E.; Van Dyke, E.; Wasson, K.
Coastal salt marshes provide a wide variety of ecosystem services, including habitat for protected vertebrates and ecologically valuable invertebrate fauna, flood protection, and improvements in water quality for adjacent marine and estuarine environments. Here, we consider the impacts of future sea level rise combined with other anthropogenic stressors to salt marsh sustainability through the implementation of field and laboratory mesocosms, manipulative experiments, correlative studies, and predictive modeling conducted in central California and southern New England salt marshes. We report on measurements of soil respiration, decomposition, sediment accumulation, and marsh elevation, which considered jointly suggest an association between nitrate input and marsh elevation loss resulting from mineralization of soil organic matter. Furthermore, use of imaging techniques (CT scans) has shown differences in belowground root and rhizome structure associated with fertilization, resulting in a loss of sediment cohesion promoted by fine root structure. Additionally, field and greenhouse mesocosm experiments have provided insight into the specific biogeochemical processes responsible for plant mortality at high immersion or salinity levels. In conclusion, we have found that poor water quality (i.e. eutrophication) leads to enhanced respiration and decomposition of soil organic matter, which ultimately contributes to a loss of salt marsh sustainability. However, marsh deterioration studied at field sites (Jamaica Bay, NY and Elkhorn Slough, CA) is associated not only with enhanced nutrient loads, but also increased immersion due to tidal range increases resulting from dredging. To ensure the continuation of the ecosystem services provided by tidal wetlands and to develop sustainable management strategies that provide favorable outcomes under a variety of future sea level rise and land use scenarios, we need to develop a better understanding of the relative impacts of the various stressors leading to salt marsh loss. Without this understanding, costly remediation may unintentionally lead to continued marsh deterioration. More research is needed to carefully document the positive and negative aspects of nutrient loading to coastal marsh sustainability in order to ensure that coastal watersheds are managed in a way that minimizes detrimental impacts to adjacent coastal habitats, while not interfering unnecessarily with important and needed public interest activities such as agriculture and wastewater discharge.
Response of Salt Marsh Ponds to Eutropication Austin N. Ritter1,3
Vallino, Joseph J.
Response of Salt Marsh Ponds to Eutropication Austin N. Ritter1,3 , David Dodge1 , Linda A. Deegan2 examined the response of New England salt marsh ponds to nutrient loading via flooding tidal water as part of nutrient (70 uM nitrate and 4uM phosphate). Our results indicate that gross nitrate processing in salt
Evaluation of white plastic flags as visual repellents for Snow Geese on coastal salt marshes
J. Russell Mason
Excessive grazing by Snow Geese (Chen caerulescens) causes severe damage to salt marshes along the eastern seaboard of the United States and to traditional agricultural practices such as salt hay farming. The effectiveness of white plastic flags as visual repellents to Snow Geese (Chen caerulescens) on six Delaware Bay salt hay (Spartina sp.) marshes was evaluated. At each site, two
Differential responses of tidal marsh area and delivery of ecosystem services to rising sea level
Cai, Wei-Jun
%, respectively, by 2100. However, the reduction in ecosystem services, primary production (macrophyte abovegroundDifferential responses of tidal marsh area and delivery of ecosystem services to rising sea level, and coastal wetlands, tidal marshes and mangroves provide ecosystem services that benefit these coastal
Dual role of salt marsh retreat: Long-term loss and short-term resilience
NASA Astrophysics Data System (ADS)
Mariotti, G.; Carr, J.
Two major causes of salt marsh loss are vertical drowning, when sediment accumulation on the platform cannot keep vertical pace with sea level rise, and horizontal retreat, associated with wave-induced marsh boundary erosion. Despite these processes having been extensively documented and modeled, it is unclear which loss modality dominates given a set of environmental parameters. A three-point dynamic model was developed to predict marsh loss as a function of sea level rise, allochthonous sediment supply, wind regime, tidal range, and marsh bank and mudflat erodability. Marsh horizontal and vertical evolutions were found to respond in opposing ways to wave-induced erosion processes. Marsh horizontal retreat was triggered by large mudflats, strong winds, high erodability of marsh bank and mudflat, whereas the opposite conditions acted to reduce the sediment supply to the marsh platform, promoting marsh loss to drowning. With low and moderate rates of sea level rise (ś5 mm/yr), retreat was found to be a more likely marsh loss modality than drowning. However, conditions associated with marsh retreat also increase the system resilience by transferring sediment on the marsh platform and preventing drowning. Our results suggest the use of a modular strategy for short-term marsh management: selectively protect extensive salt marsh regions by maintaining healthy vegetation on the platform, while allowing other areas to retreat, leveraging the natural resilience embedded in the lateral loss of marsh extent.
Salt marsh as a coastal filter for the oceans: changes in function with experimental increases in nitrogen loading and sea-level rise.
Nelson, Joanna L; Zavaleta, Erika S
Coastal salt marshes are among Earth's most productive ecosystems and provide a number of ecosystem services, including interception of watershed-derived nitrogen (N) before it reaches nearshore oceans. Nitrogen pollution and climate change are two dominant drivers of global-change impacts on ecosystems, yet their interacting effects at the land-sea interface are poorly understood. We addressed how sea-level rise and anthropogenic N additions affect the salt marsh ecosystem process of nitrogen uptake using a field-based, manipulative experiment. We crossed simulated sea-level change and ammonium-nitrate (NH(4)NO(3))-addition treatments in a fully factorial design to examine their potentially interacting effects on emergent marsh plants in a central California estuary. We measured above- and belowground biomass and tissue nutrient concentrations seasonally and found that N-addition had a significant, positive effect on a) aboveground biomass, b) plant tissue N concentrations, c) N stock sequestered in plants, and d) shoot:root ratios in summer. Relative sea-level rise did not significantly affect biomass, with the exception of the most extreme sea-level-rise simulation, in which all plants died by the summer of the second year. Although there was a strong response to N-addition treatments, salt marsh responses varied by season. Our results suggest that in our site at Coyote Marsh, Elkhorn Slough, coastal salt marsh plants serve as a robust N trap and coastal filter; this function is not saturated by high background annual N inputs from upstream agriculture. However, if the marsh is drowned by rising seas, as in our most extreme sea-level rise treatment, marsh plants will no longer provide the ecosystem service of buffering the coastal ocean from eutrophication. PMID:22879873
Salt Marsh as a Coastal Filter for the Oceans: Changes in Function with Experimental Increases in Nitrogen Loading and Sea-Level Rise
Nelson, Joanna L.; Zavaleta, Erika S.
Coastal salt marshes are among Earth's most productive ecosystems and provide a number of ecosystem services, including interception of watershed-derived nitrogen (N) before it reaches nearshore oceans. Nitrogen pollution and climate change are two dominant drivers of global-change impacts on ecosystems, yet their interacting effects at the land-sea interface are poorly understood. We addressed how sea-level rise and anthropogenic N additions affect the salt marsh ecosystem process of nitrogen uptake using a field-based, manipulative experiment. We crossed simulated sea-level change and ammonium-nitrate (NH4NO3)-addition treatments in a fully factorial design to examine their potentially interacting effects on emergent marsh plants in a central California estuary. We measured above- and belowground biomass and tissue nutrient concentrations seasonally and found that N-addition had a significant, positive effect on a) aboveground biomass, b) plant tissue N concentrations, c) N stock sequestered in plants, and d) shoot:root ratios in summer. Relative sea-level rise did not significantly affect biomass, with the exception of the most extreme sea-level-rise simulation, in which all plants died by the summer of the second year. Although there was a strong response to N-addition treatments, salt marsh responses varied by season. Our results suggest that in our site at Coyote Marsh, Elkhorn Slough, coastal salt marsh plants serve as a robust N trap and coastal filter; this function is not saturated by high background annual N inputs from upstream agriculture. However, if the marsh is drowned by rising seas, as in our most extreme sea-level rise treatment, marsh plants will no longer provide the ecosystem service of buffering the coastal ocean from eutrophication. PMID:22879873
Sarah Robinson; Danika van Proosdij; Hank Kolstee
This paper presents preliminary results of a research program designed to examine the change in dykeland practices in agricultural salt marsh of Cobequid Bay in the Bay of Fundy and document the observed changes of the marshes in response to these modifications. The area of study in Cobequid Bay contains twelve marsh bodies each with dykes and aboiteaux maintained by
Plant zonation in low-latitude salt marshes: disentangling the roles of flooding, salinity and competition
Summary 1 We investigated the factors producing zonation patterns of the dominant plants in south-eastern USA salt marshes where Juncus roemerianus dominates the high marsh, and Spartina alterniflora the middle and low marsh. 2 Juncus did not occur naturally in the Spartina zone and performed poorly when trans- planted there, irrespective of whether neighbours were present or removed, indicating that
Vulnerability of Northeastern U.S. Salt Marshes to Climatic and Anthropogenic Stressors (AGU)
In the Northeastern U.S., salt marsh area is in decline. Habitat change analysis has revealed fragmentation, displacement of high marsh by low marsh species, and ecological drowning, while development of adjacent uplands limits upslope migration. Using inundation experiments, fi...
Ecological engineering, adaptive management, and restoration management in Delaware Bay salt marsh restoration
John M. Teal; Lee Weishar
Salt hay marshes were diked and farmed for over 50 years, reducing marsh plain elevations, obliterating many tidal channels, keeping fish out of the marsh, and encouraging invasion of Phragmites. Restoration involved setting restoration goals, careful planning, recreating major tidal channels, and opening the dikes. Ecological engineering, allowing nature to self-design, was used to create the smaller tidal channels, re-introduce
Differential response of salt-marsh species to variation of iron and manganese
J. Rozema; E. Luppes; R. Broekman
Salt-marsh plants of the lower, middle and upper marsh were compared in their response to iron and manganese. The species studied showed differential sensitivity to high concentrations of Fe (1 000 ĄM) and Mn (10 000 ĄM) in hydroculture experiments, species of the lower marsh being more resistant than species of the upper marsh. Fe and Mn concentrations in the
Stratigraphic and Ecophysical Characterizations of Salt Pools: Dynamic Landforms of the Webhannet Salt Marsh, Wells, ME, USA
Kristin R. Wilson; Joseph T. Kelley; Arie Croitoru; Michele Dionne; Daniel F. Belknap; Robert Steneck
Salt pools are water-filled depressions common to north-temperate salt marshes. In Wells, ME, USA, cores reveal a unique salt\\u000a pool signature consisting of water-saturated dark-gray mud often containing fragments of Ruppia maritima. Cores through pool sediment reenter salt marsh peat, not tidal flat sediment, demonstrating that most pools are of secondary\\u000a origin. A principal component analysis of attribute data collected
Rhizosphere heterogeneity shapes abundance and activity of sulfur-oxidizing bacteria in vegetated salt marsh sediments
Thomas, Franńois; Giblin, Anne E.; Cardon, Zoe G.; Sievert, Stefan M.
Salt marshes are highly productive ecosystems hosting an intense sulfur (S) cycle, yet little is known about S-oxidizing microorganisms in these ecosystems. Here, we studied the diversity and transcriptional activity of S-oxidizers in salt marsh sediments colonized by the plant Spartina alterniflora, and assessed variations with sediment depth and small-scale compartments within the rhizosphere. We combined next-generation amplicon sequencing of 16S rDNA and rRNA libraries with phylogenetic analyses of marker genes for two S-oxidation pathways (soxB and rdsrAB). Gene and transcript numbers of soxB and rdsrAB phylotypes were quantified simultaneously, using newly designed (RT)-qPCR assays. We identified a diverse assemblage of S-oxidizers, with Chromatiales and Thiotrichales being dominant. The detection of transcripts from S-oxidizers was mostly confined to the upper 5 cm sediments, following the expected distribution of root biomass. A common pool of species dominated by Gammaproteobacteria transcribed S-oxidation genes across roots, rhizosphere, and surrounding sediment compartments, with rdsrAB transcripts prevailing over soxB. However, the root environment fine-tuned the abundance and transcriptional activity of the S-oxidizing community. In particular, the global transcription of soxB was higher on the roots compared to mix and rhizosphere samples. Furthermore, the contribution of Epsilonproteobacteria-related S-oxidizers tended to increase on Spartina roots compared to surrounding sediments. These data shed light on the under-studied oxidative part of the sulfur cycle in salt marsh sediments and indicate small-scale heterogeneities are important factors shaping abundance and potential activity of S-oxidizers in the rhizosphere. PMID:25009538
Loss of 'blue carbon' from coastal salt marshes following habitat disturbance.
Macreadie, Peter I; Hughes, A Randall; Kimbro, David L
Increased recognition of the global importance of salt marshes as 'blue carbon' (C) sinks has led to concern that salt marshes could release large amounts of stored C into the atmosphere (as CO2) if they continue undergoing disturbance, thereby accelerating climate change. Empirical evidence of C release following salt marsh habitat loss due to disturbance is rare, yet such information is essential for inclusion of salt marshes in greenhouse gas emission reduction and offset schemes. Here we investigated the stability of salt marsh (Spartinaalterniflora) sediment C levels following seagrass (Thallasiatestudinum) wrack accumulation; a form of disturbance common throughout the world that removes large areas of plant biomass in salt marshes. At our study site (St Joseph Bay, Florida, USA), we recorded 296 patches (7.5 ▒ 2.3 m(2) mean area ▒ SE) of vegetation loss (aged 3-12 months) in a salt marsh meadow the size of a soccer field (7 275 m(2)). Within these disturbed patches, levels of organic C in the subsurface zone (1-5 cm depth) were ~30% lower than the surrounding undisturbed meadow. Subsequent analyses showed that the decline in subsurface C levels in disturbed patches was due to loss of below-ground plant (salt marsh) biomass, which otherwise forms the main component of the long-term 'refractory' C stock. We conclude that disturbance to salt marsh habitat due to wrack accumulation can cause significant release of below-ground C; which could shift salt marshes from C sinks to C sources, depending on the intensity and scale of disturbance. This mechanism of C release is likely to increase in the future due to sea level rise; which could increase wrack production due to increasing storminess, and will facilitate delivery of wrack into salt marsh zones due to higher and more frequent inundation. PMID:23861964
Degradation of malathion by salt-marsh microorganisms.
Bourquin, A W
Numerous bacteria from a salt-marsh environment are capable of degrading malathion, an organophosphate insecticide, when supplied with additional nutrients as energy and carbon sources. Seven isolates exhibited ability (48 to 90%) to degrade malathion as a sole carbon source. Gas and thin-layer chromatography and infrared spectroscopy confirmed malathion to be degraded via malathion-monocarboxylic acid to the dicarboxylic acid and then to various phosphothionates. These techniques also identified desmethyl-malathion, phosphorthionates, and four-carbon dicarboxylic acids as degradation products formed as a result of phosphatase activity. PMID:192147
Landscape Patterns of Forb Pannes Across a Northern New England Salt Marsh
Pamela Jayne Griffin; Theresa Theodose; Michele Dionne
Most salt marshes are dominated by graminoids, but patches dominated by a diverse assemblage of perennial forbs, known as\\u000a forb pannes, occur on marshes in north temperate areas. These pannes and their associated species diversity appear to be highly\\u000a responsive to anthropogenic change, including climate warming. We mapped all of the forb pannes on a salt marsh in Wells,\\u000a Maine
The geochemistry of salt marshes: Sedimentary ion diffusion, sulfate reduction, and pyritization
Abstract-A series of seasonal cores was taken in a high marsh near the terminus of Delaware Bay, U.S.A. A seasonal harmonic,diffusion model was successfully fit to the concentration,profiles of chloride ion in the salt marsh,pore waters yielding a calculated sedimentary,diffusion coefficient. Virtually all other chemical,reactions within salt marsh,sediments,are directly linked to the rate and stoichiometry,of organic decomposition.,The rich organic input
Gas exchange in the salt marsh species Atriplex portulacoides L. and Limoniastrum monopetalum L. in Southern Portugal
JoŃo Pedro Correia das Neves; LuĒs Filipe Portugal Ferreira; Maria Margarida Vaz; Luiz Carlos Gazarini
Salt marshes are ecosystems subjected to a variety of environmental stresses like high salinity, water deficit, intense radiation\\u000a or high temperatures. Field measurements were conduced in two halophyte species, Atriplex portulacoides L. and Limoniastrum monopetalum L., in the Reserva Natural do Sapal de Castro Marim, to compare their physiological response, i.e., water potential (?),\\u000a net photosynthetic rate (A), stomatal conductance
Estimates of future inundation of salt marshes in response to sea-level rise in and around Acadia National Park, Maine
Nielsen, Martha G.; Dudley, Robert W.
Salt marshes are ecosystems that provide many important ecological functions in the Gulf of Maine. The U.S. Geological Survey investigated salt marshes in and around Acadia National Park from Penobscot Bay to the Schoodic Peninsula to map the potential for landward migration of marshes using a static inundation model of a sea-level rise scenario of 60 centimeters (cm; 2 feet). The resulting inundation contours can be used by resource managers to proactively adapt to sea-level rise by identifying and targeting low-lying coastal areas adjacent to salt marshes for conservation or further investigation, and to identify risks to infrastructure in the coastal zone. For this study, the mapping of static inundation was based on digital elevation models derived from light detection and ranging (LiDAR) topographic data collected in October 2010. Land-surveyed control points were used to evaluate the accuracy of the LiDAR data in the study area, yielding a root mean square error of 11.3 cm. An independent accuracy assessment of the LiDAR data specific to salt-marsh land surfaces indicated a root mean square error of 13.3 cm and 95-percent confidence interval of ▒ 26.0 cm. LiDAR-derived digital elevation models and digital color aerial photography, taken during low tide conditions in 2008, with a pixel resolution of 0.5 meters, were used to identify the highest elevation of the land surface at each salt marsh in the study area. Inundation contours for 60-cm of sea-level rise were delineated above the highest marsh elevation for each marsh. Confidence interval contours (95-percent,▒ 26.0 cm) were delineated above and below the 60-cm inundation contours, and artificial structures, such as roads and bridges, that may present barriers to salt-marsh migration were mapped. This study delineated 114 salt marshes totaling 340 hectares (ha), ranging in size from 0.11 ha (marshes less than 0.2 ha were mapped only if they were on Acadia National Park property) to 52 ha, with a median size of 1.0 ha. Inundation contours were mapped at 110 salt marshes. Approximately 350 ha of low-lying upland areas adjacent to these marshes will be inundated with 60 cm of sea-level rise. Many of these areas are currently freshwater wetlands. There are potential barriers to marsh migration at 27 of the 114 marshes. Although only 23 percent of the salt marshes in the study are on ANP property, about half of the upland areas that will be inundated are within ANP; most of the predicted inundated uplands (approximately 170 ha) include freshwater wetlands in the Northeast Creek and Bass Harbor Marsh areas. Most of the salt marshes analyzed do not have a significant amount of upland area available for migration. Seventy-five percent of the salt marshes have 20 meters or less of adjacent upland that would be inundated along most of their edges. All inundation contours, salt marsh locations, potential barriers, and survey data are stored in geospatial files for use in a geographic information system and are a part of this report.
Assessing Wildlife Habitat Value of New England Salt Marshes: II. Model Testing and Validation
We test a previously described model to assess the wildlife habitat value of New England salt marshes by comparing modeled habitat values and scores with bird abundance and species richness at sixteen salt marshes in Narragansett Bay, Rhode Island USA. Assessment scores ranged f...
Sedimentation rates and heavy metals in a macrotidal salt marsh: Bay of Fundy, Canada
Ray Kostaschuk; Zhongyuan Chen; Yoshiki Saito; Zhangqiao Wang
Macrotidal salt marshes play an important role in sedimentary processes in estuaries and can act as a sink for fine sediments and contaminants. This study examines sedimentation rates and the history of heavy metal accumulation in the Allen Creek salt marsh in the Bay of Fundy, Canada. Pb-210 and Cs-137 measurements and accelerated mass spectrometer (AMS) dating indicate a sedimentation
Vulnerability of Rhode Island Salt Marshes to Sea Level Rise and Poor Water Quality
Across the northeastern Unites States, salt marshes are losing ground. Edges are eroding, tidal channel networks are expanding, and new ponds are forming and expanding within salt marshes. This leaves shorelines - and in some cases houses - more vulnerable to nor'easters and tr...
The role of succulent halophytes in the water balance of salt marsh rodents
Harry N. Coulombe
The role of succulent halophytes in the water balance and ecology of salt marsh rodents is dependent upon an evaluation of the composition of the available sources and the physiological properties of their potential consumers. Studies of the osmotic properties of succulent halophytes from southern California coastal salt marshes are presented, together with experiments regarding the utilization of Common Pickleweed
Spontaneous tidal network formation within a constructed salt marsh: Observations and morphodynamic modelling
Andrea D'Alpaos; Stefano Lanzoni; Marco Marani; Andrea Bonometto; Giovanni Cecconi; Andrea Rinaldo
We have monitored and analyzed, through remote sensing and ancillary field surveys, the rapid (O(1) year) development of a tidal network within a newly established artificial salt marsh in the Venice Lagoon. After the construction of the salt marsh, a network of volunteer creeks established themselves away from an artificially constructed main channel (with mean and maximum annual headward-growth rates
Quantification of Ammonia-Oxidizing Bacteria and Factors Controlling Nitrification in Salt Marsh Sediments
Sherry L. Dollhopf; Jung-Ho Hyun; April C. Smith; Harold J. Adams; Sean O'Brien; Joel E. Kostka
To elucidate the geomicrobiological factors controlling nitrification in salt marsh sediments, a comprehen- sive approach involving sediment geochemistry, process rate measurements, and quantification of the genetic potential for nitrification was applied to three contrasting salt marsh habitats: areas colonized by the tall (TS) or short (SS) form of Spartina alterniflora and unvegetated creek banks (CBs). Nitrification and denitrification potential rates
Relationships Between Watershed Emergy Flow and Coastal New England Salt Marsh Structure, Function, and Condition
This study evaluated the link between watershed activities and salt marsh structure, function, and condition using spatial emergy flow density (areal empower density) in the watershed and field data from 10 tidal salt marshes in Narragansett Bay, RI. The field-collected data wer...
Competition and herbivory during salt marsh succession: the importance of forb growth strategy
Carsten F. Dormann; Rene Van Der Wal; Jan P. Bakker
Summary 1 Despite much debate about their importance, only a few field studies have evalu- ated the intensity of competition and herbivory. 2 Artemisia maritima, Atriplex portulacoides and Plantago maritima, three plant species which are common in European temperate salt marshes, were transplanted into di─erent successional stages (15, 30 and 45 years old) of a temperate salt marsh. Biomass of
Effects of Nitrate Fertilization on Pyrite Oxidation in Salt Marsh Sediments Ben Pyenson1
Vallino, Joseph J.
Effects of Nitrate Fertilization on Pyrite Oxidation in Salt Marsh Sediments Ben Pyenson1 Advisor;Pyenson 2 Abstract: Pyrite oxidation and NO3- loading to estuaries present unique environmental problems studied the effects of NO3- fertilization on pyrite oxidation in salt marshes with the hypothesis that NO3
Copper and lead concentrations in salt marsh plants on the Suir Estuary, Ireland
E. J Fitzgerald; J. M Caffrey; S. T Nesaratnam; P McLoughlin
Concentrations of Cu and Pb were determined in the roots and shoots of six salt marsh plant species, and in sediment taken from between the roots of the plants, sampled from the lower salt marsh zone at four sites along the Suir Estuary in autumn 1997. Cu was mainly accumulated in the roots of monocotyledonous and dicotyledonous species. Pb was
Diet choice in an omnivorous salt-marsh crab: different food types, body size,
Pennings, Steven C.
Diet choice in an omnivorous salt-marsh crab: different food types, body size, and habitat 24 February 2003; accepted 18 March 2003 Abstract Studies of diet choice by omnivores have, and predators. We examined diet choice in the omnivorous salt marsh crab Armases cinereum ( = Sesarma cinereum
Salt marsh habitat integrity is linked with the ability to provide good water quality and high biodiversity. We measured high denitrification enzyme activity (DEA) in ten coastal salt marshes in Narragansett Bay, Rhode Island (seasonal means ranging from 7,476 - 53,494 kg N-1ha-...
Vallino, Joseph J.
THE EFFECT OF DOMINANT GRASS SPECIES ON NITROGEN CYCLING IN GREAT SIPPEWISSETT SALT MARSH SEDIMENTS ABSTRACT Salt marsh productivity and nitrogen cycling are tightly linked processes that can be affected species influence the rate of nitrogen cycling in the sediments and, in turn, the overall productivity
Disturbance and Recovery of Salt Marsh Arthropod Communities following BP Deepwater Horizon Oil Spill
Pennings, Steven C.
of Houston, Houston, Texas, United States of America Abstract Oil spills represent a major environmental intertidal habitats such as salt marsh. Following the BP Deepwater Horizon oil spill, we sampled and Recovery of Salt Marsh Arthropod Communities following BP Deepwater Horizon Oil Spill. PLoS ONE 7(3): e
Biotic interactions mediate the expansion of black mangrove (Avicennia germinans) into salt marshes under
Pennings, Steven C.
Biotic interactions mediate the expansion of black mangrove (Avicennia germinans) into salt marshes of Mexico coast, USA, subtropical black mangrove (Avicennia germinans) at the northern limit of its decades, freeze-free winters have led to an expansion of black mangrove into salt marshes. We examined how
Effects of Nitrate on Decomposition in Salt Marsh Peats Arianna Goodman
Vallino, Joseph J.
Effects of Nitrate on Decomposition in Salt Marsh Peats Arianna Goodman Oberlin College `13 Advisor and loss. Rapid nitrate addition to salt marshes may stimulate bacterial decomposition of existing peat, and the decomposition may contribute to creek bank destabilization and collapse. Alternately, peat deposited in high
Recovery of a northern New England salt marsh plant community from winter icing
Patrick J. Ewanchuk; Mark D. Bertness
High latitude salt marsh plant communities are frequently exposed to conspicuous winter ice disturbances, which trigger secondary succession. In this paper, we document the recovery of a northern New England salt marsh from a severe winter icing event in 1998. Ice disturbances that killed plants but that left the underlying peat intact recovered rapidly. However, ice damage that killed plants
Coastal salt marshes are susceptible to cultural eutrophication, particularly the over-enrichment of nitrogen, because they are often located where surface water and groundwater discharge into estuaries. In this report, the current areal extent of coastal salt marshes in Narrag...
Candidate Tsunami Deposits at Carpinteria Salt Marsh, Southern California
NASA Astrophysics Data System (ADS)
Peters, R.; Jaffe, B. E.; Buckley, M.; Watt, S. G.
Carpinteria Salt Marsh, 15 km southeast of Santa Barbara, California preserves geologic evidence of possible past tsunami inundation along the southern California coast. The proximity of the Santa Barbara coastline to the Goleta slide complex and to numerous offshore faults in the Santa Barbara basin suggests a potential for moderate to large tsunamis. A field investigation in February 2008 collected more than 60 cores and examined 8 cutbank exposures throughout the marsh. Sand layers consistent with tsunami deposition were found at depths from 35 to 96 cm in cores from four areas within the marsh. The sand layers, which range from 1 cm to 35 cm thick and extend up to 630 m inland, had sharp lower contacts and were often normally graded. In addition, in some cores there were one or more intervening mud layers within the sand layer. Composition and angularity of the sand is similar to sands found in the surrounding beach, dune, and nearshore environments. While the sand layers occur at similar depths in the cores, they were concentrated in four areas that were isolated by regions with no evidence of tsunami deposition. The deposits may represent spatially discontinuous deposition from one event, spatially continuous deposition from one event with poor preservation of the deposits, or deposition from more than one event. Discontinuous deposition from one event is in contrast to spatially continuous sheet deposition characteristic of moderate to large tsunamis, but may represent isolated deposition by a smaller tsunami along channel banks. The deposit is more consistent with tsunami deposition than deposition by other event-driven processes such as storms or floods. However, marsh processes that may create normally graded sand layers such as channel migration must also be considered before accepting a tsunami origin for the deposits.
Ionic alkylleads in salt marsh periwinkles (Littorina irrorata)
Krishnan, K.; Marshall, W.D.; Hatch, W.I.
Salt marsh periwinkles (Littorina irrorata), from six sites in Maryland and Virginia, were examined to determine ionic alkyllead concentrations and possible alkyllead sources in lower Chesapeake Bay. Different sources of ethylleads and trimethyllead to this species were demonstrated by statistical comparisons of the concentrations of individual analytes from different sites. These comparisons also indicated (1) that environmentally mediated methylation of Pb/sup 2 +/ contributes appreciably to Me/sub 3/Pb/sup +/ concentrations in snails and (2) that the relative concentrations of individual analytes were consistent with an environmental methylation of ethyllead salts. Compared to females, males were characterized by significantly higher concentrations of several of the alkyllead analytes. In addition, an unknown lead-containing compound was present in all samples.
Impact of Fertilization on a Salt Marsh Food Web in Georgia Caroline R. McFarlin & J. Stephen Brewer &
Pennings, Steven C.
, these results suggest that eutrophication of salt marshes is likely to have stronger impacts on plants marshes focused on the performance of single plant species in monoculture, and demonstrated that saltImpact of Fertilization on a Salt Marsh Food Web in Georgia Caroline R. McFarlin & J. Stephen
Feeding Ecology of 0-Group Sea Bass, Dicentrarchus labrax, in Salt Marshes of Mont Saint Michel Bay (France)
Paris-Sud XI, Universitķ de
and refuge provided by vascular plants. By comparison, fish communities using European salt marshes are lessFeeding Ecology of 0-Group Sea Bass, Dicentrarchus labrax, in Salt Marshes of Mont Saint Michel Bay% of the tides. It was shown that primary and secondary production of intertidal salt marshes play a fundamental
Biogeochemical drivers of phosphatase activity in salt marsh sediments
NASA Astrophysics Data System (ADS)
Freitas, Joana; Duarte, Bernardo; Cańador, Isabel
Although nitrogen has become a major concern for wetlands scientists dealing with eutrophication problems, phosphorous represents another key element, and consequently its biogeochemical cycling has a crucial role in eutrophication processes. Microbial communities are a central component in trophic dynamics and biogeochemical processes on coastal systems, since most of the processes in sediments are microbial-mediated due to enzymatic action, including the mineralization of organic phosphorus carried out by acid phosphatase activity. In the present work, the authors investigate the biogeochemical sediment drivers that control phosphatase activities. Authors also aim to assess biogeochemical factors' influence on the enzyme-mediated phosphorous cycling processes in salt marshes. Plant rhizosediments and bare sediments were collected and biogeochemical features, including phosphatase activities, inorganic and organic phosphorus contents, humic acids content and pH, were assessed. Acid phosphatase was found to give the highest contribution for total phosphatase activity among the three pH-isoforms present in salt marsh sediments, favored by acid pH in colonized sediments. Humic acids also appear to have an important role inhibiting phosphatase activity. A clear relation of phosphatase activity and inorganic phosphorous was also found. The data presented reinforces the role of phosphatase in phosphorous cycling.
White phosphorus poisoning of waterfowl in an Alaskan salt marsh.
Racine, C H; Walsh, M E; Roebuck, B D; Collins, C M; Calkins, D; Reitsma, L; Buchli, P; Goldfarb, G
The cause of the yearly death of an estimated 1,000 to 2,000 migrating dabbling ducks (Anas spp.) and 10 to 50 swans (Cygnus buccinator and C. columbianus) has remained a mystery for the last ten years in Eagle River Flats (ERF), a 1,000 ha estuarine salt marsh near Anchorage, Alaska, used for artillery training by the U.S. Army. We have gathered evidence that the cause of this mortality is the highly toxic, incendiary munition white phosphorus (P4). The symptoms of poisoning we observed in wild ducks included lethargy, repeated drinking, and head shaking and rolling. Death was preceded by convulsions. Farm-reared mallards dosed with white phosphorus showed nearly identical behavioral symptoms to those of wild ducks that became sick in ERF. White phosphorus does not occur in nature but was found in both the sediments where dabbling ducks and swans feed and in the gizzards of all carcasses collected in ERF. We hypothesize that feeding waterfowl are ingesting small particles of the highly toxic, incendiary munition P4 stored in the bottom anoxic sediments of shallow salt marsh ponds. PMID:1474672
Suitability of different salt marsh plants for petroleum hydrocarbons remediation.
Couto, M Nazarķ P F S; Basto, M Clara P; Vasconcelos, M Teresa S D
The suitability of the salt-marsh species Halimione portulacoides, Scirpus maritimus, Juncus maritimus and an association of the last two for remediation of petroleum hydrocarbons (PHC) in soil was investigated. An outdoor laboratory experiment (microcosm-scale) was carried out using contaminated soil collected in a refinery, as a complement of another study carried out in the refinery environment (mesocosm-scale). Soil samples with old contamination (mainly crude oil) and with a mixture of the old and recent (turbine oil) contamination were tested. Studies in both micro- and mesocosm-scale provided results coherent in substance. The presence of S. maritimus caused removal of old contamination which was refractory to natural attenuation (after 7months of exposure, efficiency was 13% when only old contamination was present and 40% when the soil also contained recent contamination). H. portulacoides (only included in the microcosm-scale study) revealed also potentiality for PHC remediation, although with less efficiency than S. maritimus. Degradation of recent contamination was also faster in the presence of plants (after 7months: 100% in the presence of S. maritimus vs. 63% in its absence). As these species are common in salt marsh areas in Atlantic coast of Europe, it is probable they will be also useful for recovering coast sediments. In contrast, J. maritimus and association did not reveal capability to remove PHC from soil, the presence of J. maritimus inhibiting the capability of S. maritimus. PMID:21601235
Modeling Soil Salinity Distribution Along An Elevational Gradient In Tidal Salt Marshes In Atlantic And Gulf Coastal Regions
NASA Astrophysics Data System (ADS)
Wang, H.; Hsieh, P.; Harwell, M. A.
Soil pore water salinity plays a very important role in determining the distribution of vegetation, plant productivity and biogeochemical processes in estuarine ecosystems. Pore water salinity gradients and salinity-vegetation associations in salt marshes have often been observed but rarely explained. A quantitative and systematic study on the pore water salinity distribution in salt marshes is not only critical to the understanding of the phenomenon itself but also to the use of the phenomenon as a convenient ecological and environmental change indicator. In this research, we developed a salt marsh pore water salinity model based on a salt and water balance model with modifications to several key features (e.g., applying the Penman-Monteith equation to calculate ET for different climate zones) to examine the impacts of climate, tidal forcing, soil, vegetation, and topography on pore water salinity distribution along elevation in the Atlantic and Gulf coastal regions. This model was calibrated and validated using field observations from the St. Marks National Wildlife Refuge (NWR) of northwestern Florida, USA. The results showed that the model had good agreement (r2=0.84, n=15, P<0.001) with field observations. We found that the mean higher high water (MHHW) level determines the location of the salinity maximum along an elevational gradient, and the salinity maximum most likely occurs at an elevation approximately 25 cm above MHHW. Simulations indicate that tidal irregularity (defined as the standard deviation of tides in this study area) primarily controls the width of the salinity variation band (i.e., elevation range with soil salinity dramatically > incoming tidal salinity) along elevation. A standard deviation increase of 10 cm in tidal heights could result in an increase in salinity variation band by approximately 40 cm (mostly seaward). Moreover, ET, temperature, hydraulic conductivity, and incoming tidal salinity are the dominant factors determining the magnitude of the salinity maximum, which may lead to the occurrence of salt barrens/flats when reaching a threshold level (e.g., >70 ppt). Our analyses are important to understanding the effects of climate change and sea-level rise on the productivity and biogeochemical processes of salt marsh ecosystems by monitoring soil pore water salinity, an effective environmental indicator, over a salt marsh elevational gradient. Key words: Pore water salinity, Tide, Salt marsh, Elevational gradient, Model simulation, Atlantic and Gulf coasts
Salt Marsh Sediment Mixing Following Petroleum Hydrocarbon Exposure from the Deepwater Horizon Oil Spill
NASA Astrophysics Data System (ADS)
Hatch, R. S.; Yeager, K. M.; Brunner, C. A.; Wade, T. L.; Briggs, K. B.; Schindler, K. J.
Tidal marshes support valuable ecosystems, but their coastal locations make them susceptible to oil spills. Oil spilled in the ocean is easily transported via tidal and wind-driven currents to the shore and incorporated into sediments. The primary goal of this research was to determine how deeply oil from the 2010 Deepwater Horizon spill has penetrated sediments along the Gulf Coast, and whether oil has quantifiably affected benthic ecosystems at these sites. Sediment cores were taken from three marsh environments at sites classified as unoiled, lightly oiled, and heavily oiled based on data from NOAA's Environmental Response Management Application (ERMA). These classifications have been verified by measurements of total polycyclic aromatic hydrocarbons ([TPAH] without perylene). Bioturbators, such as polychaetes and oligochaetes, constantly rework sediments as they burrow into them. In this way, bioturbators can play a role in the fate of organic contaminants, either by allowing for natural remediation of contaminants via enhanced microbial degradation, or by mixing oil from the surface deeper into the sediment column. The constant fallout radionuclide 7Be was measured to determine short-term sediment mixing depths. However, there was a conspicuous absence of 7Be at most sites. This could be due to sediment composition constraints on 7Be sorption (coarse-grained sediment, high organic matter contents), or rapid erosion of the marsh surface. Instead, minimum mixing depths were derived from 234Thxs profiles. Thorium-234 is a lithogenic isotope that has widely been used to trace particle mixing on short time scales near that of its mean life (36 days). Penetration depths of 234Thxs ranged between 0.25 and 4.5 cm. Sediment accumulation rates will be determined using 210Pb, with verification from an independent tracer, 137Cs, in selected cores. Preliminary results from 210Pb profiles reveal thorough, long-term (decadal) sediment mixing to at least 40 cm at all sites. Salt marsh sediments of Bay Jimmy, Louisiana were significantly impacted by the DWH oil spill, as indicated by TPAH concentrations up to 18,279 ppb. This is not only well above what is considered to be the upper limit background for this area (1,500 ppb), but also far exceeds the level at which adverse biological effects occur (Effects Range-Low = 4,022 ppb). In addition, benthic foraminifera responded to the heavy oiling at Bay Jimmy by decreases to both standing stock and depth of habitation relative to unoiled sites. Deformed specimens were also found at this site. These data clearly show that oil can be quickly incorporated into salt marsh sediments via mixing, with demonstrable impacts on indigenous benthos.
Seasonal habitat-use patterns of nekton in a tide-restricted and unrestricted New England salt marsh
Raposa, K.B.; Roman, C.T.
Many New England salt marshes remain tide-restricted or are undergoing tidal restoration. Hydrologic manipulation of salt marshes affects marsh biogeochemistry and vegetation patterns, but responses by fishes and decapod crustaceans (nekton) remain unclear, This study examines nekton habitat-use patterns in the tide-restricted Hatches Harbor salt marsh (Provincetown, Massachusetts) relative to a downstream, unrestricted marsh. Nekton assemblages were sampled in tidal creek, marsh pool, and salt marsh surface habitats. Pools and creeks were sampled every two weeks for one year to account for seasonal variability, and the marsh surface was sampled at two-week intervals in summer and fall. Density, richness, and community composition of nekton in creek and marsh surface habitats were similar between the unrestricted and restricted marsh, but use of pools differed drastically on the two sides of the tide-restricting dike. In 95% of the cases tested, restricted marsh habitats provided equal or greater habitat value for nekton than the same habitat in the unrestricted marsh (based on density), suggesting that the restricted marsh did not provide a degraded habitat for most species. For some species, the restricted marsh provided nursery, breeding, and overwintering habitat during different seasons, and tidal restoration of this salt marsh must be approached with care to prevent losses of these valuable marsh functions.
High marsh habitats in New England exhibit conspicuous zonation of vas- cular plants. Spartina patens and Juncus gerardi dominate the seaward and terrestrial borders of the high marsh, respectively, whereas Dist~chlis spicata is common in disturbed habitats. In this paper I examine the role of interspecific interactions among these marsh perennials in maintaining marsh plant zonation. Removal and transplant experiments
Relationships between sedimentation, plant species, and the proximity to tidal channels in coastal salt marshes
NASA Astrophysics Data System (ADS)
Mudd, S. M.; Howell, S. M.; Furbish, D. J.; Morris, J. T.
Deposition of sediment on vegetated salt marshes enables these marshes to maintain their elevation relative to rising sea level. It has been found that deposition rates of suspended sediment on vegetated salt marshes are highest near tidal channels. This is due to the reduction in turbulence as flows from the tidal channel encounter the stems of the macrophytes that live on the marsh. Despite the presence of levees along some tidal channels, many marsh surfaces paradoxically slope gently upward away from tidal creeks, despite the reduction of deposition of suspended sediment distal from the salt marsh creek. We explore the effect of different marsh species on deposition rates in order to explain this apparent paradox. In the Beaufort Inlet, North Carolina, Spartina alterniflora tends to grow at low elevations near tidal channels, whereas Juncus roemerianus occupies higher elevations distal from the tidal channels. Juncus roemerianus tends to have greater biomass and stem density; this causes it to be more effective at trapping suspended sediment, and may lead Juncus roemerianus to have a higher rate of organogenic sedimentation compared to Spartina alterniflora. We explore how these two effects may allow the portion of the marsh populated by Juncus roemerianus to remain at a higher elevation than the portion of the marsh occupied by Spartina alterniflora, despite the greater rate of deposition due to the settling of suspended sediment in portions of the marsh near the tidal channels.
Silica uptake by Spartina-evidence of multiple modes of accumulation from salt marshes around the world.
Carey, Joanna C; Fulweiler, Robinson W
Silicon (Si) plays a critical role in plant functional ecology, protecting plants from multiple environmental stressors. While all terrestrial plants contain some Si, wetland grasses are frequently found to have the highest concentrations, although the mechanisms driving Si accumulation in wetland grasses remain in large part uncertain. For example, active Si accumulation is often assumed to be responsible for elevated Si concentrations found in wetland grasses. However, life stage and differences in Si availability in the surrounding environment also appear to be important variables controlling the Si concentrations of wetland grasses. Here we used original data from five North American salt marshes, as well as all known published literature values, to examine the primary drivers of Si accumulation in Spartina, a genus of prolific salt marsh grasses found worldwide. We found evidence of multiple modes of Si accumulation in Spartina, with passive accumulation observed in non-degraded marshes where Spartina was native, while rejective accumulation was found in regions where Spartina was invasive. Evidence of active accumulation was found in only one marsh where Spartina was native, but was also subjected to nutrient over-enrichment. We developed a conceptual model which hypothesizes that the mode of Si uptake by Spartina is dependent on local environmental factors and genetic origin, supporting the idea that plant species should be placed along a spectrum of Si accumulation. We hypothesize that Spartina exhibits previously unrecognized phenotypic plasticity with regard to Si accumulation, allowing these plants to respond to changes in marsh condition. These results provide new insight regarding how salt marsh ecosystems regulate Si exchange at the land-sea interface. PMID:24904599
Silica uptake by SpartinaŚevidence of multiple modes of accumulation from salt marshes around the world
Carey, Joanna C.; Fulweiler, Robinson W.
Silicon (Si) plays a critical role in plant functional ecology, protecting plants from multiple environmental stressors. While all terrestrial plants contain some Si, wetland grasses are frequently found to have the highest concentrations, although the mechanisms driving Si accumulation in wetland grasses remain in large part uncertain. For example, active Si accumulation is often assumed to be responsible for elevated Si concentrations found in wetland grasses. However, life stage and differences in Si availability in the surrounding environment also appear to be important variables controlling the Si concentrations of wetland grasses. Here we used original data from five North American salt marshes, as well as all known published literature values, to examine the primary drivers of Si accumulation in Spartina, a genus of prolific salt marsh grasses found worldwide. We found evidence of multiple modes of Si accumulation in Spartina, with passive accumulation observed in non-degraded marshes where Spartina was native, while rejective accumulation was found in regions where Spartina was invasive. Evidence of active accumulation was found in only one marsh where Spartina was native, but was also subjected to nutrient over-enrichment. We developed a conceptual model which hypothesizes that the mode of Si uptake by Spartina is dependent on local environmental factors and genetic origin, supporting the idea that plant species should be placed along a spectrum of Si accumulation. We hypothesize that Spartina exhibits previously unrecognized phenotypic plasticity with regard to Si accumulation, allowing these plants to respond to changes in marsh condition. These results provide new insight regarding how salt marsh ecosystems regulate Si exchange at the land-sea interface. PMID:24904599
Impact of an invasive plant ( Elymus athericus) on the conservation value of tidal salt marshes in western France and implications for management: Responses of spider populations
Julien Pķtillon; Frķdķric Ysnel; Alain Canard; Jean-Claude Lefeuvre
As a result of Elymus athericus (Poaceae) invasion in the last 10 years, a major change in vegetation cover has occurred in salt marshes of the Mont Saint-Michel bay (France). Such invasions are known to modify biodiversity and consequently ecosystem proprieties and functions as well as the conservation value of invaded areas. In this study, we especially focus (1) on
Lignocellulose-responsive bacteria in a southern California salt marsh identified by stable isotope probing
Darjany, Lindsay E.; Whitcraft, Christine R.; Dillon, Jesse G.
Carbon cycling by microbes has been recognized as the main mechanism of organic matter decomposition and export in coastal wetlands, yet very little is known about the functional diversity of specific groups of decomposers (e.g., bacteria) in salt marsh benthic trophic structure. Indeed, salt marsh sediment bacteria remain largely in a black box in terms of their diversity and functional roles within salt marsh benthic food web pathways. We used DNA stable isotope probing (SIP) utilizing 13C-labeled lignocellulose as a proxy to evaluate the fate of macrophyte-derived carbon in benthic salt marsh bacterial communities. Overall, 146 bacterial species were detected using SIP, of which only 12 lineages were shared between enriched and non-enriched communities. Abundant groups from the 13C-labeled community included Desulfosarcina, Spirochaeta, and Kangiella. This study is the first to use heavy-labeled lignocellulose to identify bacteria responsible for macrophyte carbon utilization in salt marsh sediments and will allow future studies to target specific lineages to elucidate their role in salt marsh carbon cycling and ultimately aid our understanding of the potential of salt marshes to store carbon. PMID:24917856
Acetate concentrations and oxidation in salt marsh sediments
NASA Technical Reports Server (NTRS)
Acetate concentrations and rates of acetate oxidation and sulfate reduction were measured in S. alterniflora sediments in New Hampshire and Massachusetts. Pore water extracted from cores by squeezing or centrifugation contained in greater than 0.1 mM acetate and, in some instances, greater than 1.0 mM. Pore water sampled nondestructively contained much less acetate, often less than 0.01 mM. Acetate was associated with roots, and concentrations varied with changes in plant physiology. Acetate turnover was very low whether whole core or slurry incubations were used. Radiotracers injected directly into soils yielded rates of sulfate reduction and acetate oxidation not significantly different from core incubation techniques. Regardless of incubation method, acetate oxidation did not account for a substantial percentage of sulfate reduction. These results differ markedly from data for unvegetated coastal sediments where acetate levels are low, oxidation rate constants are high, and acetate oxication rates greatly exceed rates of sulfate reduction. The discrepancy between rates of acetate oxidation and sulfate reduction in these marsh soils may be due either to the utilization of substrates other than acetate by sulfate reducers or artifacts associated with measurements of organic utilization by rhizosphere bacteria. Care must be taken when interpreting data from salt marsh sediments since the release of material from roots during coring may affect the concentrations of certain compounds as well as influencing results obtained when sediment incubations are employed.
Ecosystem Resilience of Coastal Marshes Following a Massive Oiling Event
NASA Astrophysics Data System (ADS)
Kolker, A. S.; Ameen, A. D.; Bianchi, T. S.; Cook, R. L.; Green, N.; Kolic, P.; Zhang, Y.
The Deepwater Horizon spill released an estimated 6.7 x 105 m3 of crude oil into the marine environment, leading to widespread fears of an environmental catastrophe. A considerable fraction found its way into Barataria Bay, one of the largest and most productive of the coastal bays in the Mississippi River delta. Beginning in May 2010, crude oil was transported to the northerly edge of the bay under the influence of southerly winds, where it was trapped by the fringing 5 - 20 m of Spartina alterniflora marsh. This heavy oiling led to the widespread mortality of marsh plants along this band of heavy oiling. However, on July 17, 2010 new shoots, often ~10 cm high, were observed in the die-off areas. Subsequently, re-growth was further quantified with digital photogrammetry. This re-growth suggests that the widespread oiling led to stem mortality, not root mortality. These findings have important implications for our understanding of ecosystem resilience, and for the impact of this massive oil spill on the erosion of coastal wetlands.
Factors influencing algal biomass in hydrologically dynamic salt ponds in a subtropical salt marsh
Miller, Carrie J.
Subtropical Salt Marsh. (May 2007) Carrie J. Miller, B.S., Millersville University Co-Chairs of Advisory Committee: Dr. Daniel Roelke Dr. Stephen Davis The interface between land and water is often a dynamic zone that responds to relatively...????????????????. 13 4 Hydrologic timeline (bay water level and local precipitation) for Guadalupe estuary, February 2005 through May 2006?????.. 17 5 Tidal creek salinity (A) and average salinity by site (B)...????. 18 6 Water column algal...
Tagus estuary and Ria de Aveiro salt marsh dynamics and the impact of sea level rise
NASA Astrophysics Data System (ADS)
Valentim, J. M.; Vaz, N.; Silva, H.; Duarte, B.; Cańador, I.; Dias, J. M.
Different characteristics of Spartina maritima found in two distinct salt marshes located in different estuaries were analysed through interpretation of their local hydrodynamic patterns, as well as the impact of sea level rise on physical processes and consequently on plant dynamics and salt marshes stability. These salt marshes are situated in two of the most important Portuguese coastal systems, Tagus estuary (Rosßrio salt marsh) and Ria de Aveiro lagoon (Barra salt marsh), which are dominated by physical processes that induce strong tidal currents. They were monitored during one year and plant and sediment samples of S. maritima were collected quarterly in order to determine the vegetation coverage, above and belowground biomass, organic matter and sediment moisture. Residual circulation, tidal asymmetry and tidal dissipation were determined from numerical modelling results of the MOHID 2D model that was applied to each coastal system, considering the actual sea level and a sea level rise (SLR) scenario. Results suggest that the different characteristics found for Spartina maritima in the Rosßrio and the Barra salt marshes may be related with the diverse hydrodynamic conditions identified for each salt marsh. Consequently, the exploration of SLR scenario predictions indicates how these salt marshes could evolve in the future, showing that the important changes in these hydrodynamic parameters under climate change context might induce significant modifications in the salt marshes dynamics and stability. SLR scenario could lead to changes in nutrients and sediments patterns around the salt marshes and thus vegetation coverage percentage would be affected. Additionally, as a consequence of flood duration increase, sediment moisture will increase causing a stress condition to plants. Hence, the ratio below/aboveground biomass might increase, becoming critical to plants survival under conditions of accelerated sea level rise. Accordingly, both SLR and expected changes in vegetation coverage percentage in controlling salt marshes evolution have important implications in their stability and consequently in coastal management. These conditions are unlikely to be unique to these salt marshes and it is suggested that similar analyses are replicated for other tidally dominated systems to improve understanding and characterization of their dynamics and stability under climate change context.
Latitudinal variation in herbivore pressure in Atlantic Coast salt marshes.
Pennings, Steven C; Ho, Chuan-Kai; Salgado, Cristiano S; Wieski, Kazimierz; Davķ, Nilam; Kunza, Amy E; Wason, Elizabeth L
Despite long-standing interest in latitudinal variation in ecological patterns and processes, there is to date weak and conflicting evidence that herbivore pressure varies with latitude. We used three approaches to examine latitudinal variation in herbivore pressure in Atlantic Coast salt marshes, focusing on five abundant plant taxa: the grass Spartina alterniflora, the congeneric rushes Juncus gerardii and J. roemerianus, the forb Solidago sempervirens, and the shrubs Iva frutescens and Baccharis halimifolia. Herbivore counts indicated that chewing and gall-making herbivores were typically > or = 10 times more abundant at low-latitude sites than at high-latitude sites, but sucking herbivores did not show a clear pattern. For two herbivore taxa (snails and tettigoniid grasshoppers), correctly interpreting latitudinal patterns required an understanding of the feeding ecology of the species, because the species common at high latitudes did not feed heavily on plant leaves whereas the related species common at low latitudes did. Damage to plants from chewing herbivores was 2-10 times greater at low-latitude sites than at high-latitude sites. Damage to transplanted "phytometer" plants was 100 times greater for plants transplanted to low- than to high-latitude sites, and two to three times greater for plants originating from high- vs. low-latitude sites. Taken together, these results provide compelling evidence that pressure from chewing and gall-making herbivores is greater at low vs. high latitudes in Atlantic Coast salt marshes. Sucking herbivores do not show this pattern and deserve greater study. Selective pressure due to greater herbivore damage at low latitudes is likely to partially explain documented patterns of low plant palatability to chewing herbivores and greater plant defenses at low latitudes, but other factors may also play a role in mediating these geographic patterns. PMID:19294924
Evidence for iron-sulfate coupling in salt marsh sediments
NASA Astrophysics Data System (ADS)
Mills, Jennifer; Antler, Gilad; Turchyn, Alexandra
Organic carbon burial in shallow marine sediments represents an important net sink in the global carbon cycle. Microbially mediated oxidation of organic matter in oxic, suboxic, and anoxic sediments however, prevents the ultimate burial of organic carbon and its removal from the surface of the planet. Although the subsurface transformations of organic carbon have been studied extensively, an enigmatic question remains: when organic matter is deposited, what determines whether it will be buried, reoxidized, or undergo methanogenesis? One hypothesis is that the sulfur cycle, due to the abundance of sulfate in many surface environments, dominates the subsurface oxidation or other fate of organic carbon. However, it has also been suggested that iron may in turn play a key role in determining the behavior of the sulfur cycle. To better understand the controls on these processes, we are using stable isotope and geochemical techniques to explore the microbially mediated oxidation of organic carbon in salt marsh sediments in North Norfolk, UK. In these sediments there is a high supply of organic carbon, iron, and sulfate (from diurnal tidal cycles). Thus these environments may provide insight into the nature of interactions between the carbon, iron, and sulfur cycles. A series of sampling missions was undertaken in the autumn and winter of 2013-2014. In subsurface fluid samples we observe very high ferrous iron concentrations (>1mM), indicative of extended regions of iron reduction (to over 30cm depth). Within these zones of iron reduction we would predict no sulfate reduction, and as expected ?34Ssulfate remains unchanged with depth. However, ?18Osulfate exhibits significant enrichments of up to 5 permil. This decoupling in the sulfur and oxygen isotopes of sulfate is suggestive of a sulfate recycling process in which sulfate is reduced to an intermediate sulfur species and subsequently reoxidized to sulfate. Taken together, these data suggest that microbial assemblages in these salt marsh sediments facilitate a cryptic cycling of sulfur, potentially mediated by iron species in the zone of iron reduction.
Using the radium quartet for evaluating groundwater input and water exchange in salt marshes
W Rama; Willard S. Moore
The fluxes of 226Ra (half-life = 1600 years) and 228Ra (half-life = 5.7 years) from the North Inlet salt marsh to the sea are much larger than can be supported by decay of their Th parents in the surface marsh sediments. These fluxes are sustained almost entirely by groundwater flow through the marsh. An average groundwater flow of approximately 10
Tidal Flushing Restores the Physiological Condition of Fish Residing in Degraded Salt Marshes
Dibble, Kimberly L.; Meyerson, Laura A.
Roads, bridges, and dikes constructed across salt marshes can restrict tidal flow, degrade habitat quality for nekton, and facilitate invasion by non-native plants including Phragmites australis. Introduced P. australis contributes to marsh accretion and eliminates marsh surface pools thereby adversely affecting fish by reducing access to intertidal habitats essential for feeding, reproduction, and refuge. Our study assessed the condition of resident fish populations (Fundulus heteroclitus) at four tidally restricted and four tidally restored marshes in New England invaded by P. australis relative to adjacent reference salt marshes. We used physiological and morphological indicators of fish condition, including proximate body composition (% lipid, % lean dry, % water), recent daily growth rate, age class distributions, parasite prevalence, female gravidity status, length-weight regressions, and a common morphological indicator (FultonÆs K) to assess impacts to fish health. We detected a significant increase in the quantity of parasites infecting fish in tidally restricted marshes but not in those where tidal flow was restored to reduce P. australis cover. Using fish length as a covariate, we found that unparasitized, non-gravid F. heteroclitus in tidally restricted marshes had significantly reduced lipid reserves and increased lean dry (structural) mass relative to fish residing in reference marshes. Fish in tidally restored marshes were equivalent across all metrics relative to those in reference marshes indicating that habitat quality was restored via increased tidal flushing. Reference marshes adjacent to tidally restored sites contained the highest abundance of young fish (ages 0¢1) while tidally restricted marshes contained the lowest. Results indicate that F. heteroclitus residing in physically and hydrologically altered marshes are at a disadvantage relative to fish in reference marshes but the effects can be reversed through ecological restoration. PMID:23029423
Tidal flushing restores the physiological condition of fish residing in degraded salt marshes.
Dibble, Kimberly L; Meyerson, Laura A
Roads, bridges, and dikes constructed across salt marshes can restrict tidal flow, degrade habitat quality for nekton, and facilitate invasion by non-native plants including Phragmites australis. Introduced P. australis contributes to marsh accretion and eliminates marsh surface pools thereby adversely affecting fish by reducing access to intertidal habitats essential for feeding, reproduction, and refuge. Our study assessed the condition of resident fish populations (Fundulus heteroclitus) at four tidally restricted and four tidally restored marshes in New England invaded by P. australis relative to adjacent reference salt marshes. We used physiological and morphological indicators of fish condition, including proximate body composition (% lipid, % lean dry, % water), recent daily growth rate, age class distributions, parasite prevalence, female gravidity status, length-weight regressions, and a common morphological indicator (Fulton's K) to assess impacts to fish health. We detected a significant increase in the quantity of parasites infecting fish in tidally restricted marshes but not in those where tidal flow was restored to reduce P. australis cover. Using fish length as a covariate, we found that unparasitized, non-gravid F. heteroclitus in tidally restricted marshes had significantly reduced lipid reserves and increased lean dry (structural) mass relative to fish residing in reference marshes. Fish in tidally restored marshes were equivalent across all metrics relative to those in reference marshes indicating that habitat quality was restored via increased tidal flushing. Reference marshes adjacent to tidally restored sites contained the highest abundance of young fish (ages 0-1) while tidally restricted marshes contained the lowest. Results indicate that F. heteroclitus residing in physically and hydrologically altered marshes are at a disadvantage relative to fish in reference marshes but the effects can be reversed through ecological restoration. PMID:23029423
N2O Flux from Salt Marshes in Estuaries along the Gulf of St. Lawrence
NASA Astrophysics Data System (ADS)
Roughan, B.; Kellman, L. M.; Chmura, G. L.
Wetlands are widely noted as filters for nutrient-laden waters. However, soils in tidal salt marshes emit nitrous oxide (N2O) when experimentally fertilized, which suggests that improved water quality comes at the expense of increased atmospheric concentrations of this potent greenhouse gas. Here we report on N2O emissions from four salt marshes located in estuaries along the Gulf of St. Lawrence. Our control site is located in a National Park on the coast of New Brunswick, which is in a region of low population density and limited agriculture, whereas the other estuaries have watersheds characterized by intensive agriculture activities on Prince Edward Island (PEI). N2O gas was collected during low tide, using opaque, static-chambers (17 L, 25 cm diameter) placed over marsh vegetation in the Spartina patens-dominated high marsh, which is typical of salt marshes along the northwest Atlantic coast, from New York north to Atlantic Canada. Preliminary analysis of gas samples collected in June revealed that the average N2O flux from the marshes located in agriculturally intensive watersheds (6.17 ū1.82 ?g N2O m-2 hr-1) was significantly higher than the flux from the control marsh, which was negligible (-2.63 ū2.22 ?g N2O m-2 hr-1). Assuming this elevated N2O flux is typical of the growing season (May-October), these marshes emit an average of 27 ū8 mg N2O m-2 yr-1 (or 8 g CO2e m-2 yr-1), 8.4% of the annual soil C accumulation rate reported for PEI. These results suggest that unintentional N fertilization of salt marshes located in agriculturally dominated watersheds may be fueling significant anthropogenic greenhouse gas emissions in some marshes. Further work during the 2013 growing season will provide insight into the environmental variables that affect the flux of N2O from these tidal salt marshes.
Salt Marsh Sediment Biogeochemical Response to the Deep Water Horizon BP Oil Spill (Skiff Island, LA, and Cat Island, Marsh Point, and Salt Pan Island, MS)
NASA Astrophysics Data System (ADS)
Guthrie, C. L.; McNeal, K. S.; Mishra, D. R.; Blakeney, G. A.
The large scale impact of the Deep Water Horizon BP Oil Spill on biological communities can be better predicted by developing an understanding of how carbon loading from the spill is affecting the microbial and biological communities of salt marshes along the Mississippi and Louisiana Gulf Coast. Sediment biogeochemical processes that degrade enriched carbon pools through sulfate reduction are primarily responsible for the biological breakdown of spilled hydrocarbons (Shin et al., 2000). Determination of sulfide concentration in contaminated areas, therefore, allows for an assessment of the oil spill impact on salt marsh at Skiff Island, LA, and Marsh Point, Cat Island, and Salt Pan Island, MS. As a result of carbon loading, porewater hydrogen sulfide (H2S) concentrations are expected to show an increase in the largely anoxic wetland sediment, making the sediment more toxic and inhospitable to marsh vegetation (Alber et al., 2008). High sulfide levels due to carbon loading in hydrocarbon contaminated salt marshes cause microbial activity to increase at the plant rhizospere, leading to plant browning and die back (Eldridge and Morse 2000). Preliminary analysis of the Marsh Point study area was conducted in Fall 2010. Sediment cores indicated that sulfate reducing bacteria are significantly more active in contaminated sediments, producing sulfide concentrations 20x higher than in non-contaminated sediments. The difference in the sediment biogeochemistry between the contaminated site and non-contaminated site at Marsh Point, MS indicated that the effects of hydrocarbon contamination on sulfur cycling in salt marshes should be more spatially explored. In Fall 2011, the study was expanded to include Skiff Island, LA, and Cat Island, and Salt Pan Island, MS in addition to Marsh Point, MS. Sediment electrode profiles (H2S, O2, pH, and Eh), degree of hydrocarbon contamination (GC), grain size analysis, microbial community substrate level carbon utilization profiles, and total organic carbon results will be presented on these four locations in order to explore the potential sedimentary geochemical processes impacting salt marsh dieback, which may be enhanced as a result of the Deep Water Horizon BP Oil Spill.
Marine fungal diversity: a comparison of natural and created salt marshes of the north-central Gulf of Mexico.
Walker, Allison K; Campbell, Jinx
Marine fungal communities of created salt marshes of differing ages were compared with those of two reference natural salt marshes. Marine fungi occurring on the lower 30 cm of salt marsh plants Spartina alterniflora and Juncus roemerianus were inventoried with morphological and molecular methods (ITS T-RFLP analysis) to determine fungal species richness, relative frequency of occurrence and ascomata density. The resulting profiles revealed similar fungal communities in natural salt marshes and created salt marshes 3 y old and older with a 1.5 y old created marsh showing less fungal colonization. A 26 y old created salt marsh consistently exhibited the highest fungal species richness. Ascomata density of the dominant fungal species on each host was significantly higher in natural marshes than in created marshes at all three sampling dates. This study indicates marine fungal saprotroph communities are present in these manmade coastal salt marshes as early as 1 y after marsh creation. The lower regions of both plant hosts were dominated by a small number of marine ascomycete species consistent with those species previously reported from salt marshes of the East Coast of USA. PMID:20524584
Sulfate reduction in a New England salt marsh
Sulfate reduction rates were measured for 2 years in the peat of a salt mars by a radiotracer technique. Rates are high throughout the peat, from the surface to more than 20 cm deep. The integrated annual rate is about 75 mol SOŌ\\/sup 2 -\\/.mŌü╗┬▓.yrŌü╗┬╣, the highest yet reported for any natural ecosystem. Sulfate reduction accounts for the consumption of
Effects of Tide Stage on the Use of Salt Marshes by Wading Birds in Rhode Island
To determine how tide stage affects wading bird abundance, behavior, and foraging in three Narragansett Bay salt marshes (RI), we conducted surveys at 10-min intervals?across the full tidal range?during six days at each marsh in July/September of 2006. The wading bird community ...
Biostimulation For The Treatment Of An Oil-Contaminated Coastal Salt Marsh
A field study was conducted on a coastal salt marsh in Nova Scotia, Canada, during the summer of 2000. The objective of the study was to assess the effectiveness of biostimulation in restoring an oil-contaminated coastal marsh dominated by Spartina alterniflora under north...
Nitrogen enrichment is hypothesized to cause competitive displacement of dominant plants in New England salt marshes. In this Narragansett Bay, RI, field survey, we examined the vascular plant species richness and the extent, density, and height of Spartina species in ten marshe...
Northeastern Salt Marshes: Elevation Capital and Resilience to Sea Level Rise
Stable tidal salt marshes exist at an elevation that is supra-optimal relative to peak biomass production, which for Spartina alterniflora, and other marsh macrophytes, follows a parabolic distribution as a function of elevation, as a surrogate for inundation frequency. In order...
Modification of sediments and macrofauna by an invasive marsh plant
T. S. Talley; L. A. Levin
Invasive grasses have recently altered salt marsh ecosystems throughout the northern hemisphere. On the eastern seaboard of the USA, Phragmites australis has invaded both brackish and salt marsh habitats. Phragmites australis influence on sediments and fauna was investigated along a salinity and invasion-age gradient in marshes of the lower Connecticut River estuary. Typical salinities were about 19-24 ppt in Site
Salt marshes. (Latest citations from Oceanic abstracts). Published Search
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The bibliography contains citations concerning the environmental protection of coastal marshes. The citations explore the fauna and flora of the marshes, geological and ecological processes, and the effects of marine pollution. Seasonal and environmental variations, the effects of erosion, and stabilization techniques of marshes are also considered. (Contains 250 citations and includes a subject term index and title list.)
Native plant restoration combats environmental change: development of carbon and nitrogen sequestration capacity using small cordgrass in European salt marshes.
Curado, Guillermo; Rubio-Casal, Alfredo E; Figueroa, Enrique; Grewell, Brenda J; Castillo, Jes·s M
Restoration of salt marshes is critical in the context of climate change and eutrophication of coastal waters because their vegetation and sediments may act as carbon and nitrogen sinks. Our primary objectives were to quantify carbon (C) and nitrogen (N) stocks and sequestration rates in restored marshes dominated by Spartina maritima to provide support for restoration and management strategies that may offset negative aspects of eutrophication and climate change in estuarine ecosystems. Sediment C content was between ca. 13ĀmgĀCĀg(-1)and sediment N content was ca. 1.8ĀmgĀNĀg(-1). The highest C content for S. maritima was recorded in leaves and stems (ca. 420ĀmgĀCĀg(-1)) and the lowest in roots (361?▒?4ĀmgĀCĀg(-1)). S. maritima also concentrated more N in its leaves (31?▒?1ĀmgĀNĀg(-1)) than in other organs. C stock in the restored marshes was 29.6ĀtĀCĀha(-1); ca. 16Ā% was stored in S. maritima tissues. N stock was 3.6ĀtĀNĀha(-1), with 8.3Ā% stored in S. maritima. Our results showed that the S. maritima restored marshes, 2.5Āyears after planting, were sequestering atmospheric C and, therefore, provide some mitigation for global warming. Stands are also capturing nitrogen and reducing eutrophication. The concentrations of C and N contents in sediments, and cordgrass relative cover of 62Ā%, and low below-ground biomass (BGB) suggest restored marshes can sequester more C and N. S. maritima plantations in low marshes replace bare sediments and invasive populations of exotic Spartina densiflora and increase the C and N sequestration capacity of the marsh by increasing biomass production and accumulation. PMID:23591677
The effect of cattle grazing on the abundance and distribution of selected macroinvertebrates in west Galveston Island salt marshes
Martin, Jennifer Lynn
The effect of cattle grazing on the abundance and distribution of vegetation, burrowing crabs (Uca rapax, Uca pugnax, and Sesarma cinereum), marsh periwinkles (Littoraria irrorata), horn snails (Cerithidea pliculosa), and salt marsh snails (Melampus...
Rhode Island Salt Marshes: Elevation Capital and Resilience to Sea Level Rise
Tidal salt marsh is especially sensitive to deterioration due to the effects of accelerated sea level rise when combined with other anthropogenically linked stressors, including crab herbivory, changes in tidal hydrology, nutrient loading, dam construction, changes in temperature...
Rapid shoreward encroachment of salt marsh cordgrass in response to accelerated
Bertness, Mark D.
gerardi) typically dominate higher elevations. Monitoring plant zonal boundaries in two New England salt gerardi) dominates higher marsh elevations (8). Lower species borders are con- trolled by physical stress
Utilization of salt marsh edge habitats by newly settled Sciaenids in a subtropical estuary
Geary, Bert Wilson
Postsettlement patterns of habitat use along salt marsh shorelines of West Galveston Bay, Texas were examined for the bay spawning spotted seatrout (Cynoscion nebulosus), inshore spawning red drum (Sciaenops ocellatus), and offshore spawning...
In the past century, loading of terrestrial inorganic nitrogen to coastal receiving waters has increased dramatically. Salt marshes, because of their location between upland regions and coastal waters and their recognized role as nutrient transformers, have the potential to ameli...
Factors Affecting Carbohydrate Production and Loss in Salt Marsh Sediments of Galveston Bay
Wilson, Carolyn E.
Benthic microalgae (BMA) living within the surface sediment of salt marshes are highly productive organisms that provide a significant proportion of organic carbon inputs into estuarine systems. BMA secrete extracellular carbohydrates in the form...
The ecology of regularly flooded salt marshes of New England: A community profile
Teal, J.M.
The current state-of-the-art in scientific knowledge about intertidal salt marshes is presented, but restricted to one habitat in New England, specifically Great Sippewissett at Falmouth, Massachusetts. (PSB)
Effects of Nutrient Additions on Three Coastal Salt Marsh Plants Found in Sunset Cove, Texas
Rulon, Leslie
tidal elevations. Snow and Vince (1984) studying four 7 Alaskan salt marsh species at the Susitna Flats (Puccinellia nutkaensis, Triglochin maritimum, Carex ramenskii, and Carex lyngbyei) also found that each species was able to inhabit all...
Laboratory salt-marsh environments were treated with malathion, an organophosphate insectide, and aerobic heterotrophic bacteria were monitored to determine changes in their microbial ecology. Several physiological activities were assayed in both treated and untreated controls; h...
Dependence of fishery species on salt marshes: The role of food and refuge
Donald F. Boesch; R. Eugene Turner
Salt marshes are widely believed to serve as nurseries for many fishes and crustaceans of fishery value as a result of the\\u000a high production of vascular plant detritus and the protection from predation offered by shallow, spatially complex habitats.\\u000a Comparisons of the yields of species which reside in salt marsh habitats during critical life history stages (such as penaeid\\u000a shrimp)
Impact of the invasive native species Elymus athericus on carbon pools in a salt marsh
Lo'c Valķry; Virginie Bouchard; Jean-Claude Lefeuvre
The spread of the invasive native clonal grass Elymus athericus is one of the most significant changes that have affected the plant communities of European salt marshes in the last decade.\\u000a The goal of this study was to investigate the rate of this invasion and its impact on C cycling in a non-grazed salt marsh\\u000a of the Mont Saint-Michel Bay
Secondary succession on a high salt marsh at different grazing intensities
H. Feddersen; R. Bockholt
Succession occurs on a large part of German salt marshes following abandonment or reduction of grazing. Its speed and effect\\u000a on the biodiversity of salt marshes has been discussed in the literature. Permanent plot studies show site-dependent differences\\u000a in successional outcome. If grazing is to be continued, there is uncertainty about the stocking rates that are optimal for\\u000a the conservation
Biotic interactions mediate the expansion of black mangrove (Avicennia germinans) into salt marshes under climate change.
Guo, Hongyu; Zhang, Yihui; Lan, Zhenjiang; Pennings, Steven C
Many species are expanding their distributions to higher latitudes due to global warming. Understanding the mechanisms underlying these distribution shifts is critical for better understanding the impacts of climate changes. The climate envelope approach is widely used to model and predict species distribution shifts with changing climates. Biotic interactions between species, however, may also influence species distributions, and a better understanding of biotic interactions could improve predictions based solely on climate envelope models. Along the northern Gulf of Mexico coast, USA, subtropical black mangrove (Avicennia germinans) at the northern limit of its distribution grows sympatrically with temperate salt marsh plants in Florida, Louisiana, and Texas. In recent decades, freeze-free winters have led to an expansion of black mangrove into salt marshes. We examined how biotic interactions between black mangrove and salt marsh vegetation along the Texas coast varied across (i) a latitudinal gradient (associated with a winter-temperature gradient); (ii) the elevational gradient within each marsh (which creates different marsh habitats); and (iii) different life history stages of black mangroves (seedlings vs. juvenile trees). Each of these variables affected the strength or nature of biotic interactions between black mangrove and salt marsh vegetation: (i) Salt marsh vegetation facilitated black mangrove seedlings at their high-latitude distribution limit, but inhibited black mangrove seedlings at lower latitudes; (ii) mangroves performed well at intermediate elevations, but grew and survived poorly in high- and low-marsh habitats; and (iii) the effect of salt marsh vegetation on black mangroves switched from negative to neutral as black mangroves grew from seedlings into juvenile trees. These results indicate that the expansion of black mangroves is mediated by complex biotic interactions. A better understanding of the impacts of climate change on ecological communities requires incorporating context-dependent biotic interactions into species range models. PMID:23580161
Flow, sedimentation, and biomass production on a vegetated salt marsh in South Carolina: toward a predictive model of marsh morphologic and ecologic evolution
NASA Astrophysics Data System (ADS)
Fagherazzi, S.; Mudd, S. M.; Morris, J. T.; Furbish, D. J.
A 1-D model for exploring the interaction between hydrodynamics, sedimentation, and plant community evolution on a salt marsh populated by Spartina alterniflora is developed. In the model tidally induced flows over marsh platforms are affected by S. alterniflora through drag forces. In general macrophyte characteristics are determined by a wide range of processes; here, based on field studies at North Inlet estuary, South Carolina, the biomass of the S. alterniflora on the marsh platform is simply related to their time of submergence under tidally induced flows. Additionally, field data collected at North Inlet are used to relate biomass to plant area per unit volume, stem diameter, and an empirical drag coefficient. Sedimentation is also related to biomass, through either organogenic deposition or trapping of suspended sediment particles. The morphologic evolution of simulated marshes is explored by varying the sedimentation process and the rate of sea level rise. Different sedimentation processes result in marshes with different morphologies. An organogenic marsh is predicted to evolve under a regime of steady sea level rise into a platform with a relatively flat surface, whereas a marsh developed primarily through a trapping mechanism is predicted to have a surface that slopes gently away from the salt marsh creek. As predicted by 0-D modeling studies, sea level rise may be accommodated up to a certain critical sea level rise rate, after which the salt marsh platform will drown. Marshes that accrete through sediment trapping adjust to changes in sea level more rapidly than marshes that accrete through organogenic deposition.
Salt marsh and seagrass communities of Bakkhali Estuary, Cox's Bazar, Bangladesh
NASA Astrophysics Data System (ADS)
Hena, M. K. Abu; Short, F. T.; Sharifuzzaman, S. M.; Hasan, M.; Rezowan, M.; Ali, M.
The species identification, distribution pattern, density and biomass of salt marsh and seagrass plants with some of the ecological parameters were studied in the Bakkhali river estuary, Cox's Bazar, Bangladesh during the first half of 2006. Two salt marsh species ( Spartina sp. and Imperata cylindrica) and one seagrass species ( Halophila beccarii) were identified during this investigation, providing the first reports of Spartina sp. and H. beccarii in coastal Bangladesh. Seagrass H. beccarii was found in an accreted area and co-existing with salt marsh, and scattered sparsely in the salt marsh habitat and macroalgae Ulva intestinalis. Flowering and fruiting were recorded from the seagrass H. beccarri during January and February. No flowers and fruits were observed for the salt marsh Spartina sp. during the study period. Results showed that the shoot density of Spartina ranged from 400 to 2875 shoots m -2 with the highest total biomass (165.80 g dry weight (DW) m -2) in March. Shoot density of H. beccarii ranged from 2716 to 14320 shoots m -2 in this estuarine coastal environment. The total biomass of seagrass was higher (17.56 g DW m -2) in March compared to the other months. The highest H. beccarii above ground (AG) biomass and below ground (BG) biomass were 9.59 g DW m -2 and 9.42 g DW m -2, respectively. These parameters are comparable with those generally observed for the salt marsh and seagrass species in the other places of the world.
Accumulation and transport of Cd, Cu, and Pb in an estuarine salt marsh surface microlayer
Lion, L.W.; Leckie, J.O.
Dissolved and particulate Cd, Cu, and Pb were measured in bulk solution and surface microlayer samples from an intertidal salt marsh in south San Francisco Bay. The phase distribution (dissolved vs. particulate) of metals was consistent with their calculated speciation in computer-simulated sea-salt matrices. Trace metal enrichment at the microlayer corresponded with physical events at the sample site. Advective exchange of Cd, Cu, and Pb between the estuary and marsh systems was dominated by transport of bulk suspended particulate metals, with an apparent net export from the marsh to the bay.
Restoring marsh elevation in a rapidly subsiding salt marsh by thin-layer deposition of dredged material
Ford, M.A.; Cahoon, D.R.; Lynch, J.C.
Thin-layer deposition of dredged material on coastal marsh by means of high-pressure spray dredging (Jet-Spray??2) technology has been proposed as a mechanism to minimize wetland impacts associated with traditional bucket dredging technologies and to restore soil elevations in deteriorated marshes of the Mississippi River delta. The impact of spray dredging on vegetated marsh and adjacent shallow-water habitat (formerly vegetated marsh that deteriorated to open water) was evaluated in a 0.5-ha Spartina alterniflora-dominated salt marsh in coastal Louisiana. The thickness of dredged sediment deposits was determined from artificial soil marker horizons and soil elevation change was determined from sedimentation-erosion tables (SET) established prior to spraying in both sprayed and reference marshes. The vertical accretion and elevation change measurements were made simultaneously to allow for calculation of shallow (~5 m depth) subsidence (accretion minus elevation change). Measurements made immediately following spraying in July 1996 revealed that stems of S. alterniflora were knocked down by the force of the spray and covered with 23 mm of dredged material. Stems of S. alterniflora soon recovered, and by July 1997 the percent cover of S. alterniflora had increased three-fold over pre-project conditions. Thus, the layer of dredged material was thin enough to allow for survival of the S. alterniflora plants, with no subsequent colonization by plant species typical of higher marsh zones. By February 1998, 62 mm of vertical accretion accumulated at this site, and little indication of disturbance was noted. Although not statistically significant, soil elevation change was greater than accretion on average at both the spray and reference marshes, suggesting that subsurface expansion caused by increased root biomass production and/or pore water storage influence elevation in this marsh region. In the adjacent shallow water pond, 129 mm of sediment was deposited in July 1996 as a result of spraying, and despite initial shallow subsidence and continual erosion through February 1998, water bottom elevation was raised sufficiently to allow S. alterniflora to invade via rhizome growth from the adjacent marsh. Hence, thin-layer deposition of dredged material at this site was effective at restoring and maintaining marsh elevation after 1.5 years. However, if the open water sediment deposits are not soon completely stabilized via further vegetative colonization, erosion may eventually lower elevations to the level where emergent vegetation cannot persist.
Evaluation of tidal marsh restoration: Comparison of selected macroinvertebrate populations on a restored impounded valley marsh and an unimpounded valley marsh within the same salt marsh system in Connecticut, USA
NASA Astrophysics Data System (ADS)
Peck, Myron A.; Fell, Paul E.; Allen, Elizabeth A.; Gieg, Jennifer A.; Guthke, Carl R.; Newkirk, Michael D.
Macroinvertebrates were examined on an impounded valley marsh in Stonington, Connecticut, that has changed from a Typha-dominated system to one with typical salt-marsh vegetation during 13 years following the reintroduction of tidal exchange. Animal populations on this restored impounded marsh were evaluated by comparing them with populations on a nearby unimpounded valley marsh of roughly the same size. Populations of the high marsh snail, Melampus bidentatus Say, were quantitatively sampled along transects that extended from the water-marsh edge to the upland; those of the ribbed mussel, Geukensia demissa Dillwyn, were sampled in low marsh areas on transects along the banks of creeks and mosquito ditches. The occurrence of other marsh invertebrates also was documented, but their abundance was not measured. The mean density of Melampus was 332▒39.6 SE/m2 on the restored impounded marsh and 712▒56.0 SE/m2 on the unimpounded marsh. However, since snails were larger on the restored impounded marsh, the difference in snail biomass was less pronounced than the difference in snail density. Mean Melampus biomass was 4.96▒0.52 SE g dry wt/m2 on the restored impounded marsh and 6.96▒0.52 SE g dry wt/m2 on the unimpounded marsh. On the two marshes, snail density and biomass varied in relation to plant cover and other factors. The density and biomass of Geukensia at the edge of the marsh were comparable on the restored impounded and unimpounded marshes. Mean mussel densities ranged from 80 to 240/m2 and mean mussel biomass varied from 24.8-64.8 g dry wt/m2 in different low marsh areas. In contrast, below the impoundment dike, mean Geukensia density was 1100▒96.4 SE/m2 and mean Geukensia biomass was 303.6▒33.28 SE g dry wt/m2. A consideration of all available evidence leads to the conclusion that the impounded marsh is in an advanced phase of restoration.
Herbivory affects salt marsh succession dynamics by suppressing the recovery of dominant species.
Daleo, Pedro; Alberti, Juan; Pascual, Jes·s; Canepuccia, Alejandro; Iribarne, Oscar
Disturbance can generate heterogeneous environments and profoundly influence plant diversity by creating patches at different successional stages. Herbivores, in turn, can govern plant succession dynamics by determining the rate of species replacement, ultimately affecting plant community structure. In a south-western Atlantic salt marsh, we experimentally evaluated the role of herbivory in the recovery following disturbance of the plant community and assessed whether herbivory affects the relative importance of sexual and clonal reproduction on these dynamics. Our results show that herbivory strongly affects salt marsh secondary succession by suppressing seedlings and limiting clonal colonization of the dominant marsh grass, allowing subordinate species to dominate disturbed patches. These results demonstrate that herbivores can have an important role in salt marsh community structure and function, and can be a key force during succession dynamics. PMID:24549938
Remote sensing of biomass and annual net aerial primary productivity of a salt marsh
NASA Technical Reports Server (NTRS)
Hardisky, M. A.; Klemas, V.; Daiber, F. C.; Roman, C. T.
Net aerial primary productivity is the rate of storage of organic matter in above-ground plant issues exceeding the respiratory use by the plants during the period of measurement. It is pointed out that this plant tissue represents the fixed carbon available for transfer to and consumption by the heterotrophic organisms in a salt marsh or the estuary. One method of estimating annual net aerial primary productivity (NAPP) required multiple harvesting of the marsh vegetation. A rapid nondestructive remote sensing technique for estimating biomass and NAPP would, therefore, be a significant asset. The present investigation was designed to employ simple regression models, equating spectral radiance indices with Spartina alterniflora biomass to nondestructively estimate salt marsh biomass. The results of the study showed that the considered approach can be successfully used to estimate salt marsh biomass.
Hydrodynamic modeling for river delta salt marshes using lidar topography
NASA Astrophysics Data System (ADS)
Hodges, Ben R.
Topographic data from lidar and multi-beam sonar create new challenges for hydrodynamic models of estuaries, tidelands, and river deltas. We now can readily obtain detailed elevation data on 1 m scales and finer, but solving hydrodynamics with model grid cells at these small scales remains computationally prohibitive (primarily because of the small time step required for small grid cells). Practical estuarine models for the next decade or so will likely have grid scales in the range of 5 to 15 m. So how should we handle known subgrid-scale features? Simply throwing out known data does not seem like a good idea, but there is no consensus on how best to incorporate knowledge of subgrid topography into either hydrodynamic or turbulence models. This presentation discusses both the theoretical foundations for modeling subgrid-scale features and the challenges in applying these ideas in the salt marshes of a river delta. The subgrid problem highlights some important areas for field and laboratory research to provide calibration parameters for new models that upscale the effects of known subgrid features.
Water, Salt, and Nutrient Balances in an Estuarine Salt Marsh (Murderkill River Estuary, Kent County, Delaware) Project Period: 1 June 2007 to 30 November 2008
Anthony Aufdenkampe
Objective: To determine whether salt marsh is a source or sink of nutrient species contributing to the oxygen demand of the Murderkill River Estuary (Kent County, Delaware) by measuring water, salt, and nutrient (N, P, C, Si) balances in and out of a constrained section of polyhaline salt-marsh. The results of this study will be used to verify and calibrate
Technology Transfer Automated Retrieval System (TEKTRAN)
In recent years, more residential homes have been built around the marsh areas located on the Intra-Coastal Waterway (ICW) and brought more complaints about marsh mosquitoes. Many homeowner associations have created policies and regulations that forbid the spraying of pesticides. The new challenge h...
Diagenesis of organic matter in georgia salt marshes
NASA Astrophysics Data System (ADS)
Fogel, Marilyn L.; Kent Sprague, E.; Gize, Andrew P.; Frey, Robert W.
Organic matter preserved in sediments of Georgia salt marshes derives from Spartina alterniflora and planktonic and bacterial substances. Sources and diagenesis of sedimentary organic material were studied by means of stable C and N isotopes and gas chromatography of pyrolysates from plants, suspended sediments, and a series of muds (modern to 1400 years old) from St Catherines Island, Georgia. Suspended particulate matter ( > 20 ?m) has isotopic compositions (? 13C = -18 to -22), which are composed of an average 34-42% plankton carbon and 58-65% higher plant detritus, as determined by isotopic mass balance of the system. The ? 13C of bulk sediments and humic acids (? 13C = -18 to -19) extracted from them remain relatively constant over time. The ? 13C of acid hydrolysates, however, changed from - 15ē in surface marsh sediment to a ? 13C of -19 from sediment sampled at a depth of 125 cm. Higher-plant normal-hydrocarbons are present in muds and in particulate matter from the water column, and ? 13C in lipids and gas chromatography of pyrolysates of samples reflect this addition. With increasing age, ? 15N of total sediments and acid hydrolysates increases, and the ratio of odd-to-even hydrocarbons in the pyrolysates decreases. Initially, low density material in sediments consists primarily of plant fragments. With time, this material is decayed and diluted by microbial material, changes that are reflected by more negative ? 13C of -15 to -17Ę5, as compared to ? 13C of -12 for moden Spartina, and the addition of n-alkanes in the range of C 13-19. The isotopic heterogeneity in surface sediments with carbon as an example, ranged from a ? 13C of -15 (plant fragments) to -22 (sediment following lipid, humic acid, and plant fragment extraction). Nowhere was the C isotopic composition of total Spartina expressed even though microscopic plant pieces, lignocellulose pyrolysis fragments, and n-alkanes from C 22-27 were detected in suspended particulate matter, total sediments, and humic acids.
Assessing the performance of salt marsh and mangrove foraminifera as sea-level indicators
NASA Astrophysics Data System (ADS)
Liu, S.; Horton, B. P.; Toscano, M. A.; Engelhart, S. E.; Hawkes, A.
Salt marsh foraminifera have proven to be an accurate sea-level indicator because their distributions on low-energy, organic coasts are vertically zoned with respect to the tidal frame and their tests are readily preserved in the sedimentary sequences. However, in contrast to salt marsh-based studies, there are fewer studies using mangrove foraminifera to reconstruct former sea level despite the importance of far field tropical localities for inferring the ice-equivalent component to relative sea-level change. This study compares the performance of salt marsh and mangrove foraminifera as sea-level indicators and attempts to reconstruct relative sea-level (RSL) change at decimeter scale using mangrove foraminifera. We chose one salt marsh site (St. Marys) and one mangrove site (Hobe Sound) along the Atlantic coast of Florida with similar climatic, biological, and geological conditions. At each site we collected modern (88 samples from 6 transects) and fossil (salt marsh and mangrove peat cores) material. We found differences between these environments with regards to the abundance, composition and diversity of the foraminiferal assemblages. The most abundant species in the salt marsh are Ammobaculites spp., Ammoastuta inepta, Haplophragmoides spp., and Trochammina inflata, while the dominant mangrove species are Arenoparrelle mexicana, Ammodiscoides spp., Glomospira spp., and Haplophragmoides spp. We quantified the optimum and tolerance of each foraminiferal species to elevations relative to tidal frame and subsequently developed salt marsh and mangrove transfer functions (TF). The TFs estimate vertical uncertainty of ~ ▒ 0.2 m, indicating that precise reconstructions of RSL are possible. The fossil mangrove core is dominated by species similar to the modern assemblages. We applied the mangrove-based TF and combined this with a preliminary chronology based on 210Pb and 14C dates to reconstruct RSL, which was validated against regional tide-gauge records, demonstrating its usefulness in assessing sea level changes in tropical to semi-tropical locations.
Assessing the sedimentation deficit problem in Louisiana's coastal salt marshes
The imbalance between relative sea-level rise and vertical marsh accretion is frequently cited as a major factor in the problem of wetland loss in coastal Louisiana. Relative sea-level rise rates are high, compared to the rest of the Gulf coast, owing to subsidence of Holocene Mississippi deltaic plain sediments, and although marsh accretion rates are also high, in comparison with
Salt marsh submarine groundwater discharge as traced by radium isotopes
Matthew A. Charette; Richard Splivallo; Craig Herbold; Marsha S. Bollinger; Willard S. Moore
Submarine groundwater discharge (SGD) generally occurs through permeable sediments where the hydraulic head of an aquifer is above sea level, and often includes a recirculated seawater component. In order to determine SGD to the Great Sippewissett Marsh, West Falmouth, MA, we measured the activities of four radium isotopes (226Ra, 228Ra, 223Ra, 224Ra) at the marsh inlet in July 1999 and
Latitudinal and climate-driven variation in the strength and nature of biological interactions in New England salt marshes
Mark D. Bertness; Patrick J. Ewanchuk
We examined the linkage between climate and interspecific plant interactions in New England salt marshes. Because harsh edaphic conditions in marshes can be ameliorated by neighboring plants, plant neighbors can have net competitive or facilitative interactions, depending on ambient physical stresses. In particular, high soil salinities, which are largely controlled by solar radiation and the evaporation of marsh porewater, can
Chapter 19 Using GIS to display complex soil salinity patterns in an inland salt marsh
Matthew Grunstra; O. W. Van Auken
Inland salt marshes are found near salt lakes and desert springs in areas of high evaporation and low precipitation. Spatial and seasonal fluctuations of the soil salinity levels are assumed to be associated with local climate. However, topography complicates the general soil salinity patterns attributed to climate. To better demonstrate and display these spatial and temporal relationships, soil salinity data
Environmental gradients, plant distribution, and species richness in arctic salt marsh near Prudhoe Bay, Alaska
Dale W. Funk; Lynn E. Noel; Adam H. Freedman
Spatial patterns of plant cover and species composition in arctic salt marsh and salt affected tundra near Prudhoe Bay, Alaska reflect gradients in elevation, soil conductivity, and soil concentrations of the ions prevalent in seawater. Soil conductivity and soil concentrations of Ca2+, Mg2+, Na+, K+, SO4= and Cl- were significantly related to site elevation, decreasing as elevation increased. Vascular plant
The importance of salt-marsh wetness for seed exploitation by dabbling ducks Anas sp
Ole R. Therkildsen; Thomas Bregnballe
The relationship between the inundation of a salt marsh in southeast Denmark not subject to lunar tides and the availability and predation of seeds of the annuals Salicornia spp. and Suada maritima by autumn staging dabbling ducks was studied by carrying out exclosure experiments over the course of 2Āyears. There was a marked difference in the wetness of the salt
Composition of Fish Communities in a European Macrotidal Salt Marsh (the Mont Saint-Michel Bay,
Boyer, Edmond
Composition of Fish Communities in a European Macrotidal Salt Marsh (the Mont Saint-Michel Bay At least 100 fish species are known to be present in the intertidal areas (estuaries, mudflats and salt, such as estuaries and lagoons, play a nursery role for many fish species. However, in Europe little attention has
Grazing rates of organic matter and living fungal biomass of decaying Spartina alterniflora by three species of salt-marsh invertebrates
M. A. Grańa; S. Y. Newell; R. T. Kneib
The pathway for the flow of salt-marsh grass production into marsh food-webs is still not well defined. We compared the abilities\\u000a of three marsh macroinvertebrates [salt marsh periwinkles, Littoraria irrorata (Say) (=Littorina irrorata), salt-marsh coffee-bean snails, Melampus bidentatus (Say); and a talitrid amphipod, Uhlorchestia spartinophila Bounsfield and Heard] to access standing-dead leaves of smooth cordgrass (Spartina alterniflora Loisel). The invertebrates
A survey of zinc, copper and cadmium concentrations in salt marsh plants along the Dutch coast.
Otte, M L; Bestebroer, S J; van der Linden, J M; Rozema, J; Broekman, R A
In autumn 1986, plants and soil were collected from the lower and the higher salt marsh zones of salt marshes along the Dutch coast. The main purpose was to get an overview of Zn, Cu and Cd concentrations in six dominant species of salt marsh plants. The roots and shoots of the plants were analysed for Zn, Cu and Cd. The highest heavy metal concentrations were found in plants collected from salt marshes near harbour areas and/or that are known to receive contaminated fluvial sediment. Dicotyledonous plant species tended to have similar heavy metal concentrations in roots and shoots, whereas in monocotyledonous species the concentrations in the roots were two to three times higher than in the shoots. Differences in accumulation in the roots between elements and between plant species were found. Cd was accumulated more than Zn or Cu. Triglochin maritima shows a low Cd uptake by roots, whereas Spartina anglica and Scirpus maritimus tend to accumulate it. The fraction of soil particles smaller than 63 microm, loss on ignition and Zn, Cu and Cd concentrations were determined in soil samples. The highest Zn, Cu and Cd concentrations in the soil were found at salt marshes in the Western Scheldt area and were nine, five and 20 times higher than background levels, respectively. PMID:15092100
Mobility of Pb in salt marshes recorded by total content and stable isotopic signature
Miguel Caetano; Nuno Fonseca; Rute Cesßrio Carlos Vale
Total lead and its stable isotopes were analysed in sediment cores, leaves, stem and roots of Sacorconia fruticosa and Spartina maritima sampled from Tagus (contaminated site) and Guadiana (low anthropogenic pressure) salt marshes. Lead concentration in vegetated sediments from the Tagus marsh largely exceeded the levels in non-vegetated sediments. Depth profiles of 206Pb\\/207Pb and 206Pb\\/208Pb showed a decrease towards the
Growth of the salt marsh periwinkle Littoraria irrorata on fungal and cordgrass diets
F. Bõrlocher; S. Y. Newell
The growth of the salt marsh periwinkleLittoraria irrorata (collected from Sapelo Island, Georgia in 1991, initial shell length 6.2 to 11.5 mm) on various diets was measured. Growth was highest on a diet of standing-dead leaves ofSpartina alterniflora. Periwinkles provided with marsh sediment, yellow-green, sterile, or bacteria-colonized leaves lost organic mass. Fungal-colonized leaves and pure mycelia of fungi common on
Primary production and macro-detritus dynamics in a European salt marsh: carbon and nitrogen budgets
Virginie Bouchard; Jean-Claude Lefeuvre
Primary production and the detritus pathway (i.e., detritus production, litter fall, export to coastal waters, and decomposition) were studied over a 1-year period in three salt marsh levels (low, middle and high marshes). Carbon and nitrogen content in biomass and macro-detritus were estimated at each step of the detrital pathway. Several lines of evidence suggested that low, middle and high
Aggregative responses of brent geese on salt marsh and their impact on plant community dynamics
J. Marcus Rowcliffe; Andrew R. Watkinson; William J. Sutherland
The aggregative responses and habitat preferences of a generalist herbivore, the dark-bellied brent goose Branta bernicla bernicla, feeding on salt marshes are examined in relation to vegetation community characteristics and the abundances of individual\\u000a plant species. In the autumn, feeding was strongly concentrated on the low marsh, which had the highest biomass of the preferred\\u000a food plant, Salicornia europaea. There
Crab: snail size-structured interactions and salt marsh predation gradients
Daniel E. Schindler; Brett M. Johnson; Neil A. MacKay; Nicolaas Bouwes; James F. Kitchell
We studied size-structured predator-prey interactions between blue crabs (Callinectes sapidus) and marsh periwinkles (Littoraria irrorata) with a combination of field studies, laboratory experiments and individual-based modeling. Size distributions of Littoraria differed among years at the same sites in a salt marsh and could largely be explained by dominance of strong cohorts in the population. At a given site, abundance increased
Anthropogenic modification of New England salt marsh landscapes
Bertness, Mark D.
and eutrophication. On the seaward border of these marshes, nitrogen eutrophication stimulated by local shoreline of the common reed, Phragmites, by means of nitrogen eutrophication caused by the removal of the woody
Cable bacteria associated with long-distance electron transport in New England salt marsh sediment.
Larsen, Steffen; Nielsen, Lars Peter; Schramm, Andreas
Filamentous Desulfobulbaceae have been proposed as 'cable bacteria', which electrically couple sulfide oxidation and oxygen reduction in marine sediment and thereby create a centimetre-deep suboxic zone. We incubated New England salt marsh sediment and found long-distance electron transport across 6?mm and 16S rRNA genes identical to those of previously observed cable bacteria in Aarhus Bay sediment incubations. Cable bacteria density in sediment cores was quantified by fluorescence in situ hybridization. In contrast to the coastal, subtidal sediments with short-termed blooms of cable bacteria based on rapidly depleted iron sulfide pools, the salt marsh cable community was based on ongoing sulfate reduction and therefore probably more persistent. Previously observed seasonal correlation between Desulfobulbaceae dominance and extensive reduced sulfur oxidation in salt marshes suggest that cable bacteria at times may have an important role in situ. PMID:25224178
Effects of several salt marsh plants on mouse spleen and thymus cell proliferation using mtt assay
NASA Astrophysics Data System (ADS)
Seo, Youngwan; Lee, Hee-Jung; Kim, You Ah; Youn, Hyun Joo; Lee, Burm-Jong
In the present study, we have tested the effects of 21 salt marsh plants on cell proliferation of mouse immune cells (spleen and thymus) using MTT assay in culture. The methanolic extracts of six salt marsh plants ( Rosa rugosa, Ixeris tamagawaensis, Artemisia capillaris, Tetragonia tetragonoides, Erigeron annus, and Glehnia littoralis) showed very powerful suppressive effects of mouse immune cell death and significant activities of cell proliferation in vitro. Especially, the methanolic extract of Rosa rugosa was found to have fifteen times compared to the control treatment, demonstrating that Rosa rugosa may have a potent stimulation effect on immune cell proliferation. These results suggest that several salt marsh plants including Rosa rugosa could be useful for further study as an immunomodulating agent.
Trace metal concentrations in Spartina densiflora and associated soil from a Patagonian salt marsh.
Idaszkin, Yanina L; Bouza, Pablo J; Marinho, Carmen H; Gil, M¾nica N
The objectives of this study were to (i) assess in situ trace metal concentrations in soil and in Spartina densiflora in a Patagonian salt marsh (Rawson, Chubut, Argentina) and (ii) investigate the relationship between trace metal concentrations in soils and in plants to improve our knowledge regarding the ability of S. densiflora to take up and accumulate trace metals from the soil within its native region. Our results indicate that the soil and S. densiflora exhibit low metal concentrations in the Rawson salt marsh. S. densiflora accumulates Zn in below- and above-ground plant structures and Cr in below-ground parts. These results suggest at the time of this study there is scarce human impact associated with metals in the Rawson salt marsh. PMID:25457812
Survival, growth and reproduction of the salt-marsh amphipod Uhlorchestia spartinophila reared on natural diets of senescent and dead Spartina alterniflora leaves
R. T. Kneib; S. Y. Newell; E. T. Hermeno
The talitrid amphipod Uhlorchestia spartinophila lives in close association with standing-dead leaves of the smooth cordgrass Spartina alterniflora Loisel in salt marshes along the Atlantic coast of North America. This study probed the strength of the trophic link between\\u000a the amphipod population and the decomposition process in this detrital-based ecosystem. We measured survival, growth and reproductive\\u000a output in groups of
Does livestock grazing affect sediment deposition and accretion rates in salt marshes?
NASA Astrophysics Data System (ADS)
Nolte, Stefanie; M³ller, Frauke; Schuerch, Mark; Wanner, Antonia; Esselink, Peter; Bakker, Jan P.; Jensen, Kai
Accretion rates, defined as the vertical growth of salt marshes measured in mm per year, may be influenced by grazing livestock in two ways: directly, by increasing soil compaction through trampling, and indirectly, by reducing aboveground biomass and thus decreasing sediment deposition rates measured in g/m▓ per year. Although accretion rates and the resulting surface elevation change largely determine the resilience of salt marshes to sea-level rise (SLR), the effect of livestock grazing on accretion rates has been little studied. Therefore, this study aimed to investigate the effect of livestock grazing on salt-marsh accretion rates. We hypothesise that accretion will be lower in grazed compared to ungrazed salt marshes. In four study sites along the mainland coast of the Wadden Sea (in the south-eastern North Sea), accretion rates, sediment deposition rates, and soil compaction of grazed and ungrazed marshes were analysed using the 137Cs radionuclide dating method. Accretion rates were on average 11.6 mm yr-1 during recent decades and thus higher than current and projected rates of SLR. Neither accretion nor sediment deposition rates were significantly different between grazing treatments. Meanwhile, soil compaction was clearly affected by grazing with significantly higher dry bulk density on grazed compared to ungrazed parts. Based on these results, we conclude that other factors influence whether grazing has an effect on accretion and sediment deposition rates and that the effect of grazing on marsh growth does not follow a direct causal chain. It may have a great importance when interacting with other biotic and abiotic processes on the marsh.
Critical bifurcation of shallow microtidal landforms in tidal flats and salt marshes.
Fagherazzi, Sergio; Carniello, Luca; D'Alpaos, Luigi; Defina, Andrea
Shallow tidal basins are characterized by extensive tidal flats and salt marshes that lie within specific ranges of elevation, whereas intermediate elevations are less frequent in intertidal landscapes. Here we show that this bimodal distribution of elevations stems from the characteristics of wave-induced sediment resuspension and, in particular, from the reduction of maximum wave height caused by dissipative processes in shallow waters. The conceptual model presented herein is applied to the Venice Lagoon, Italy, and demonstrates that areas at intermediate elevations are inherently unstable and tend to become either tidal flats or salt marshes. PMID:16707583
The sources of mosquito blood meals in the salt marsh of Brazoria County, Texas
Metz, Richard Henry
Member Member (Memb ~Au st ~6 ASSTBACT T?'. e Sources of' I'Iosquito Bl odI IiIeals in the Salt Marsh -? Brazoria County, Texas, (August 196)) Directed by". D , Darryl P. Sanders salt marsh area in Bra;, aria County, 'exss that is normally u ed...;! ACKNOW'~JLEDGi~IENTS The author ?ashes to express his appreciation to Dr. Darryl P. Sanders, his raa, jor advisor, for his assistance and encouraSement in the ozpletion of thjs research. Also of great help was Dr. C, D. Stee'" . ~. , Entczolo, ". y...
Acute salt marsh dieback in the Mississippi River deltaic plain: A drought-induced phenomenon?
McKee, K.L.; Mendelssohn, I.A.; Materne, M.D.
Aims Extensive dieback of salt marsh dominated by the perennial grass Spartina alterniflora occurred throughout the Mississippi River deltaic plain during 2000. More than 100,000 ha were affected, with 43,000 ha severely damaged. The aim of this work was to determine if sudden dieback could have been caused by a coincident drought and to assess the significance of this event with respect to long-term changes in coastal vegetation. Location Multiple dieback sites and reference sites were established along 150 km of shoreline in coastal Louisiana, USA. Methods Aerial and ground surveys were conducted from June 2000 to September 2001 to assess soil conditions and plant mortality and recovery. Results Dieback areas ranged in size from???300 m2-5 km2 in area with 50-100% mortality of plant shoots and rhizomes in affected zones. Co-occurring species such as Avicennia germinans (black mangrove) and Juncus roemerianus (needlegrass rush) were unaffected. Historical records indicate that precipitation, river discharge, and mean sea level were unusually low during the previous year. Although the cause of dieback is currently unknown, plant and soil characteristics were consistent with temporary soil desiccation that may have reduced water availability, increased soil salinity, and/or caused soil acidification (via pyrite oxidation) and increased uptake of toxic metals such as Fe or Al. Plant recovery 15 months after dieback was variable (0-58% live cover), but recovering plants were vigorous and indicated no longlasting effects of the dieback agent. Main conclusions These findings have relevance for global change models of coastal ecosystems that predict vegetation responses based primarily on long-term increases in sea level and submergence of marshes. Our results suggest that large-scale changes in coastal vegetation may occur over a relatively short time span through climatic extremes acting in concert with sea-level fluctuations and pre-existing soil conditions. ?? 2004 Blackwell Publishing Ltd.
Long-term salt marsh vertical accretion in a tidal bay with reduced sediment supply
NASA Astrophysics Data System (ADS)
Ma, Zhigang; Ysebaert, Tom; van der Wal, Daphne; de Jong, Dick J.; Li, Xiuzhen; Herman, Peter M. J.
Because of damming and intensive human activities, the sediment supply to many estuaries and deltas is dramatically decreasing. In the Oosterschelde (southwest Netherlands), a storm surge barrier (SSB) and two compartmentalization dams were built in the 1980s to protect the densely inhabited inland against flooding. After these constructions, the tidal range and mean high water level in the Oosterschelde decreased by about 12% and suspended sediment concentrations in the channels dropped by 52-70% compared to the pre-barrier conditions. The vertical accretion rates of the three largest salt marshes (Rattekaai, Sint Annaland and Slaak) in the Oosterschelde in response to this decreased sediment supply were investigated. There was a general accreting trend over the entire post-barrier period (1988-2011) in all three marshes. The predicted slowdown in accretion rates by De Jong et al. (1994) did not persist, although accretion rates were lower than in the pre-barrier period. More than 20 year observations from kaoline markers showed variation of accretion rates within and among marshes. Year-to-year variation in accretion rates was large, but only weakly (not significantly) related to the duration and frequency of marsh overflow and over-marsh extreme flooding events. However, storm events are hypothesized to be responsible for the observed trends, but our observations lack the temporal resolution to identify specific storm events. Salt marshes in the Oosterschelde are expected to survive under the present sea level rise rate and subsidence rate scenarios.
The Role of Phragmites australis in Mediating Inland Salt Marsh Migration in a Mid-Atlantic Estuary
Smith, Joseph A. M.
Many sea level rise adaptation plans emphasize the protection of adjacent uplands to allow for inland salt marsh migration, but little empirical information exists on this process. Using aerial photos from 1930 and 2006 of Delaware Estuary coastal habitats in New Jersey, I documented the rate of coastal forest retreat and the rate of inland salt marsh migration across 101.1 km of undeveloped salt marsh and forest ecotone. Over this time, the amount of forest edge at this ecotone nearly doubled. In addition, the average amount of forest retreat was 141.2 m while the amount of salt marsh inland migration was 41.9 m. Variation in forest retreat within the study area was influenced by variation in slope. The lag between the amount of forest retreat and salt marsh migration is accounted for by the presence of Phragmites australis which occupies the forest and salt marsh ecotone. Phragmites expands from this edge into forest dieback areas, and the ability of salt marsh to move inland and displace Phragmites is likely influenced by salinity at both an estuary-wide scale and at the scale of local subwatersheds. Inland movement of salt marsh is lowest at lower salinity areas further away from the mouth of the estuary and closer to local heads of tide. These results allow for better prediction of salt marsh migration in estuarine landscapes and provide guidance for adaptation planners seeking to prioritize those places with the highest likelihood of inland salt marsh migration in the near-term. PMID:23705031
Salt marsh-atmosphere exchange of energy, water vapor, and CO2: effects of transient flooding
NASA Astrophysics Data System (ADS)
Moffett, K. B.; Gorelick, S.
Short-duration floods help sustain many wetland systems, yet benchmarks of important wetland-atmosphere interactions are typically derived from non-flooded conditions. Exchanges of energy, water vapor, and CO2 between an intertidal salt marsh and the atmosphere were quantified by eddy covariance, micrometeorology, and other field methods. A flood tide lasting less than three hours completely suppressed marsh-atmosphere CO2 exchange. Compared to non-flooded conditions, the radiation budget and latent heat flux of the salt marsh were larger and the sensible and soil heat fluxes smaller during daytime high tides, with large energy flux into the surface water. Night-time high tides had less pronounced, opposite effects on net radiation, soil heat flux, and surface water energy storage. Longer floods correlated with larger exchange flux perturbation. A suite of seven exchange models was used to diagnose key mechanisms causing the observed changes: different canopy/soil/water resistance to vapor transport, changed Bowen ratio, altered marsh microclimate (air temperature, humidity, wind speed), and surface water heat storage. Analysis of an ensemble of 17 calibrated model parameters revealed a significant wetland-atmosphere exchange regime shift due to tidal flooding: the salt marsh functioned like a heated, sparse crop during non-flooded periods and like well-watered, evaporatively-cooled grass during floods. An analogous wetland-atmosphere exchange regime shift likely occurs in other systems sustained by short-duration flood events between larger hydrologic events.
Importance of biogeomorphic and spatial properties in assessing a tidal salt marsh vulnerability to sea-level rise
Thorne, Karen M.; Elliott-Fisk, Deborah L.; Wylie, Glenn D.; Perry, William M.; Takekawa, John Y.
We evaluated the biogeomorphic processes of a large (309 ha) tidal salt marsh and examined factors that influence its ability to keep pace with relative sea-level rise (SLR). Detailed elevation data from 1995 and 2008 were compared with digital elevation models (DEMs) to assess marsh surface elevation change during this time. Overall, 37 % (113 ha) of the marsh increased in elevation at a rate that exceeded SLR, whereas 63 % (196 ha) of the area did not keep pace with SLR. Of the total area, 55 % (169 ha) subsided during the study period, but subsidence varied spatially across the marsh surface. To determine which biogeomorphic and spatial factors contributed to measured elevation change, we collected soil cores and determined percent and origin of organic matter (OM), particle size, bulk density (BD), and distance to nearest bay edge, levee, and channel. We then used Akaike Information Criterion (AICc) model selection to assess those variables most important to determine measured elevation change. Soil stable isotope compositions were evaluated to assess the source of the OM. The samples had limited percent OM by weight (-3, indicating that the soils had high mineral content with a relatively low proportion of pore space. The most parsimonious model with the highest AICc weight (0.53) included distance from bay's edge (i.e., lower intertidal) and distance from levee (i.e., upper intertidal). Close proximity to sediment source was the greatest factor in determining whether an area increased in elevation, whereas areas near landward levees experienced subsidence. Our study indicated that the ability of a marsh to keep pace with SLR varied across the surface, and assessing changes in elevation over time provides an alternative method to long-term accretion monitoring. SLR models that do not consider spatial variability of biogeomorphic and accretion processes may not correctly forecast marsh drowning rates, which may be especially true in modified and urbanized estuaries. In light of SLR, improving our understanding of elevation change in these dynamic marsh systems will play a crucial role in forecasting potential impacts to their sustainability and the survival of these ecosystems.
Dynamics of bacterial community succession in a salt marsh chronosequence: evidences for temporal niche partitioning.
Dini-Andreote, Francisco; de Cßssia Pereira e Silva, Michele; Triad¾-Margarit, Xavier; Casamayor, Emilio O; van Elsas, Jan Dirk; Salles, Joana FalcŃo
The mechanisms underlying community assembly and promoting temporal succession are often overlooked in microbial ecology. Here, we studied an undisturbed salt marsh chronosequence, spanning over a century of ecosystem development, to understand bacterial succession in soil. We used 16S rRNA gene-based quantitative PCR to determine bacterial abundance and multitag 454 pyrosequencing for community composition and diversity analyses. Despite 10-fold lower 16S rRNA gene abundances, the initial stages of soil development held higher phylogenetic diversities than the soil at late succession. Temporal variations in phylogenetic ?-diversity were greater at initial stages of soil development, possibly as a result of the great dynamism imposed by the daily influence of the tide, promoting high immigration rates. Allogenic succession of bacterial communities was mostly driven by shifts in the soil physical structure, as well as variations in pH and salinity, which collectively explained 84.5% of the variation concerning community assemblage. The community assembly data for each successional stage were integrated into a network co-occurrence analysis, revealing higher complexity at initial stages, coinciding with great dynamism in turnover and environmental variability. Contrary to a spatial niche-based perspective of bacterial community assembly, we suggest temporal niche partitioning as the dominant mechanism of assembly (promoting more phylotype co-occurrence) in the initial stages of succession, where continuous environmental change results in the existence of multiple niches over short periods of time. PMID:24739625
Crabs Mediate Interactions between Native and Invasive Salt Marsh Plants: A Mesocosm Study
Zhang, Xiao-dong; Jia, Xin; Chen, Yang-yun; Shao, Jun-jiong; Wu, Xin-ru; Shang, Lei; Li, Bo
Soil disturbance has been widely recognized as an important factor influencing the structure and dynamics of plant communities. Although soil reworkers were shown to increase habitat complexity and raise the risk of plant invasion, their role in regulating the interactions between native and invasive species remains unclear. We proposed that crab activities, via improving soil nitrogen availability, may indirectly affect the interactions between invasive Spartina alterniflora and native Phragmites australis and Scirpus mariqueter in salt marsh ecosystems. We conducted a two-year mesocosm experiment consisting of five species combinations, i.e., monocultures of three species and pair-wise mixtures of invasive and native species, with crabs being either present or absent for each combination. We found that crabs could mitigate soil nitrogen depletion in the mesocosm over the two years. Plant performance of all species, at both the ramet-level (height and biomass per ramet) and plot-level (density, total above- and belowground biomass), were promoted by crab activities. These plants responded to crab disturbance primarily by clonal propagation, as plot-level performance was more sensitive to crabs than ramet-level. Moreover, crab activities altered the competition between Spartina and native plants in favor of the former, since Spartina was more promoted than native plants by crab activities. Our results suggested that crab activities may increase the competition ability of Spartina over native Phragmites and Scirpus through alleviating soil nitrogen limitation. PMID:24023926
Classification of salt marsh vegetation using edaphic and remote sensing-derived variables
NASA Astrophysics Data System (ADS)
Hladik, Christine; Alber, Merryl
Salt marsh plant communities are known for their striking patterns of vertical zonation. Two of the most important edaphic parameters that affect species distribution patterns are soil salinity and waterlogging, both of which are related to topographical variations and distance to the water. The primary objective of this study was to evaluate whether information on elevation and distance derived through remote sensing could be used to predict plant distributions in a southeastern United States salt marsh. We classified four marsh vegetation classes (tall Spartina alterniflora, medium S. alterniflora/short S. alterniflora, marsh meadow, and Borrichia frutescens/Juncus roemerianus) based on landscape metrics obtained from a light detection and ranging (LIDAR)-derived digital elevation model (DEM) and compared results to a classification based on field-collected edaphic variables. Our secondary objective was to compare the performance of linear discriminant analysis (LDA) with non-parametric classification and regression trees (CART) for these classifications. Models based on the edaphic variables soil water content, salinity, and redox potential attained accuracies of 0.62 and 0.71 with LDA and CART, respectively. When the remote sensing-derived variables DEM elevation, slope, distance to the mean high water line, and distance to upland area were used, classification accuracies improved to 0.78 for LDA and 0.79 for CART. Our results suggest that remote sensing-derived metrics can capture edaphic gradients effectively, which makes them especially suited to landscape level analyses of salt marsh plant habitats, with potential application for predicting the effects of sea level rise on salt marsh plant distribution.
This research will build upon prior efforts where regression was used to model salt marsh species persistence and productivity along hydrologic and edaphic gradients at the SWB. Upcoming results will enable the optimization of planting combinations at a given salinity leve...
DECEMBER, 1976 MOSQUITO NEWS W6 9 437 BEHAVIORAL CHANGES IN THE SALT MARSH MOSQUITO, AEDES SOLLICITANS, AS A RESULT OF INCREASED PHYSIOLOGICAL AGE' WAYNE'J. CRANS, JERE DOWNING MARC E. SLAFF Mosquito for less than week the inland site and that few bites would be received from mosquitoes. When the nuisance
Critical Bifurcation of Shallow Microtidal Landforms in Tidal Flats and Salt Marshes
Sergio Fagherazzi; Luca Carniello; Luigi D'Alpaos; Andrea Defina
Shallow tidal basins are characterized by extensive tidal flats and salt marshes that lie within specific ranges of elevation, whereas intermediate elevations are less frequent in intertidal landscapes. Here we show that this bimodal distribution of elevations stems from the characteristics of wave induced sediment resuspension, and, in particular, from the reduction of maximum wave height caused by dissipative processes
The effect of fluctuations in tidal inundation frequency on a salt-marsh vegetation
H. Olff; J. P. Bakker; L. F. M. Fresco
Over a period of 15 years recordings were made of the species cover in permanent plots on the salt marsh of one of the West Frisian Islands, Schiermonnikoog (The Netherlands). Correlations between annual changes in the cover of the major species, and fluctuations in the monthly frequency of inundation by seawater were studied. First, a spectral analysis was carried out
Long-term CH3Br and CH3Cl flux measurements in temperate salt marshesĀ
Blei, Emanuel; Heal, Mathew R; Heal, Kate V
Fluxes of CH3Br and CH3Cl and their relationship with potential drivers such as sunlight, temperature and soil moisture, were monitored at fortnightly to monthly intervals for more than two years at two contrasting temperate salt marsh sites...
Temporal and spatial variation in methyl bromide emissions from a salt marshĀ
Drewer, Julia; Heal, Mathew R; Heal, Kate V; Smith, Keith A
measurements of CH3Br emissions from a salt marsh in Scotland (56░00?N, 2░35?W) were made during one year using eight static enclosures. Net emissions showed both strong seasonal and diurnal cycles. Day-to-day maxima in emissions were associated with sunny days...
Variation in insect herbivory across a salt marsh tidal gradient influences plant survival and distribution
Tatyana A. Rand
Herbivore damage and impact on plants often varies spatially across environmental gradients. Although such variation has been hypothesized to influence plant distribution, few quantitative evaluations exist. In this study I evaluated patterns of insect herbivory on an annual forb, Atriplex patula var. hastata, across a salt marsh tidal gradient, and performed experiments to examine potential causes and consequences of variation
A potential mechanism for disturbance-mediated channel migration in a southeastern United States salt marsh
Lottig, Noah R.
salt marsh Noah R. Lottig, Justin M. Fox University of Wisconsin-Madison Center for Limnology 680 North banks can cause the death of below-ground vegetation leading to bare, unstable banks that may slump). Consequently, the failed slump blocks armor the channel banks, resulting in extremely slow erosion and channel
Accumulation, distribution and cellular partitioning of mercury in several halophytes of a contaminated salt marsh
Rita Castro; Sofia Pereira; Ana Lima; Sofia Corticeiro; M¾nica Vßlega; Eduarda Pereira; Armando Duarte; Etelvina Figueira
This work evaluates the role of a plant community in mercury (Hg) stabilization and mobility in a contaminated Portuguese salt marsh. With this aim, the distribution of Hg in below and aboveground tissues, as well as the metal partitioning between cellular fractions (soluble and insoluble) in four different species (Triglochin maritima L., Juncus maritimus Lam, Sarcocornia perennis (Miller) A.J. Scott,
A study on long-term salt-marsh succession using permanent plots
A. J. M. Roozen; V. Westhoff
Succession of plant communities on a salt marsh at the Boschplaat, Terschelling (The Netherlands) is described on the basis of relevķs from permanent plots in three transects, covering a period of almost 30 years. All relevķs were clustered, using a hierarchical fusion technique. Succession has been quantified in terms of transitions between clusters over time in all plots. Analysis of
Patterns in tidal environments: salt-marsh channel networks and vegetation
M. Marani; S. Silverstri; E. Belluco; M. Camuffo; A. D'Alpaos; S. Lanzoni; A. Marani; A. Rinaldo
Salt marshes in tidal environments are characterised by complex patterns both in their geomorphic and ecological features. Such patterns arise through the elaboration of a network structure driven by the tidal forcing and through the interaction between hydrodynamical, geophysical and ecological components (e.g. microphytobenthos and vegetation). This contribution introduces observations of tidal environments from remote sensing and ancillary data collected
Impact of flower harvesting on the salt marsh plant Limonium carolinianum
Reekie, Ed
Impact of flower harvesting on the salt marsh plant Limonium carolinianum Jennifer L. Baltzer of the potentially detrimental effects of seed production on adult survivorship and growth, moderate flower harvesting may have little negative impact on population growth of long-lived perennial plants
Salt-marsh Vegetation and Morphology: Basic Physiology, Modelling and Remote Sensing Observations
Sonia Silvestri; Marco Marani
The state and evolution of a tidal salt marsh are crucially dependent on the interplay between sediment input and transport, eustatism, hydrodynamic regimes and biotic factors (e.g. vegetation colonization). Biotic factors have a decisive influence on sediment deposition, resuspension and compaction but are, in turn, governed by numerous physical factors (e.g. soil salinity and oxygen availability). A model that can
Nitrogen resorption from senescing leaves of three salt marsh plant species
P. Cartaxana; F. Catarino
Seasonalvariation in leaf nitrogen of mature green and senescent leaves and nitrogenresorption efficiency in three plants (Spartina maritima, Halimioneportulacoides and Arthrocnemum perenne) of aTagus estuary salt marsh are reported. Total nitrogen concentrations in greenand senescent leaves were higher during winter (December and March). Soilinorganic nitrogen availability showed an opposite pattern with higherconcentrations during summer (June and September) when total leaf
Technology Transfer Automated Retrieval System (TEKTRAN)
Claviceps purpurea associated with grass hosts in salt marsh habitats, also known as G3 ergot, can be differentiated from C. purpurea infecting grasses in other habitats using genetic, chemical and morphological criteria. However, only morphological analysis can be used on herbarium specimens, which...
Using Nitrogen Stable Isotope Tracers to Track Climate Change Impacts on Coastal Salt Marshes
Climate change impacts on coastal salt marshes are predicted to be complex and multi-faceted. In addition to rising sea level and warmer water temperatures, regional precipitation patterns are also expected to change. At least in the Northeast and Mid-Atlantic U.S., more severe s...
Patterns in tidal environments: salt-marsh channel networks and vegetation
Consorzio Venezia Nuova
Salt marshes in tidal environments are characterised by complex patterns both in their geomorphic and ecological features. Such patterns arise through the elaboration of a network structure driven by the tidal forcing and through the interaction between hydrodynamical, geophysical and ecological components (e.g. microphytobenthos and vegetation). This contribution introduces observations of tidal environments from remote sensing and ancillary data collected
The impact of tidal inundation on salt marsh vegetation after de-embankment on Langeoog Island, GermanyŚsix years time series of permanent plots
J. W. Barkowski; K. Kolditz; H. Brumsack; H. Freund
Salt marsh succession after de-embankment was monitored on the East Frisian barrier island Langeoog by investigating permanent\\u000a plots. Seventy years after embankment salt marsh plants were once again influenced mainly by the tidal regime. From 2002 to\\u000a 2004 the former high marsh and glycophytic vegetation died out and was replaced by species of lower salt marsh zones. Nitrophytic\\u000a halophytes like
Recommended design for more accurate duplication of natural conditions in salt marsh creation.
Darnell, T M; Smith, E H
Construction of 653 ha of salt marsh habitat from dredged material near the Aransas National Wildlife Refuge, Texas, has been proposed, with the goal of increasing the area of habitat available to endangered whooping cranes ( Grus americana). We assessed prototype created wetlands, and their similarity to natural reference sites, in terms of topography, vegetation, and hydrology. The created sites were steeply sloped relative to natural sites and were dominated by monotypic stands of Spartina alterniflora. Natural sites were dominated by vegetation more tolerant of desiccation and hypersalinity and by unvegetated salt pans. Differences in vegetation communities and distributions of habitat types resulted from efforts to enhance habitat diversity in created marsh cells through manipulation of marsh topography. However, the scale at which this diversity occurred in natural marsh of the study area was not considered. When constructing wetlands in cellular configurations, we recommend creation of large complexes of adjoining, hydrologically linked, cells wherein the desired habitat diversity is created at the scale of the entire complex, rather than within a single cell. Suggested design modifications would increase the similarity of created marshes to natural reference sites, potentially improving habitat function. PMID:11992173
Seasonal and topographic variations in porewaters of a southeastern USA salt marsh as revealed by voltammetric profilingå
Bull, David C; Taillefert, Martial
We report electrochemical profiles from unvegetated surficial sediments of a Georgia salt marsh. In creek bank sediments, the absence of ?H2S or FeSaq and the presence of Fe(III)¢organic complexes suggest that Mn and Fe reduction dominates over at least the top ca. 5 cm of the sediment column, consistent with other recent results. In unvegetated flats, accumulation of ?H2S indicates that SO42- reduction dominates over the same depth. A summer release of dissolved organic species from the dominant tall form Spartina alterniflora, together with elevated temperatures, appears to result in increased SO42- reduction intensity and hence high summer concentrations of ?H2S in flat sediments. However, increased bioturbation and/or bioirrigation seem to prevent this from happening in bank sediments. Studies of biogeochemical processes in salt marshes need to take such spatial and temporal variations into account if we are to develop a good understanding of these highly productive ecosystems. Furthermore, multidimensional analyses are necessary to obtain adequate quantitative pictures of such heterogeneous sediments. PMID:16759419
The Effect of Nitrogen Enrichment on C1-Cycling Microorganisms and Methane Flux in Salt Marsh Sediments
Irvine, Irina C.; Vivanco, LucĒa; Bentley, Peris N.; Martiny, Jennifer B. H.
Methane (CH4) flux from ecosystems is driven by C1-cycling microorganisms ¢ the methanogens and the methylotrophs. Little is understood about what regulates these communities, complicating predictions about how global change drivers such as nitrogen enrichment will affect methane cycling. Using a nitrogen addition gradient experiment in three Southern California salt marshes, we show that sediment CH4 flux increased linearly with increasing nitrogen addition (1.23??g CH4?m?2?day?1 for each g?N?m?2?year?1 applied) after 7?months of fertilization. To test the reason behind this increased CH4 flux, we conducted a microcosm experiment altering both nitrogen and carbon availability under aerobic and anaerobic conditions. Methanogenesis appeared to be both nitrogen and carbon (acetate) limited. N and C each increased methanogenesis by 18%, and together by 44%. In contrast, methanotrophy was stimulated by carbon (methane) addition (830%), but was unchanged by nitrogen addition. Sequence analysis of the sediment methylotroph community with the methanol dehydrogenase gene (mxaF) revealed three distinct clades that fall outside of known lineages. However, in agreement with the microcosm results, methylotroph abundance (assayed by qPCR) and composition (assayed by terminal restriction fragment length polymorphism analysis) did not vary across the experimental nitrogen gradient in the field. Together, these results suggest that nitrogen enrichment to salt marsh sediments increases methane flux by stimulating the methanogen community. PMID:22470369
Feedbacks underlie the resilience of salt marshes and rapid reversal of consumer-driven die-off.
Altieri, Andrew H; Bertness, Mark D; Coverdale, Tyler C; Axelman, Eric E; Herrmann, Nicholas C; Szathmary, P Lauren
Understanding ecosystem resilience to human impacts is critical for conservation and restoration. The large-scale die-off of New England salt marshes was triggered by overfishing and resulted from decades of runaway crab grazing. In 2009, however, cordgrass began to recover, decreasing die-off -40% by 2010. We used surveys and experiments to test whether plant-substrate feedbacks underlie marsh resilience. Initially, grazer-generated die-off swept through the cordgrass, creating exposed, stressful peat banks that inhibited plant growth. This desertification cycle broke when banks eroded and peat transitioned into mud with fewer herbivores, less grazing, and lower physical stress. Cordgrass reestablished in these areas through a feedback where it engineered a recovery zone by further ameliorating physical stresses and facilitating additional revegetation. Our results reveal that feedbacks can play a critical role in rapid, reversible ecosystem shifts associated with human impacts, and that the interplay of facilitative and consumer interactions should be incorporated into resilience theory. PMID:23951724
Influences of Salinity Variations on Pore-water Flow in Salt Marshes
NASA Astrophysics Data System (ADS)
Shen, C.; Jin, G.; Xin, P.; Li, L.
Salt marshes are important wetlands at the ocean-land interface with various ecological functions, serving as essential habitats for intertidal fauna, affecting the productivity of coastal waters through nutrient exchange, moderating the greenhouse gas emission and global warming. They are influenced by various physical and biogeochemical processes, among which the pore-water flow and associated solute transport processes play an important role in determining the material exchange between marsh soils and coastal water. Previous studies have examined such processes under the solo or combined effects of tidal fluctuation, evapotranspiration, stratigraphy, inland freshwater input, and topography. However, these investigations have neglected the spatial and temporal salinity variations in surface water and pore-water, which commonly exist in salt marshes due to the impacts of tidal inundation, precipitation and evapotranspiration. The density contrast between the surface water and pore-water may lead to significant modifications of the pore-water flow. Based on results from laboratory experiments and numerical simulations, we will demonstrate that: (1) under upward salinity gradients, flow instabilities in the form of fingers occur once the salinity contrast reaches a certain level, whereas under downward salinity gradients the system is stable; (2) because of the strong tidally-induced advective process occurring near the creek, both the number and size of fingers change gradually from the near-creek zone to the marsh interior; and (3) both upward and downward salinity gradients enhance the exchange between the surface water and pore-water in the marsh sediments. Keywords: Salt marshes; density effect; salinity gradient; pore-water flow; fingers. Instabilities under upward salinity gradient Stable system under downward salinity gradient
Using Projections of Tidal Marsh Ecosystem Response to Sea-Level Rise to Guide Adaptation Planning
NASA Astrophysics Data System (ADS)
Veloz, S.; Nur, N.; Salas, L. A.; Stralberg, D.; Jongsomjit, D.; Wood, J.; Liu, L.; Ballard, G.
The large uncertainty associated with estimating the effects of sea-level rise and climate change on tidal marsh ecosystems exacerbates the difficulty in planning for their effective conservation. To address this uncertainty, we modeled the distribution and abundance of tidal marsh bird species in the San Francisco Estuary for the period 2010 to 2110 in relation to projected changes in sea-level rise, salinity, and sediment availability using four future scenarios with assumptions of low or high suspended sediment concentrations and low or high rates of sea-level rise (0.52 or 1.65 m/100 yr). We used the projections of bird populations the modeled uncertainty to develop spatially explicit priorities for conservation and restoration using Zonation conservation planning software. In our models, marsh bird population generally declined from current levels due to the conversion of high and mid-marsh habitat to low-marsh and mudflats and changes in spring and summer salinity. High sea-level rise scenarios had the biggest impact on bird populations, although the effects were muted under high sediment availability scenarios. There was considerable variation in bird population projections among the four future scenarios we tested and the uncertainty tended to increase from 2030 to 2110. Because so little tidal marsh habitat currently remains in the San Francisco Estuary, the spatial prioritization found that all areas currently open to tidal influence were high priorities for conservation. We repeated this prioritization exercise with all barriers to tidal flow (e.g. levees) removed and identified important locations in which restoration by breaching levees would most efficiently provide long-term benefit to tidal marsh bird populations. The projected species distributions and changes in tidal marsh elevations are available in the form of interactive maps and downloadable GIS layers at: www.prbo.org/sfbayslr. This website can help managers plan effective conservation and restoration strategies to foster adaptation to the effects of future climate change.
The new CutSprof sampling tool and method for micromorphological and microfacies analyses of subsurface salt marsh sediments, Algarve, Portugal
NASA Astrophysics Data System (ADS)
Ara·jo-Gomes, JoŃo; Ramos-Pereira, Ana
A new tool and method for collecting undisturbed subsurface samples in estuarine environments by means of trenching, timbering and sectioning is presented. Smoothing of sidewalls is achieved by a so-called cutting sediment profiler (CutSprof), while water draining into the trench is cleared by pumping. From smoothed sidewall sections, undisturbed thin sediment slices can then be collected for micromorphological and microfacies analyses. Results demonstrating the successful application of this procedure are presented for salt marshes of the Bensafrim River estuary (Lagos, Algarve, Portugal). In addition to palaeo-reconstructions in salt marsh settings, the CutSprof would be highly suitable in various other research domains as well as for environmental management purposes, particularly where sampling below the groundwater table is desirable to explore, for example, animal-sediment relationships in tidal-flat and mangrove ecosystems as well as the dynamics of coastal wetlands today threatened by ever-increasing anthropogenic influence.
The influence of mosquito control recirculation ditches on plant biomass, production and composition in two San Francisco Bay salt marshes
NASA Astrophysics Data System (ADS)
Balling, Steven S.; Resh, Vincent H.
Vegetation of two San Francisco Bay, California, U.S.A. tidal marshes was examined to determine the effects of recirculation ditches designed to eliminate mosquito-breeding. Salicornia virginica L. biomass and production in Petaluma Marsh and plant species composition in Suisun Marsh were measured with respect to distance from ditches and natural channels. In Petaluma Marsh, both annual above-ground production estimates and infrared aerial photographs indicated that S. virginica growth rates were higher near ditches than in the open marsh. In the floristically diverse, less saline Suisun Marsh, there was a displacement of the more salt tolerant S. virginica by the less tolerant Juncus balticus Willd. and a significantly greater number of species near the ditches. Results in both marshes are correlated with low groundwater salinities near ditches and suggest that tidal circulation within ditches locally ameliorates extremes in soil conditions.
Ecology of irregularly flooded salt marshes of the northeastern Gulf of Mexico: a community profile
Stout, J.P.
The salt marshes of the northeastern Gulf of Mexico are distinguished by irregular flooding, low energy wave and tidal action, and long periods of exposure. The plant community is most often dominated by black needlerush (Juncus roemerianus), the species of focus in this synthesis. Distinct marsh zones include those dominated by Juncus and Spartina alterniflora at low elevations, sparsely vegetated salt flats, and higher elevation salt meadows of Juncus and Spartina patens. A diverse microbial and algal assemblage is also present. A diverse fauna has adapted to the physical rigors of these marshes. Zooplankton are dominated by the larvae of fiddler crabs and other decapods. The meiofauna consist primarily of nematodes and harpacticoid copepods. Macroinvertebrates are represented by crustaceans (especially mollusks and crabs), annelids, and insects. Grass shrimp, blue crabs, and other crustaceans are seasonally abundant in marsh creeks, as are a number of resident and migratory fish species. Birds comprise one of the larger herbivore groups and are also significant at higher tropic levels as top carnivores. Muskrat and nutria are important mammals. 43 figs., 38 tabs.
The value of salt marsh edge vs interior as a habitat for fish and decapod crustaceans in a Louisiana tidal marsh
G. W. Peterson; R. E. Turner
Flume nets of various lengths and a 3-m seine were used to sample the fishes and macrocrustaceans using a flooded Louisiana\\u000a salt marsh and the adjacent tidal creek. The experiment allowed for species-specific comparisons of the flooded marsh at the\\u000a creek edge versus the interior. Of the 37,667 organisms collected in flume nets from January through November 1989, 89% were
A comparative investigation of the effects of south Louisiana crude oil on the vegetation of fresh, brackish and salt marshes
Qianxin Lin; Irving A. Mendelssohn
The impact of south Louisiana crude oil on the dominant vegetation, Spartina alterniflora, Spartina patens and Sagittaria lancifolia, of three types of coastal wetlands, salt, brackish and freshwater marshes, respectively, was studied. In the greenhouse, south Louisiana crude oil was applied to natural marsh sods at rates of 0, 4, 8, 16 and 24 l m?2. The photosynthetic rate of
A comparison of bird use and species diversity of created and natural salt marshes in the Galveston Bay complex, Texas
Melvin, Stefani Lynn
Birds were censused in seven natural and seven created salt marshes in lower Galveston Bay from October 1990 through September 1991 to evaluate differences in bird use due to marsh origin, size, and age. Birds were grouped by foraging method, prey...
Salt marshes are considered important foraging and predator refuge areas for fish, but these functions are rarely measured. The goal of this study was to examine the relationship between the structural complexity of the habitat and fish size in marshes subjected to different wat...
Spartina alterniflora genotype influences facilitation and suppression of high marsh species colonizing an early successional salt marsh
Proffitt, C.E.; Chiasson, R.L.; Owens, A.B.; Edwards, K.R.; Travis, S.E.
1. Genetically based phenotypic and ecotypic variation in a dominant plant species can influence ecological functions and patterns of recruitment by other species in plant communities. However, the nature and degree of importance of genotypic differences is poorly understood in most systems. 2. The dominant salt marsh species, Spartina alterniflora, is known to induce facultative and competitive effects in different plant species, and the outcomes of interactions can be affected by nutrients and flooding stress. Clonal genotypes, which maintained their different plant architecture phenotypes throughout 31 months of a field experiment, underwent considerable genet-specific senescence in their centres over the last 12 months. 3. Different clonal genotypes and different locations (robust edges vs. senescent centres) permitted significantly different levels of light penetration of the canopy (14.8-77.6%), thus establishing spatial heterogeneity for this important environmental factor. 4. S. alterniflora clonal genotype influenced the degree of suppression of the previously dominant Salicornia bigelovii as well as facilitation of recruitment and growth by other plant species. Aster subulatus and Atriplex, patula performed better in Spartina clone centres, and experienced reduced growth in Salicornia-dominated areas. 5. Four other high marsh species (Borrichia frutescens, Aster tenuifolius, Iva frutescens and Limonium carolinianum) colonized only into Spartina clones but not into the Salicornia-dominated area. 6. These results suggest that differences in clone size, centre senescence, stem density, height, total stem length and biomass in different genotypes of a dominant marsh plant species can influence recruitment and growth of other plant species. The spatial pattern of habitat heterogeneity is, at least in part, dependent on the genotypic diversity, and possibly the genetic diversity, of such foundation species. 7. We hypothesize that as genotypic diversity increases in populations of a dominant plant species like S. alterniflora, the number and diversity of interactions with other species will increase as well. ?? 2005 British Ecological Society.
Impacts of Fertilization on Rates of Autotrophic N2 Fixation in Salt Marshes and Cranberry Bogs of Massachusetts
Vallino, Joseph J.
and a cultivated freshwater system, salt marshes and cranberry bogs in the Falmouth area provide an opportunity and cranberry bogs in the Falmouth, MA area. High annual rates of fixation, primarily by blue-green algae
Modification of Sediments and Macrofauna by an Invasive Marsh Plant
T. S. Talley; L. A. Levin
Invasive grasses have recently altered salt marsh ecosystems throughout the northern hemisphere. On the eastern seaboard of\\u000a the USA, Phragmites australis has invaded both brackish and salt marsh habitats. Phragmites australis influence on sediments and fauna was investigated along a salinity and invasion-age gradient in marshes of the lower Connecticut\\u000a River estuary. Typical salinities were about 19¢24?ppt in Site I,
Microalgal productivity, community composition, and pelagic food web dynamics in a subtropical, turbid salt marsh isolated from freshwater inflow
Elizabeth Fejes; Daniel Roelke; George Gable; James Heilman; Kevin McInnes; David Zuberer
Carbon entering the food web originating from microalgal productivity may be as important to salt marsh consumers as carbon\\u000a originating from vascular plant production. The objective of this study was to further our understanding of the role played\\u000a by microalgae in salt marshes. We focused on microalgal productivity, community dynamics, and pelagic food web linkages. Across\\u000a three consecutive springs (2001¢2003),
High site fidelity and low site connectivity in temperate salt marsh fish populations: a stable isotope approach
Benjamin C. GreenDavid; David J. Smith; Jonathan Grey; Graham J. C. Underwood
Adult and juvenile fish utilise salt marshes for food and shelter at high tide, moving into adjacent sublittoral regions during\\u000a low tide. Understanding whether there are high levels of site fidelity for different species of coastal fish has important\\u000a implications for habitat conservation and the design of marine protected areas. We hypothesised that common salt marsh fish\\u000a species would demonstrate
Differential effects of salinity and soil saturation on native and exotic plants of a coastal salt marsh
Nathan L. Kuhn; Joy B. Zedler
In many southern California salt marshes, increased freshwater inflows have promoted the establishment of exotic plant species.\\u000a A comparative study showed that a native, perennial, high marsh dominant,Salicornia subterminalis, and an invasive, exotic annual grass,Polypogon monspeliensis, responded differently to soil salinity and saturation.Salicornia subterminalis seeds and young plants were more salt tolerant, and the native grew best at high salinities
The effect of successional stage and salinity on the vertical distribution of seeds in salt marsh soils
Reza Erfanzadeh; Frederik Hendrickx; Jean-Pierre Maelfait; Maurice Hoffmann
Seed bank density and similarity between above-ground vegetation and seed bank with depth were compared between two adjacent salt marshes that differ in age. In addition, the effect of salinity on the variation in seed bank density and similarity between above-ground vegetation and seed bank with depth was compared between euhaline against mesohaline conditions in three salt marshes.Ten plots of
Ecomorphodynamic evolution of salt marshes: Experimental observations of bank retreat processes
NASA Astrophysics Data System (ADS)
Francalanci, S.; Bendoni, M.; Rinaldi, M.; Solari, L.
This paper addresses the problem of the erosion of salt marsh edges. Flume laboratory experiments were carried out aimed at reproducing the instability and retreat of the scarps that typically delimit the salt marshes under the attack of wind waves during the tidal cycle. The bank model and hydrodynamic forcing in the flume were such as to simulate the conditions observed in the field in Venice Lagoon. Experiments were conducted for the same hydrodynamic forcing in the case of two identical banks but with and without the inclusion of the vegetation. Experimental results show that bank retreat involves a variety of processes (including particle erosion, cantilever and slide failures). The effect of the vegetation was to produce a delay in the mass failures, related to a certain growth of plant roots, thus providing an overall stabilizing effect. Bank instability was related to the formation of tension cracks at the bank top and to the impulsive effects associated with wave energy dissipation.
Statistical methods for analysis of seasonal modifications in the salt marshes of the Venice lagoon
M. Camuffo; F. Benvenuto; M. Marani Abbadessa; L. Modenese; A. Marani
Purpose ¢ To define synthetic indices of changes of vegetation coverage on salt marshes of the Venice lagoon that might be used to model changes of the entire basin. Design\\/methodology\\/approach ¢ Remote sensing data from the satellite sensor QuickBird were processed to retrieve vegetation coverage in different seasons, i.e. different phenological stages of the halophytic vegetation. These changes have been
Nesting habitat of BeldingÆs Savannah sparrows in coastal salt marshes
Abby N. Powell
Although the BeldingÆs Savannah sparrow (Passerculus sandwichensis beldingl) is listed as endangered in California, little is known about the factors that affect its abundance and distribution. Numbers\\u000a of breeding pairs, nesting territory sizes, and vegetation characteristics were measured at fourteen study plots in two southern\\u000a California coastal wetlands, Tijuana Estuary and Los Pe±asquitos Lagoon. Sparrows nested in middle salt marsh
Effects of nitrogen addition on the growth of the salt marsh grass Elymus athericus
Peter C. Leendertse; Jelte Rozema; Adrie Andrea
Effects of nitrogen addition on the growth of the salt marsh grassElymus athericus were studied under greenhouse conditions. The addition of inorganic nitrogen (in the form of nitrate or ammonium and ranging\\u000a from 0¢24 g N\\/m2) stimulated the growth ofElymus athericus at the highest addition. Addition of nitrogen led to an increase of the soil nitrate concentrations both in the
A comparative study of the tolerance of salt marsh plants to manganese
A. Cooper
Summary Salicornia europaea, Puccinellia maritima, Triglochin maritima, Aster tripolium, Plantago maritima, Armeria maritima, Juncus gerardii andFestuca rubra, collected as seed from a salt marsh at Portaferry, County Down, were grown on saline (340 mM NaCl) and non saline nutrient solutions at five concentrations of manganese sulphate (0.025¢10.0 mM). After an eight week growing period, shoot and root yields and the
Pyrite formation and the measurement of sulfate reduction in salt marsh sediments
A new method was used to study the formation of pyrite plus elemental sulfur during ┬│ŌüĄSOŌ\\/sup 2 -\\/ reduction experiments in salt marsh sediments: the reduction with chromium(II) of pyrite and elemental sulfur to hydrogen sulfide. It is both more specific and more sensitive than the previous method, the oxidation of pyrite and elemental sulfur to sulfate by aqua regia,
Tidal Creek and Salt Marsh Sediments in South Carolina Coastal Estuaries: II. Distribution of Organic Contaminants
D. M. Sanger; A. F. Holland; G. I. Scott
.ĀĀ Twenty-eight tidal creeks along the South Carolina coast were sampled during the summer of 1995 to determine the levels\\u000a of sediment contamination including organic chemicals (i.e., polycyclic aromatic hydrocarbons [PAHs], polychlorinated biphenyls [PCBs], and DDT and its metabolites) associated with different\\u000a types and varying levels of watershed development (i.e., industrial\\/urban, suburban, forested, and salt marsh). Organic analysis utilized high-performance
Patterns of sulfate reduction and the sulfur cycle in a South Carolina salt marsh
Gary M. King
Rates of sulfate reduction and the magnitude of various sediment parameters related to the sulfur cycle were measured at about quarterly intervals for a 3-yr period at sites in a South Carolina salt marsh containing tall- or short-form Spartina alternij70ra. Sulfate reduction rates were greater at all times in the short-form sites and decreased markedly with depth. Seasonal changes were
Long-term CH3Br and CH3Cl flux measurements in temperate salt marshes
NASA Astrophysics Data System (ADS)
Blei, E.; Heal, M. R.; Heal, K. V.
Fluxes of CH3Br and CH3Cl and their relationship with potential drivers such as sunlight, temperature and soil moisture, were monitored at fortnightly to monthly intervals for more than two years at two contrasting temperate salt marsh sites in Scotland. Manipulation experiments were conducted to further investigate possible links between drivers and fluxes. Mean (▒ 1 sd) annually and diurnally-weighted net emissions from the two sites were found to be 300 ▒ 44 ng m-2 h-1 for CH3Br and 662 ▒ 266 ng m-2 h-1 for CH3Cl. A tentative scale-up indicates that salt marshes account for 0.5-3.2% and 0.05-0.33%, respectively, of currently-estimated total global production of these two gases, in line with previous findings from this and other research groups, but consistently lower than past global scale-up estimates from Southern Californian salt marshes. Fluxes followed both seasonal and diurnal trends with highest fluxes during summer days and lowest (negative) fluxes during winter nights. Statistical analysis generally did not demonstrate a strong link between temperature or sunlight levels and methyl halide fluxes, although it is likely that temperatures have a weak direct influence on emissions, and both certainly have indirect influence via the annual and daily cycles of the vegetation. CH3Cl flux magnitudes from different measurement locations depended on the plant species enclosed whereas such dependency was not discernible for CH3Br fluxes. In 14 out of 19 collars CH3Br and CH3Cl net fluxes were significantly correlated. The CH3Cl/CH3Br net-emission mass ratio was 2.2, a magnitude lower than mass ratios of global methyl halide budgets (~22) or emissions from tropical rainforests (~60). This is likely due to preference for CH3Br production by the relatively high bromine content in the salt marsh plant material.
Phylogenetic Diversity of Archaea in Sediment Samples from a Coastal Salt Marsh
The Archaea present in salt marsh sediment samples from a tidal creek and from an adjacent area of vegetative marshland, both of which showed active methanogenesis and sulfate reduction, were sampled by using 16S rRNA gene libraries created with Archaea-specific primers. None of the sequences were the same as reference sequences from cultured taxa, although some were closely related to
Beneath the Salt Marsh Canopy: Loss of Soil Strength with Increasing Nutrient Loads
R. Eugene Turner
Although the broadly observed increase in nutrient loading rates to coastal waters in the last 100Āyears may increase aboveground\\u000a biomass, it also tends to increase soil metabolism and lower root and rhizome biomassŚresponses that can compromise soil strength.\\u000a Fourteen different multiyear field combinations of nutrient amendments to salt marshes were made to determine the relationship\\u000a between soil strength and various
Recommended Design for More Accurate Duplication of Natural Conditions in Salt Marsh Creation
Traci M. Darnell; Elizabeth H. Smith
Construction of 653 ha of salt marsh habitat from dredged material near the Aransas National Wildlife Refuge, Texas, has been\\u000a proposed, with the goal of increasing the area of habitat available to endangered whooping cranes (Grus americana). We assessed prototype created wetlands, and their similarity to natural reference sites, in terms of topography, vegetation,\\u000a and hydrology. The created sites were
Bacterial community response to petroleum contamination and nutrient addition in sediments from a temperate salt marsh.
Ribeiro, Hugo; Mucha, Ana P; Almeida, C Marisa R; Bordalo, Adriano A
Microbial communities play an important role in the biodegradation of organic pollutants in sediments, including hydrocarbons. The aim of this study was to evaluate the response of temperate salt marsh microbial communities to petroleum contamination, in terms of community structure, abundance and capacity to degrade hydrocarbons. Sediments un-colonized and colonized (rhizosediments) by Juncus maritimus, Phragmites australis and Triglochin striata were collected in a temperate estuary (Lima, NW Portugal), spiked with petroleum under variable nutritional conditions, and incubated for 15 days. Results showed that plant speciation emerged as the major factor for shaping the rhizosphere community structure, overriding the petroleum influence. Moreover, when exposed to petroleum contamination, the distinct salt marsh microbial communities responded similarly with (i) increased abundance, (ii) changes in structure, and (iii) decreased diversity. Communities, particularly those associated to J. maritimus and P. australis roots displayed a potential to degrade petroleum hydrocarbons, with degradation percentages between 15% and 41%, depending on sediment type and nutritional conditions. In conclusion, distinct salt marsh microbial communities responded similarly to petroleum contamination, but presented different pace, nutritional requirements, and potential for its biodegradation, which should be taken into account when developing bioremediation strategies. PMID:23707865
Evaluation of the ability of two plants for the phytoremediation of Cd in salt marshes
NASA Astrophysics Data System (ADS)
Nunes da Silva, Marta; Mucha, Ana P.; Rocha, A. Cristina; Silva, Carla; Carli, Carolina; Gomes, Carlos R.; Almeida, C. Marisa R.
Several salt marsh plant species have shown to be able to uptake and concentrate metals in their tissues, showing potential for metal phytoremediation. However, studies in controlled conditions, mimicking as much as possible the plants natural environment, are needed to confirm this potential. For the present study, Juncus maritimus and Phragmites australis were collected in an estuary together with the sediment surrounding their roots, put in vessels and maintained in greenhouses under estuarine tidal simulation. After 3 weeks of acclimation, vessels were spiked with two different cadmium concentrations. After 2 months, cadmium was assessed in plant tissues and sediments. Results indicate that both plant species were able to uptake and translocate cadmium into their tissues, contributing also to retain it in rhizosediments and thus reducing the available amount of metal in the environment. Metal was preferentially accumulated in belowground structures, in concentrations not directly proportional to the amount of cadmium present in the sediment. Although no visual toxicity signs were observed, some defence mechanisms were triggered as observed by the changes in carotenoids, lignin, total soluble phenolic compounds and thiolic compounds levels, this response differing between plant species. This work shows that these two salt marsh plants can contribute for the retention of cadmium in salt marshes being useful for the phytostabilization of this metal in estuarine environments.
Tidal Flooding and Vegetation Patterns in a Salt Marsh Tidal Creek Imaged by Low-altitude Balloon Aerial Photography
NASA Astrophysics Data System (ADS)
White, S. M.; Madsen, E.
Inundation of marsh surfaces by tidal creek flooding has implications for the headward erosion of salt marsh creeks, effect of rising sea levels, biological zonation, and marsh ecosystem services. The hydroperiod; as the frequency, duration, depth and flux of water across the marsh surface; is a key factor in salt marsh ecology, but remains poorly understood due to lack of data at spatial scales relevant to tracking the spatial movement of water across the marsh. This study examines how hydroperiod, drainage networks, and tidal creek geomorphology on the vegetation at Crab Haul Creek. Crab Haul Creek is the farthest landward tidal basin in North Inlet, a bar-built estuary in South Carolina. This study measures the hydroperiod in the headwaters Crab Haul Creek with normal and near-IR photos from a helium balloon Helikite at 75-100 m altitude. Photos provide detail necessary to resolve the waterline and delineate the hydroperiod during half tidal cycles by capturing the waterline hourly from the headwaters to a piezometer transect 260 meters north. The Helikite is an ideal instrument for local investigations of surface hydrology due to its maneuverability, low cost, ability to remain aloft for extended time over a fixed point, and ability to capture high-resolution images. Photographs taken from aircraft do not provide the detail necessary to determine the waterline on the marsh surface. The near-IR images make the waterline more distinct by increasing the difference between wet and dry ground. In the headwaters of Crab Haul Creek, individual crab burrows are detected by automated image classification and the number of crab burrows and their spatial density is tracked from January-August. Crab burrows are associated with the unvegetated region at the creek head, and we relate their change over time to the propagation of the creek farther into the tidal basin. Plant zonation is influenced by the hydroperiod, but also may be affected by salinity, water table depth, and soil water content. These other factors are all directly affected by the hydroperiod, creating a complex system of feedbacks. Inundation frequencies show a pronounced relationship to zonation. Creek bank height and the hydroperiod have a curvilinear relationship at low bank heights such that small decreases in creek bank height can result in large increases in inundation frequency. Biological zonation is not simply a result of bank height and inundation frequency, other contributing factors include species competition, adaptability, and groundwater flow. Vegetation patterns delineated by a ground-based GPS survey and image classification from the aerial photos show that not all changes in eco-zonation are a direct function of elevation. Some asymmetry across the creek is observed in plant habitat, and eliminating topography (and thereby tidal inundation) as a factor, we attribute the remaining variability to groundwater flow.
The flux of methyl chloride along an elevational gradient of a coastal salt marsh, Eastern China
NASA Astrophysics Data System (ADS)
Wang, Jinxin; Li, Rongjin; Guo, Yingyan; Qin, Pei; Sun, Shucun
Salt marshes have been suggested to be a large potential source for methyl chloride (CH 3Cl) that is the major natural carrier of chlorine to the stratosphere. However, the global budget of this trace gas is uncertain, and the empirical field data are still lacking. In this study, CH 3Cl fluxes were measured seasonally using static flux chambers from April 2004 to January 2005, along an elevational gradient of a coastal salt marsh in eastern China. To estimate the contribution of higher plants to the flux, plant aboveground biomass was experimentally removed and the flux difference between the treatment and the intact was examined. In addition, the flux was analyzed in relation to soil and weather conditions. Along the elevational gradient, the salt marsh generally functioned as a net sink in the growing season (from April to October 2004). The flux of CH 3Cl ranged between -1.27 and -29.33 ?mol m -2 d -1 (positive for emission and negative for consumption), and the maximum negative rates occurred at the mudflat and the cordgrass ( Spartina alterniflora) marsh. However, the measurements made during inundation indicated that the mudflat was a net source of the gas. In the non-growing season (from November to March), the vegetated flat, when frozen, was a minor source of methyl chloride, with an emission rate ranging from 0.27 to 9.13 ?mol m -2 d -1. However, the measurements made during non-frozen periods indicate that the mudflat was a minor sink of methyl chloride. Overall, the study marsh was a large net sink for the gas because the magnitude of the consumption rates was lager than that of emission, and because the duration of the growing season was longer than that of the non-growing season. Plant aboveground biomass had a great effect on the flux. Comparative analyses showed that higher plants were present as an important source of CH 3Cl, and it could balance 17.26-67.66% of the soil consumption. The net CH 3Cl consumption rate was negatively correlated to soil dissolved salt content and light intensity, but it was positively correlated to soil temperature, soil organic matter content, and ambient atmospheric concentration of CH 3Cl. This suggests that the overall net consumption of CH 3Cl observed in the study marsh may result from the high ambient atmospheric concentration that ranged between 1.3 and 58.5 ppb, and enriched soil organic matter that feed the soil microorganisms using CH 3Cl as a sole source for both carbon and energy.
Biogeochemical and hydrological controls on fate and distribution of trace metals in oiled Gulf salt marshes
NASA Astrophysics Data System (ADS)
Keevan, J.; Natter, M.; Lee, M.; Keimowitz, A.; Okeke, B.; Savrda, C.; Saunders, J.
On April 20, 2010, the drilling rig Deepwater Horizon exploded in the Gulf of Mexico, resulting in the release of approximately 5 million barrels of crude oil into the environment. Oil and its associated trace metals have been demonstrated to have a detrimental effect on coastal wetland ecosystems. Wetlands are particularly susceptible to oil contamination because they are composed largely of fine-grained sediments, which have a high capacity to adsorb organic matter and metals. The biogeochemical cycling of trace metals can be strongly influenced by microbial activity, specifically those of sulfate- and iron-reducing bacteria. Microbial activity may be enhanced by an increase in amounts of organic matter such as oil. This research incorporates an assessment of levels of trace metals and associated biogeochemical changes from ten coastal marshes in Alabama, Mississippi, and Louisiana. These sampling sites range in their pollution levels from pristine to highly contaminated. A total digestion analysis of wetland sediments shows higher concentrations of certain trace metals (e.g., Ni, Cu, Pb, Zn, Sr, Co, V, Ba, Hg, As) in heavily-oiled areas compared to less-affected and pristine sites. Due to chemical complexation among organic compounds and metals, crude oils often contain elevated levels (up to hundreds of mg/kg) of trace metals At the heavily-oiled Louisiana sites (e.g., Bay Jimmy, Bayou Dulac, Bay Batiste), elevated levels of metals and total organic carbon have been found in sediments down to depths of 30 cm. Clearly the contamination is not limited to shallow sediments and oil, along with various associated metals, may be invading into deeper (pre-industrial) portions of the marsh sediments. Pore-waters extracted from contaminated sediments are characterized by very high levels of reduced sulfur (up to 80 mg/kg), in contrast to fairly low ferrous iron concentrations (<0.02 mg/kg). The influx of oil into the wetlands might provide the initial substrate and carbon source for stimulating sulfate-reducing bacteria. The high sulfur levels, coupled with the low levels of iron, indicate that iron-reducing bacteria are outcompeted by sulfate reducers in oiled salt marshes. Moreover, pore-water pH values show a general increasing trend (ranging from 6.6 to 8.0) with depth, possibly reflecting the combined effects of bacterial sulfate reduction and saltwater intrusion at depth. Despite high levels of trace metals in bulk sediments, concentrations of trace metals dissolved in pore-waters are generally low. It is very likely that high organic matter content and bacterially-mediated sulfate reduction promote metal retention through the formation of sulfide solids. Framboidal pyrites, as well as other sulfides, have been identified, and are currently undergoing XRD, SEM, and EDAX analyses. Continued research is needed to monitor possible re-mobilization of trace metals in changing redox and biogeochemical conditions.
The South Florida Ecosystem Assessment Project is an innovative, large-scale monitoring and assessment program designed to measure current and changing conditions of ecological resources in South Florida using an integrated holistic approach. This data set contains results for f...
The South Florida Ecosystem Assessment Project is an innovative, large-scale monitoring and assessment program designed to measure current and changing conditions of ecological resources in South Florida using an integrated holistic approach. This data set contains results for f...
Long-term effects of mercury in a salt marsh: hysteresis in the distribution of vegetation following recovery from contamination.
Vßlega, M; Lilleb°, A I; Pereira, M E; Duarte, A C; Pardal, M A
During four decades, the Ria de Aveiro was subjected to the loading of mercury from a chlor-alkali industry, resulting in the deposition of several tons of mercury in the sediments. The present study evaluates the impact of this disturbance and the recovery processes, temporally and spatially, by means of examining the richness of the species of salt marsh plants and mercury concentrations in sediments over the last fifty years. The temporal assessment showed that the mercury loading induced a shift in the species composition of the salt marsh from a non-disturbed salt marsh with higher species richness to an alternative state dominated by Phragmites australis. The horizontal assessment, through a mercury gradient, presents the same trend, indicating that P. australis is the species most tolerant to higher mercury concentrations, comparative to Halimione portulacoides, Arthrocnemum fruticosum, Triglochin maritima, Juncus maritimus and Scirpus maritimus. After the reduction of mercury discharges in 1994, the salt marsh shows a slowly return path recovery response. The hysteresis in the response results in the temporal gap between the reduction in mercury concentrations in the sediment and the salt marsh species richness response, comparatively to the existing diversity in the local reference marsh. PMID:18061237
Alterations to Tidal Marsh Carbon Cycling and Greenhouse Gas Exchange in Response to Sea-Level and Salt-Water Intrusion (Invited)
NASA Astrophysics Data System (ADS)
Weston, N. B.
Tidal marshes are highly productive ecosystems with the potential to sequester large amounts of carbon. However, tidal wetlands may be sources of the powerful greenhouse gases (GHGs) methane (CH4) and nitrous oxide (N2O), which are produced via microbial metabolic processes. As global climate changes it is increasingly important to understand the factors that control ecosystem productivity, GHG fluxes, and potential feedbacks between global change factors, C cycling, and marsh resilience to sea-level rise (SLR). Field measurements were undertaken to quantify rates of GHG (CO2 and CH4) exchange rates, plant biomass, microbial sulfate reduction and methanogenesis rates, and soil biogeochemistry at three tidal wetland sites along the salinity gradient in the Delaware River Estuary over four years. Despite similar plant productivity between marsh types, differences in microbial processes largely determined the GHG source/sink status of the wetland types. Mesohaline salt-marshes consistently sequestered C (~300 g C m-2 yr-1), and due to negligible CH4 release, were also a GHG sink (~1350 g CO2-eq m-2 yr-1). In contrast, the TFM sequestered C (~350 g C m-2 yr-1) but because of appreciable release of CH4 from freshwater wetland soils was GHG neutral. The oligohaline marsh site experienced significant seasonal salt-water intrusion (SWI) in the late summer during the four year study period, resulting in major alterations to marsh C cycling. The oligohaline marsh did not sequester C (loss of ~45 g C m-2 yr-1) in part due to surprisingly high rates of CH4 release (190 g CH4 m-2 yr-1). The oligohaline marsh undergoing SWI was therefore a significant source of GHG to the atmosphere (~4000 g CO2-eq m-2 yr-1). These results indicate that SWI alters C cycling and GHG exchange in marsh systems, and may accelerate the decomposition of organic matter limiting the ability of marshes to accrete material and keep pace with SLR. The impacts of SWI on TFM soil C cycling were further investigated in a one year laboratory experiment. Microbial organic matter mineralization to CO2 increased following simulated SWI. This was linked to greater availability of sulfate (SO42-) and higher rates of microbial sulfate reduction, resulting in significantly greater flux of CO2 from TFM soils. Rates of CH4 release were also significantly greater from soils following SWI, and microbial acetoclastic methanogensis was not inhibited by the introduction of salt-water, supporting findings from the field measurements. Higher rates of microbial organic matter mineralization via both sulfate reduction and methanogenesis resulted in declining soil organic matter following SWI. A multi-year field manipulation utilizing modified marsh ';organs' to examine the interactive effects of both SWI and SLR indicated that, while N2O emissions decreased with flooding (-0.3 g m-2 yr-1 cm-1), rates of CH4 flux increased with flooding (2.3 g m-2 yr-1 cm-1) corresponding to measured increases in microbial methanogenesis and resulting in a net increase in GHG release. There were complex interactions between changes in plant production and microbial organic matter decomposition with both SLR and SWI, and TFMs experiencing both SLR and SWI simultaneously had reduced C sequestration and increased GHG release. SLR and SWI therefore limit the vertical accretion potential of TFMs, put TFMs at risk of permanent submergence, and produce a feedback to atmospheric GHG concentrations.
Tracer Analysis of Methanogenesis in Salt Marsh Soils å
King, Gary M.; Wiebe, W. J.
Differences in paths of carbon flow have been found in soils of the tall (TS) and short (SS) Spartina alterniflora marshes of Sapelo Island, Ga. Gaseous end products of [U-14C]glucose metabolism were 14CO2 and 14CH4 in the SS region and primarily 14CO2 in the TS region. Sulfate concentration did not demonstrably affect glucose catabolism or the distribution of end products in either zone. [U-14C]acetate was converted to 14CO2 and 14CH4 in the SS soils and almost exclusively to 14CO2 in the TS soils. Sulfate concentration did not affect acetate metabolism in the SS soils; however, a noticeable effect of sulfate dilution was seen in TS soils. Sulfate dilution in TS samples resulted in increased methane formation. Total glucose and acetate metabolism were similar in TS and SS soils despite differences in end products. A microbial community characterized by fermentative/sulfate-reducing processes has developed in TS soils as opposed to the fermentative/methanogenic/sulfate-reducing community found in SS soils. PMID:16345551
Long-term CH3Br and CH3Cl flux measurements in temperate salt marshes
NASA Astrophysics Data System (ADS)
Blei, E.; Heal, M. R.; Heal, K. V.
Fluxes of CH3Br and CH3Cl and their relationship with potential drivers such as sunlight, temperature and soil moisture, were monitored at fortnightly to monthly intervals for more than two years at two contrasting temperate salt marsh sites in Scotland. Manipulation experiments were conducted to further investigate possible links between drivers and fluxes. Fluxes followed both seasonal and diurnal trends with highest fluxes during summer days and lowest (negative) fluxes during winter nights. Mean (▒ 1 sd) annually and diurnally-weighted net emissions from the two sites were found to be 300 ▒ 44 ng m-2 h-1 for CH3Br and 662 ▒ 266 ng m-2 h-1 for CH3Cl. The fluxes from this work are similar to findings from this and other research groups for salt marshes in cooler, higher latitude climates, but lower than values from salt marshes in the Mediterranean climate of southern California. Statistical analysis generally did not demonstrate a strong link between temperature or sunlight levels and methyl halide fluxes, although it is likely that temperatures have a weak direct influence on emissions, and both certainly have indirect influence via the annual and daily cycles of the vegetation. CH3Cl flux magnitudes from different measurement locations depended on the plant species enclosed whereas such dependency was not discernible for CH3Br fluxes. In 14 out of 18 collars with vegetation CH3Br and CH3Cl net fluxes were significantly positively correlated. The CH3Cl/CH3Br net-emission mass ratio was 2.2, a magnitude lower than mass ratios of global methyl halide budgets (~22) or emissions from tropical rainforests (~60). This is likely due to preference for CH3Br production by the relatively high bromine content in the salt marsh plant material. Extrapolation based solely on data from this study yields salt marsh contributions of 0.5-3.2% and 0.05-0.33%, respectively, of currently-estimated total global production of CH3Br and CH3Cl, but actual global contributions likely lie between these values and those derived from southern California.
C3\\/C4 variations in salt-marsh sediments: An application of compound specific isotopic analysis of lipid biomarkers to late Holocene paleoenvironmental research
Benjamin R. Tanner; Maria E. Uhle; Joseph T. Kelley; Claudia I. Mora
In salt-marshes, bulk carbon isotope values reflect organic matter contributions not only from salt-marsh plants, but also from algal and bacterial inputs, as well as allochthonous terrestrial organic matter. In the present study, compound specific isotope analysis was applied to a core and modern plant samples collected from a Machiasport, Maine salt-marsh. We sampled 10 plant species common to the
Environmental limitations on recruitment from seed in invasive Spartina densiflora on a southern European salt marsh
NASA Astrophysics Data System (ADS)
Mateos-Naranjo, Enrique; Redondo-G¾mez, Susana; Luque, Carlos J.; Castellanos, Eloy M.; Davy, Anthony J.; Figueroa, M. Enrique
The South American cordgrass, Spartina densiflora, has invaded a range of different habitats that can support different native species assemblages on salt marshes in the Gulf of Cadiz, Spain. Little is known about the mechanisms of invasion. We examined the potential for seed germination and recruitment in a field transplant experiment, representing a wide range of environments, on elevational gradients across marshes with muddy and sandy sediments. The biotic resistance of native, perennial vegetation (where present) to recruitment of the alien was also investigated. Spartina densiflora seeds were able to germinate over a greater than 2-m range of elevation in the tidal frame. Germination success on unvegetated muddy sediments was related to sediment redox potential, with poor germination at strongly negative redox potentials on the lower sites. On sandy, well-drained sediments, germination was apparently constrained by water availability at the highest elevations. Comparison of vegetated and cleared plots on the upper marsh showed that there was a negative relationship between the presence of Atriplex portulacoides and germination on the muddy sediments. Recruitment (survival of seedlings for 12 weeks) was seen only on unvegetated muddy sediments at the highest elevation. Hence the invasive success and wide elevational tolerance of S. densiflora on the marshes of the Gulf of Cadiz are not reflected in its short-term ability to become established from its prolific seed production. Colonization of sub-optimal habitats may be largely by vegetative propagules and clonal growth.
Potential uses of TerraSAR-X for mapping herbaceous halophytes over salt marsh and tidal flats
NASA Astrophysics Data System (ADS)
Lee, Yoon-Kyung; Park, Jeong-Won; Choi, Jong-Kuk; Oh, Yisok; Won, Joong-Sun
This study presents a method and application results of mapping different halophytes over tidal flats and salt marshes using high resolution space-borne X-band synthetic aperture radar (SAR) that has been rarely used for salt marsh mapping. Halophytes in a salt marshes are sensitive to sea-level changes, sedimentation, and anthropogenic modifications. The alteration of the demarcations among halophyte species is an indicator of sea level and environmental changes within a salt marsh. The boundary of an herbaceous halophyte patch is, however, difficult to determine using remotely sensed data because of its sparseness. We examined the ecological status of the halophytes and their distribution changes using TerraSAR-X and optical data. We also determined the optimum season for halophyte mapping. An annual plant, Suaeda japonica (S. japonica), and a typical perennial salt marsh grass, Phragmites australis (P. australis), were selected for halophyte analysis. S. japonica is particularly sensitive to sea level fluctuation. Seasonal variation for the annual plant was more significant (1.47 dB standard deviation) than that for the perennial grass, with a pattern of lower backscattering in winter and a peak in the summer. The border between S. japonica and P. australis was successfully determined based on the distinctive X-band radar backscattering features. Winter is the best season to distinguish between the two different species, while summer is ideal for analyzing the distribution changes of annual plants in salt marshes. For a single polarization, we recommend using HH polarization, because it produces maximum backscattering on tidal flats and salt marshes. Our results show that high resolution SAR, such as TerraSAR-X and Cosmo-SkyMed, is an effective tool for mapping halophyte species in tidal flats and monitoring their seasonal variations.
Magnitudes and spatial and temporal patterns of self-organized processes between geomorphology and biota that drive salt marsh evolution
NASA Astrophysics Data System (ADS)
Cornacchia, L.; Taramelli, A.; Valentini, E.; Monbaliu, J. A.; Sabbe, K.
Many complex systems show non-equilibrium fluctuations, often determining the spontaneous evolution towards a critical state. In this context salt marshes are known to be characterized by complex patterns in both geomorphological and ecological features, which often appear to be strongly correlated. One of the main drivers on low-order channel network geometry is the hydrodynamic forcing entering the system in the form of an intermittent stress: the occurrence of infrequent rainfall events determines saturation-excess overland flow, which results in higher stream energy to be dissipated through an increase in cross section and meandering of the tidal channels in the marsh. This external driver determines a second, important effect on the intertidal zone: together with the emergence of a higher number of minor draining channels, salt marshes are provided with pulses of sediment input, causing a vertical build-up that allows pioneer species to colonize new areas of mudflat and channels. This eventually leads to salt marsh development through the higher frequency of occurrence and horizontal spread of marsh pioneer patterns, coupled with the displacement of the limit between the salt marsh and mudflat. As opposed to infrequent events, a much more frequent source of variation and uncertainty affecting the system is the difference between the observed and astronomical tide, which is referred to as surge. Since it would be difficult to simultaneously monitor these parameters through field surveys, and even harder to analyze them over medium to large time scales, we propose a remote sensing approach to monitor the temporal dynamics of both biotic and abiotic factors in salt marshes. We characterized the complex interactions between morphology and biota in two salt marshes in the densely populated Scheldt estuary through the implementation of different algorithms on multispectral endmember fraction maps from optical space-borne remote sensing. Multitemporal fractional abundance maps spanning from 1986 to 2011 were used to identify the interaction between vegetation pattern dynamics and channel drainage density, and integrated with field sampling and in situ spectroradiometry. The objectives were to: a) analyze and validate the processing procedure used to define the patterns of macrophyte vegetation cover; b) obtain field data on microphytobenthos biomass in two intertidal mudflat areas differing in the degree of sediment cohesiveness; c) integrate spectroradiometric measurements with simultaneous sampling; d) build a spectral library of salt marsh vegetation composition and zonation of Northern Europe estuarine areas. The latter can then be compared with vegetation field sampling data already available on the Plymouth estuary, Po Delta and Venice lagoon, in order to support the classification of the different surface cover types for the development of new methods of monitoring salt marsh-mudflat systems.
Salt marsh retreat induced by wind waves: experiments, field and modeling
NASA Astrophysics Data System (ADS)
Solari, L.; Francalanci, S.; Bendoni, M.; Cappietti, L.
Edge erosion of salt marshes due to surface waves and tide forcing is likely the chief mechanism that models marsh boundaries and by which salt marshes in worldwide areas are being lost. To address this problem, an experimental investigation in a laboratory flume and field measurements collected in the lagoon of Venice were conducted to understand the main processes controlling marsh edge retreat with a focus on the erosion mechanisms caused by the impact of wind waves in the case of various tidal levels. A physical model reproducing a salt marsh bank was built inside a long wave current flume where random surface waves have been generated according to a given wave spectrum. The physical model was constructed with the original soil of salt marshes from the Venice Lagoon, while the wave climate was reproduced according to field measurements. In order to reveal the effect of vegetation on bank stability, two identical banks were built but for the inclusion of halophytic plants. A first set of experiments was conducted reproducing only tidal waves, a second set with wind waves superimposed to the tide. A third set o f experiments were aimed to investigate the dynamic impact and transmission of the waves on and within the bank. The following quantities were collected during the experiments: water content and pore water pressure inside the bank, water levels and velocities at various distances from the bank, dynamic pressures on the bank edge surface and internal pressure fluctuations due to wave impact. Bank geometry profile and bottom topography at different times have also been collected to characterize the erosion rate with time and the evolution of bank retreat. Two types of mass failures were observed during the experiments: slides and toppling failures. The latter were most frequently observed failures, consisting in the toppling of blocks and were often the consequence of the presence of deep tension cracks. In most cases the impact of wind waves caused the overturning of the block. In both the unvegetated and vegetated experiments, mass failures occurred in the first part of the experiment whereas the remaining part was characterized by particle by particle erosion. Effect of vegetation lead to a delay in block failures due the presence of roots, although the total eroded volume differed slightly between the two scenarios. The field measurements were aimed at quantifying the erosion characteristics of marsh soil and the wave climate close to the bank edge during a moderate wind event. Several pressure transducers installed 0.15 m above the bed and adequately spaced were used to collect wave height and wave direction with respect to the edge of the marsh. Then, on the base of experimental and field evidence, a new toppling model is proposed and test against laboratory data: a block of cohesive material at incipient failing condition is attached to the underlying layer and identified by the presence of tension crack; it behaves as a dynamical system subjected to several forces, until the tensile strength of the material is exceed. Test of the model showed its capability at reproducing the failure process and it highlighted which are the most crucial conditions in promoting the failure of a bank edge subjected to wave attack and tide forcing.
Alteration of a Salt Marsh Bacterial Community by Fertilization with Sewage Sludge
Hamlett, Nancy V.
The effects of long-term fertilization with sewage sludge on the aerobic, chemoheterotrophic portion of a salt marsh bacterial community were examined. The study site in the Great Sippewissett Marsh, Cape Cod, Mass., consisted of experimental plots that were treated with different amounts of commercial sewage sludge fertilizer or with urea and phosphate. The number of CFUs, percentage of mercury- and cadmium-resistant bacteria, and percentage of antibiotic-resistant bacteria were all increased in the sludge-fertilized plots. Preliminary taxonomic characterization showed that sludge fertilization markedly altered the taxonomic distribution and reduced diversity within both the total heterotrophic and the mercury-resistant communities. In control plots, the total heterotrophic community was fairly evenly distributed among taxa and the mercury-resistant community was dominated by Pseudomonas spp. In sludge-fertilized plots, both the total and mercury-resistant communities were dominated by a single Cytophaga sp. PMID:16347183
Multitemporal spectroradiometry-guided object-oriented classification of salt marsh vegetation
NASA Astrophysics Data System (ADS)
Civco, Daniel L.; Gilmore, Martha S.; Wilson, Emily H.; Barrett, Nels; Prisloe, Sandy; Hurd, James D.; Chadwick, Cary
This study addresses the use of multitemporal field spectral data, satellite imagery, and LiDAR top of canopy data to classify and map common salt marsh plant communities. Visible to near-infrared (VNIR) reflectance spectra were measured in the field to assess the phenological variability of the dominant species - Spartina patens, Phragmites australis and Typha spp. The field spectra and single date LiDAR canopy height data were used to define an objectoriented classification methodology for the plant communities in multitemporal QuickBird imagery. The classification was validated using an extensive field inventory of marsh species. Overall classification accuracies were 97% for Phragmites, 63% for Typha spp. and 80% for S. patens meadows. Using a fuzzy assessment analysis, these accuracies were 97%, 76%, and 92%, respectively, for the three major species.
Mobility of Pb in salt marshes recorded by total content and stable isotopic signature.
Caetano, Miguel; Fonseca, Nuno; Cesßrio Carlos Vale, Rute
Total lead and its stable isotopes were analysed in sediment cores, leaves, stem and roots of Sacorconia fruticosa and Spartina maritima sampled from Tagus (contaminated site) and Guadiana (low anthropogenic pressure) salt marshes. Lead concentration in vegetated sediments from the Tagus marsh largely exceeded the levels in non-vegetated sediments. Depth profiles of (206)Pb/(207)Pb and (206)Pb/(208)Pb showed a decrease towards the surface ((206)Pb/(207)Pb=1.160-1.167) as a result of a higher proportion of pollutant Pb components. In contrast, sediments from Guadiana marsh exhibited low Pb concentrations and an uniform isotopic signature ((206)Pb/(207)Pb=1.172+/-0.003) with depth. This suggests a homogeneous mixing of mine-derived particles and pre-industrial sediments with minor inputs of anthropogenic Pb. Lead concentrations in roots of plants from the two marshes were higher than in leaves and stems, indicating limited transfer of Pb to aerial parts. A similar Pb isotopic signature was found in roots and in vegetated sediments, indicating that Pb uptake by plants reflects the input in sediments as determined by a significant anthropogenic contribution of Pb at Tagus and by mineralogical Pb phases at Guadiana. The accumulation in roots from Tagus marsh (max. 2870 microg g(-1) in S. fruticosa and max. 1755 microg g(-1) in S. maritima) clearly points to the dominant role of belowground biomass in the cycling of anthropogenic Pb. The fraction of anthropogenic Pb in belowground biomass was estimated based on the signature of anthropogenic Pb components in sediments ((206)Pb/(207)Pb=1.154). Since no differences exist between Pb signature in roots and upper sediments, the background and anthropogenic levels of Pb in roots were estimated. Interestingly, both background and anthropogenic Pb in roots exhibited a maximum at the same depth, although the proportion of anthropogenic Pb was relatively constant with depth (83+/-4% for S. fruticosa and 74+/-8% for S. maritima). PMID:17320933
Mercury accumulation in largemouth bass (Micropterus salmoides LacķpĶde) within marsh ecosystems of the Florida Everglades, USA.
Julian, Paul; Gu, Binhe
This study evaluates factors, particularly water quality related, that may influence mercury (Hg) bioaccumulation in largemouth bass (LMB, Micropterus salmoides LacķpĶde) within the Everglades marshes of South Florida. The investigation is an empirical analysis of ambient data from both long-term fish monitoring and marsh water quality monitoring sites across the Everglades Protection Area. Previous Hg studies of Everglade's marsh biota have focused on the role that sulfate plays in Hg bioaccumulation. While sulfate can be important under some environmental conditions, this empirical analysis in Everglades marshes showed that sulfate has little association with Hg concentrations in LMB. It is suggested that other water quality variables including water pH, alkalinity and specific conductance may have as much or more influence in the accumulation of Hg in LMB. Furthermore, tissue Hg concentration normalized to body-weight and age-specific growth rates were significantly correlated with Water Conservation Area (WCA)-1, WCA-2 and Everglades National Park (ENP) but not WCA-3. However, body condition was correlated negatively with Hg concentration only within WCA-2, WCA-3 and ENP; the relationship was not significant within WCA-1. This disparity between Hg concentration and body condition could be attributed to ecological effects including water quality and quantity conditions within each compartment of the system that are significant driving forces for biota abundance, trophic structure and distribution within the Everglades ecosystem. While water quality and quantity are important, trophic position of LMB has the potential to influence Hg accumulation dynamics. In spite of documented biogeochemical linkages to Hg accumulation, this empirical analysis did not demonstrate enough quantitative interaction to be useful for Hg management in the Everglades ecosystem. PMID:25336046
The Life Cycle of Entzia, an Agglutinated Foraminifer from the Salt Marshes in Transylvania
NASA Astrophysics Data System (ADS)
Kaminski, Michael; Telespan, Andreea; Balc, Ramona; Filipescu, Sorin; Varga, Ildiko; G÷r÷g, Agnes
The small salt marshes associated with Miocene salt domes in Transylvania are host to a variety of marine organisms, including communities of halophytic plants as well as an agglutinated foraminifer that is normally found in coastal salt marshes worldwide. Originally described as the species Entzia tetrastoma by Daday (1884), the foraminifer is more widely known by the name Jadammina macrescens (Brady, 1870). Because the genus name Entzia has priority over Jadammina, the valid name of this taxon is Entzia macrescens (Brady, 1870). In 2007, we discovered a living population of Entzia inhabiting a small salt marsh just outside the town of Turda in central Transylvania, only a kilometer from the famous Maria Theresa Salt Mine. This is the first discovery of a living population of Entzia in Transylvania since the species was originally described in 1884. To determine whether or not the specimens we found represent a breeding population, samples were collected from the marsh on a monthly basis over the span of a year. This species can be found among the roots of the halophytic plants, in the uppermost one or two centimeters of the mud. Sediment samples were preserved in Vodka with Rose Bengal to distinguish living and dead specimens, and examined quantitatively. To document the life cycle of the species the following metrics were carried out: test size, abundance, number of chambers, ratio between live and dead specimens, and the diameter of the proloculus. An increase in the mean diameter of specimens was found from October to December. However the mean diameter decreased again in January, which suggests that asexual reproduction had apparently taken place. Small specimens again appeared in March, when sexual reproduction is presumed to have taken place. The median proloculus diameter was smallest in April and May, but the monthly changes in mean proloculus size within the population over the span of a year are not significant. However, specimens with largest proloculus diameters (up to 50 microns) are found in winter, and specimens with smallest proloculi (11 microns) are found in spring. In this respect, the life cycle of Entzia macrescens resembles that of the well-known invasive species Trochammina hadai. We are taking measures to preserve the site containing the living Entzia population, as the area is located opposite a public swimming pool and is endangered by human activity.
A multi-proxy study of sedimentary humic substances in the salt marsh of the Changjiang Estuary, China
NASA Astrophysics Data System (ADS)
Zhang, Yaoling; Du, Jinzhou; Zhao, Xin; Wu, Wangsuo; Peng, Bo; Zhang, Jing
To better understand the origin, composition, and reactivity of sedimentary humic substances (HSs) in salt marshes in the Changjiang Estuary, HS samples were isolated from a sediment core that was collected from the Eastern Chongming salt marsh. Chemical and spectroscopic methods were used to analyze the features of these HSs. The results indicate that the studied HSs in the salt marsh sediments are mainly terrestrial-derived and that the sedimentary organic matter (SOM) in the top layer may contain more organic matter from marine sources and/or autochthonous materials due to the dramatic decreasing of the sediment supply as a result of damming. The degradation of labile carbohydrates and proteins and the preservation of refractory lignin components dominate the early diagenetic reactions of SOM in the salt marsh area. The average contents of the carboxylic groups in FAs and HAs are 11.64Ā▒Ā1.08 and 7.13Ā▒Ā0.16Āmeq/gC, and those of phenolic groups are 1.95Ā▒Ā0.13 and 2.40Ā▒Ā0.44Āmeq/gC, respectively. The content of carboxylic groups increased with increasing depth, while there were no obvious changes in the content of phenolic groups. The average concentration of total proton-binding sites is approximately 12.5Ā?mol/g sediment for the studied HSs. These values may provide insight into the migration and fate of HS-bound contaminants in sediments and the overlying sea water in the salt marsh areas of the Changjiang Estuary.
Accumulation of plant nutrients and heavy metals through sedimentation processes and accretion in a Louisiana salt marsh
R. D. DeLaune; C. N. Reddy; W. H. Patrick
The accumulation of selected plant nutrients and heavy metals in a rapidly accreting Louisiana salt marsh was examined. Sedimentation\\u000a processes were shown to be supplying large amounts of plant nutrients to the marsh. Accumulation of heavy metals was low and\\u000a appeared to be associated with the natural heavy metal content of incoming sediment rather than from a pollution source. A
Sediment transport in a cold climate salt marsh (St. Lawrence Estuary, Canada), the importance of vegetation and waves
NASA Astrophysics Data System (ADS)
Coulombier, Thibault; Neumeier, Urs; Bernatchez, Pascal
Salt marshes in the St. Lawrence Estuary are subjected to strong seasonal variations with sub-arctic winter conditions. The present paper explores sedimentary processes in the Pointe-aux-╔pinettes marsh during the ice-free period. Currents, waves, suspended sediment, and sedimentation rates have been measured in June, August and October 2009. Vegetation growth was monitored during one year on a monthly basis to understand the seasonal impact on the marsh. Vegetation attenuates currents and waves, but this attenuation changes over the year as vegetation disappears along winter. Results show that suspended sediment transport and deposition are controlled by vegetation, wave height, currents, distance from the marsh edge and distance from sediment sources. Suspended sediment concentrations and sedimentation rates were significantly correlated to wave height, highlighting the importance of waves for sediment resuspension transport. Transport was lowest in August when vegetation was high and wave occurrence low. However, vegetation growth didn't change fundamentally sediments dynamic of the marsh. Within one tide, an important part of sediment transport is only local within the marsh, as shown by the maximum sedimentation rates occurring near unvegetated areas of the marsh. Data provide a spatial understanding of summer sedimentology on cold climate marshes.
Studies on the production and decomposition of Spartina alterniflora Loisel. in a Galveston salt marsh
Sears, Norman Evans
and Atlantic coasts. Page 2 Galveston Tides, 1979 ' 13 3 Paired t-test showing the differences between standing crops at the beginning and at the end of sampling . . . . . . 31 4 Smalley method estimate of net aerial production 5a Litter bag loss rates... (from clipped samples) 55 viii LIST OF FIGURES 1 Watershed of Galveston Bay 2 Galveston Island, West Bay, and surrounding salt marshes . . 16 3' Location of study area on Galveston Island 4a method of finding leaf area lost 4b Alternative method...
Patterns in tidal environments: salt-marsh channel networks and vegetation
NASA Astrophysics Data System (ADS)
Marani, M.; Silvestri, S.; Belluco, E.; Camuffo, M.; D'Alpaos, A.; Lanzoni, S.; Marani, A.; Rinaldo, A.
Salt marshes in tidal environments are characterised by complex patterns both in their geomorphic and ecological features. Such patterns arise through the elaboration of a network structure driven by the tidal forcing and through the interaction between hydrodynamical, geophysical and ecological components (e.g. microphytobenthos and vegetation). This contribution introduces observations of tidal environments from remote sensing and ancillary data collected in the field. In particular CASI, MIVIS and LiDar airborne data and IKONOS and Quick-Bird satellite data on the lagoon of Venice (Italy) have been acquired in the period 2001-2002Salt marshes in tidal environments are characterised by complex patterns both in their geomorphic and ecological features. Such patterns arise through the elaboration of a network structure driven by the tidal forcing and through the interaction between hydrodynamical, geophysical and ecological components (e.g. microphytobenthos and vegetation). This contribution introduces observations of tidal environments from remote sensing and ancillary data collected in the field. In particular CASI, MIVIS and LiDar airborne data and IKONOS and Quick-Bird satellite data on the lagoon of Venice (Italy) have been acquired in the period 2001-2002, within the European RTD project TIDE. The remotely sensed data have been radiometrically calibrated, atmospherically corrected and accurately georeferenced to allow the comparison with ground truth observations. Classification and unmixing techniques are then used to derive the spatial distribution of salt marsh vegetation species, which are also characterised through the use of vegetation indexes (e.g. NDVI), allowing an objective and quantitative analysis of vegetation patterns. The set of observations available are further used, together with mathematical models, to describe channel meandering characteristics and branching properties yielding an accurate and spatially distributed description of the tidal network. . The remotely sensed data have been radiometrically calibrated, atmospherically corrected and accurately georeferenced to allow the comparison with ground truth observations. Classification and unmixing techniques are then used to derive the spatial distribution of salt marsh vegetation species, which are also characterised through the use of vegetation indexes (e.g. NDVI), allowing an objective and quantitative analysis of vegetation patterns. The set of observations available are further used, together with mathematical models, to describe channel meandering characteristics and branching properties yielding an accurate and spatially distributed description of the tidal network.
The Protective Role of Coastal Marshes: A Systematic Review and Meta-analysis
Christine C. Shepard; Caitlin M. Crain; Michael W. Beck
BackgroundSalt marshes lie between many human communities and the coast and have been presumed to protect these communities from coastal hazards by providing important ecosystem services. However, previous characterizations of these ecosystem services have typically been based on a small number of historical studies, and the consistency and extent to which marshes provide these services has not been investigated. Here,
Suspended sediment deposition and trapping efficiency in a Delaware salt marsh
NASA Astrophysics Data System (ADS)
Moskalski, Susanne M.; Sommerfield, Christopher K.
This study examined sediment deposition and retention in a section of salt marsh in the St. Jones River estuary in Delaware. Sediment traps, siphon samplers, a LISST particle sizer, and four water level sensors were deployed in a 100 m by 200 m grid over the course of a spring tide in June 2007. The objective was to determine the relative influences of suspended sediment concentration, settling velocity, tidal hydroperiod, and vegetation density on sediment deposition and trapping efficiency within a small section of marsh. Hydroperiod is not a major contributor to sediment deposition in the study plot. Spatial patterns in depositional processes on tidal timescales are instead primarily controlled by overmarsh SSC, settling velocity, and distance from the tidal channel. Trapping efficiency, or the ratio of measured deposition and the amount of sediment available for deposition, decreased with distance away from the tidal channel, indicating that less of the available suspended sediment was deposited in the marsh interior. The suspended particles were flocculated, but floc sizes decreased with distance away from the tidal channel.
Effects of Natural and Anthropogenic Change on Habitat Use and Movement of Endangered Salt Marsh Harvest Mice
Smith, Katherine R.; Barthman-Thompson, Laureen; Gould, William R.; Mabry, Karen E.
The northern salt marsh harvest mouse (Reithrodontomys raviventris halicoetes) is an endangered species endemic to the San Francisco Bay Estuary. Using a conservation behavior perspective, we examined how salt marsh harvest mice cope with both natural (daily tidal fluctuations) and anthropogenic (modification of tidal regime) changes in natural tidal wetlands and human-created diked wetlands, and investigated the role of behavioral flexibility in utilizing a human-created environment in the Suisun Marsh. We used radio telemetry to determine refuge use at high tide, space use, and movement rates to investigate possible differences in movement behavior in tidal versus diked wetlands. We found that the vast majority of the time salt marsh harvest mice remain in vegetation above the water during high tides. We also found no difference in space used by mice during high tide as compared to before or after high tide in either tidal or diked wetlands. We found no detectable difference in diurnal or nocturnal movement rates in tidal wetlands. However, we did find that diurnal movement rates for mice in diked wetlands were lower than nocturnal movement rates, especially during the new moon. This change in movement behavior in a relatively novel human-created habitat indicates that behavioral flexibility may facilitate the use of human-created environments by salt marsh harvest mice. PMID:25310800
Effects of Adding Sewage Sludge and Urea-Phosphate Fertilizers to the Great Sippewissett Salt Marsh, Falmouth, MA on Heavy Metals and Microbial N-Cycling
Vallino, Joseph J.
Effects of Adding Sewage Sludge and Urea-Phosphate Fertilizers to the Great Sippewissett Salt Marsh, microbes, nitrogen cycle, sewage sludge, urea phosphate fertilizer, heavy metals INTRODUCTION Pollution of nitrogen gas in the atmosphere. Salt marshes have been used as disposal sites because they act as filters
Variation in nutrient availability and plant species diversity across forb and graminoid zones of a Northern New England high salt marsh
Theresa A. Theodose; Justine B. Roths
Plant zonation patterns across New England salt marshes have been investigated for years, but how nutrient availability differs between zones has received little attention. We investigated how N availability, P availability, and plant N status varied across Juncus gerardii, Spartina patens, and mixed forb zones of a Northern New England high salt marsh. We also investigated relationships between several edaphic
Salt-marsh geomorphological patterns analysis based on remote sensing images and lidar-derived digital elevation model: a case study of Xiaoyangkou, Jiangsu
Yan Xie; Xiaoxiang Zhang; Xianrong Ding; Siqi Liu; Changkuan Zhang
It is very difficult to perform geomorphological analyses and modeling in the salt marshes because of fieldwork logistics, the tidal oscillation and variability, and the inherent dynamic nature of these environments. Recently novel technologies and methods introduce the capability to create high-resolution biophysical and elevation databases to quantitatively characterize salt marsh geomorphology in support of improved understanding of the evolution
Spectroscopic properties of sedimentary humic acids from a salt marsh (Ria de Aveiro, Portugal): comparison of sediments colonized by Halimione portulacoides (L.) Aellen and non-vegetated sediments
Ana Mendonńa; Armando C. Duarte; Eduarda B. H. Santos
The influence of the colonization of salt marsh sediments with Halimione portulacoides, on the composition of the sedimentary humic acids was evaluated. For this purpose, cores of colonized and non-colonized sediments from a salt marsh in Ria de Aveiro (Portugal) were collected, and the humic acids of different layers were extracted and characterized by Fourier transform infrared, synchronous molecular fluorescence
Bermingham, Eldredge
SYMBIOSIS BETWEEN AN ALPHEID SHRIMP AND A XANTHOID CRAB IN SALT MARSHES OF MID-ATLANTIC STATES, U snapping shrimp (Alpheus heterochaelis) participates in a symbiosis with the black-clawed mud crab.S.A. We surveyed eight mid-Atlantic salt marshes and found that 11% of occupied crab burrows (n ╝ 1042
Ecosystem response to changes in water level of Lake Ontario marshes: lessons from the restoration of Cootes Paradise Marsh
Patricia Chow-Fraser
A general understanding of how aquatic vegetation responds to water-level fluctuations is needed to guide restoration of Great Lakes coastal wetlands because inter-annual and seasonal variations often confound effects of costly remedial actions. In 1997, common carp (Cyprinus carpio) was removed from Cootes Paradise Marsh (L. Ontario) to reduce sediment resuspension and bioturbation, and thus regenerate marsh plants that had
Vegetation dynamics and plant species interactions under grazed and ungrazed conditions in a western European salt marsh
NASA Astrophysics Data System (ADS)
Tessier, Marc; Vivier, Jean-Paul; Ouin, Annie; Gloaguen, Jean-Claude; Lefeuvre, Jean-Claude
Experiments in exclosures were conducted on a salt marsh in a macrotidal system in western France. The aim of this study was threefold: (1) to compare vegetation dynamics over a period of 8 years in grazed and ungrazed conditions (2) to investigate the response of annual species to grazing duration during seedling establishment (3) to test the effect of an increase in soil nitrogen availability after cessation of grazing on interactions between Suaeda maritima and Puccinellia maritima. In grazed conditions, during all the survey, vegetation was dominated by a short P. maritima sward with the annual Salicornia europaea in the lower and middle marshes. However, after cessation of grazing in 1994, a homogeneous matrix of the forb Halimione portulacoides, quickly replaced P. maritima in the well drained lower marsh. At the middle marsh level, fine sediment and poor drainage maintained P. maritima while the annual S. maritima which tolerates taller and denser vegetation replaced S. europaea. Elymus pungens cover was limited till 2000 but its rising in 2001 let expect its dominance in the future. While P. maritima abundance remained high, spring abundance of annual species such as S. europaea and S. maritima globally decreased with sheep grazing duration on the salt marsh between February and June. Experiments with monocultures of P. maritima and S. maritima demonstrated that nitrogen was a limiting factor on the salt marsh. In a mixed community, a moderate application of nitrogen (15 g N m -2 year -1 as NH 4-NO 3) promoted growth of P. maritima and limited the biomass of S. maritima, but growth of the latter was enhanced by a high application of nitrogen (30 g N m -2 year -1). An increase in the abundance of annuals such as S. maritima on the salt marsh is discussed.
Macroinvertebrate and fish populations in a restored impounded salt marsh 21 years after the reestablishment of tidal flooding.
Swamy, Varun; Fell, Paul E; Body, Misha; Keaney, Michael B; Nyaku, Mawuli K; McIlvain, Elizabeth C; Keen, Alice L
During the last two decades, the State of Connecticut has restored tidal flow to many impounded salt marshes. One of the first of these and the one most extensively studied is Impoundment One in the Barn Island Wildlife Management Area in Stonington, Connecticut. In 1990, twelve years after the re-establishment of tidal flooding, the density of the marsh snail Melampus bidentatus, the numerically dominant macroinvertebrate of the high marsh, in Impoundment One was about half that in reference marshes below the breached impoundment dike. By 1999 the densities of Melampus above and below the dike were not significantly different, but the shell-free biomass was greater above the dike as a result of the somewhat larger number and size of the snails there. Twenty-one years after the renewal of tidal flooding, three marsh macroinvertebrates (the amphipods Orchestia grillus and Uhlorchestia spartinophila and the mussel Geukensia demissa) were significantly less abundant in the previously impounded marsh than in the reference marshes, whereas another amphipod (Gammarus palustris) was more abundant above the breached dike where conditions appeared to be somewhat wetter. In 1991 the fish assemblage in a mosquito-control ditch in Impoundment One was similar to that in a ditch below the breached dike; however, the common mummichog Fundulus heteroclitus appeared to be less abundant in the restoring marsh. By 1999 the number of mummichogs caught in ditches was significantly greater in Impoundment One than in the reference marsh, but the numbers of mummichogs trapped along the tidal creek were comparable above and below the dike. The results obtained in this study and those of other restoring marshes at Barn Island indicate the full recovery of certain animal populations following the reintroduction of tidal flow to impounded marshes may require up to two or more decades. Furthermore, not only do different species recover at different rates on a single marsh, but the time required for the recovery of a particular species may vary widely from marsh to marsh, often independently of other species. PMID:12071502
Seasonal variability of diazotroph assemblages associated with the rhizosphere of the salt marsh cordgrass, Spartina alterniflora.
Gamble, Megan D; Bagwell, Christopher E; LaRocque, Jeannine; Bergholz, Peter W; Lovell, Charles R
Nitrogen fixation is the primary N source in the highly productive but N-limited North Inlet, SC, USA salt marsh system. The diverse assemblages of nitrogen-fixing (diazotrophic) bacteria associated with the rhizospheres of the short and tall growth forms of Spartina alterniflora were analyzed at two sites, Crab Haul Creek and Goat Island, which are in different tidal creek drainage systems in this marsh. The sites differed in proximity to the main channel for tidal intrusion and in several edaphic parameters. We hypothesized that either the differing abiotic environmental regimes of the two sites or the variation due to seasonal effects result in differences in the diazotroph assemblage. Rhizosphere samples were collected seasonally during 1999 and 2000. DNA was purified and nifH amplified for denaturing gradient gel electrophoresis (DGGE) analysis of diazotroph assemblage composition. Principal components analysis was used to analyze the binary DGGE band position data. Season strongly influenced assemblage composition and biplots were used to identify bands that significantly affected the seasonal and site-specific clustering. The types of organisms that were most responsive to seasonal or site variability were identified on the basis of DGGE band sequences. Seasonally responsive members of the anaerobic diazotrophs were detected during the winter and postsenescence conditions and may have been responsible for elevated pore water sulfide concentrations. Sequences from a diverse assemblage of Gammaproteobacteria were predominant during growth periods of S. alterniflora. Abiotic environmental parameters strongly influenced both the S. alterniflora and the diazotrophic bacterial assemblages associated with this keystone salt marsh plant species. PMID:19626265
Physical Stress, Not Biotic Interactions, Preclude an Invasive Grass from Establishing in Forb-Dominated Salt Marshes
He, Qiang; Cui, Baoshan; An, Yuan
Background Biological invasions have become the focus of considerable concern and ecological research, yet the relative importance of abiotic and biotic factors in controlling the invasibility of habitats to exotic species is not well understood. Spartina species are highly invasive plants in coastal wetlands; however, studies on the factors that control the success or failure of Spartina invasions across multiple habitat types are rare and inconclusive. Methodology and Principal Findings We examined the roles of physical stress and plant interactions in mediating the establishment of the smooth cordgrass, Spartina alterniflora, in a variety of coastal habitats in northern China. Field transplant experiments showed that cordgrass can invade mudflats and low estuarine marshes with low salinity and frequent flooding, but cannot survive in salt marshes and high estuarine marshes with hypersaline soils and infrequent flooding. The dominant native plant Suaeda salsa had neither competitive nor facilitative effects on cordgrass. A common garden experiment revealed that cordgrass performed significantly better when flooded every other day than when flooded weekly. These results suggest that physical stress rather than plant interactions limits cordgrass invasions in northern China. Conclusions and Significance We conclude that Spartina invasions are likely to be constrained to tidal flats and low estuarine marshes in the Yellow River Delta. Due to harsh physical conditions, salt marshes and high estuarine marshes are unlikely to be invaded. These findings have implications for understanding Spartina invasions in northern China and on other coasts with similar biotic and abiotic environments. PMID:22432003
Physiological Diversity of the Rhizosphere Diazotroph Assemblages of Selected Salt Marsh Grasses
Bagwell, Christopher E.; Piceno, Yvette M.; Ashburne-Lucas, Amy; Lovell, Charles R.
Rhizosphere diazotroph assemblages of salt marsh grasses are thought to be influenced by host plant species and by a number of porewater geochemical parameters. Several geochemical variables can adversely affect plant productivity and spatial distributions, resulting in strong zonation of plant species and growth forms. This geochemically induced stress may also influence the species compositions and distributions of rhizosphere diazotroph assemblages, but little is currently known about these organisms. The diversity and key physiological features of culturable, O2-tolerant rhizosphere diazotrophs associated with the tall and short growth forms of Spartina alterniflora and with Juncus roemerianus were examined. A total of 339 gram-negative strains were isolated by a root stab culture approach and morphologically and physiologically characterized by using API and BIOLOG tests. Eighty-six distinct groups composed of physiologically similar strains were identified. Of these groups, 72% were shown to be capable of N2 fixation through molecular analyses, and a representative strain was chosen from each diazotroph group for further characterization. Cluster and principal-components analysis of BIOLOG data allowed the designation of physiologically distinct strain groupings. Most of these groups were dominated by strains that were not identifiable to species on the basis of API or BIOLOG testing. Representatives of several families including the Enterobacteriaceae, Vibrionaceae, Azotobacteraceae, Spirillaceae, Pseudomonadaceae, and Rhizobiaceae were recovered, as well as strains with no clear taxonomic affiliations. This study identifies numerous potentially important physiological groups of the salt marsh diazotroph assemblage. PMID:9797277
Effects of monospecific banks of salt marsh vegetation on sediment bacterial communities.
Oliveira, Vanessa; Santos, Ana L; Coelho, Francisco; Gomes, Newton C M; Silva, Helena; Almeida, Adelaide; Cunha, Angela
The aim of this study was to understand if two species of salt marsh plants, widely distributed in European estuaries (Spartina maritima and Halimione portulacoides) differently influence the distribution, activity, and metabolic physiology of sediment bacterial communities in monospecific banks, in comparison with uncolonized sediment (control). Microbiological descriptors of abundance and activity were assessed along vertical profiles of sediments. Rates of activity of the extracellular enzymes beta-glucosidase, alpha-glucosidase, aminopeptidase, arylsulfatase, and phosphatase were generally higher in the vegetation banks in relation to control sediments where they were also less variable with depth. This is interpreted as an indirect effect related to supply of plant-derived polymeric substrates for bacterial growth. Parameters related to sediment texture (grain size, percent of fines or water content) showed significant relations with cell abundance or maximum hydrolysis rates, pointing to an indirect effect of plant colonization exerted through the modification of sediment physical properties. The profiles of utilization of sole-carbon-source (Biolog Ecoplates) showed that only the communities from the upper sediment layer of the S. maritima and the H. portulacoides banks exhibit consistent differences in terms of physiological profiles. Bacterial communities in control sediments exhibited the lowest physiological variability between surface and sub-surface communities. The results indicate that microbial colonization and organic matter decomposition are enhanced under the influence of salt marsh plants and confirm that plant coverage is a major determinant of the processes of organic matter recycling in intertidal estuarine sediments. PMID:20495797
Salt marsh sediment diversity: a test of the variability of the rare biosphere among environmental replicates
Bowen, Jennifer L; Morrison, Hilary G; Hobbie, John E; Sogin, Mitchell L
Much of the phylogenetic diversity in microbial systems arises from rare taxa that comprise the long tail of taxon rank distribution curves. This vast diversity presents a challenge to testing hypotheses about the effects of perturbations on microbial community composition because variability of rare taxa among environmental replicates may be sufficiently large that it would require a prohibitive degree of sequencing to discern differences between samples. In this study we used pyrosequencing of 16S rRNA tags to examine the diversity and within-site variability of salt marsh sediment bacteria. Our goal was to determine whether pyrosequencing could produce similar patterns in community composition among replicate environmental samples from the same location. We hypothesized that repeated sampling from the same location would produce different snapshots of the rare community due to incomplete sequencing of the taxonomically rich rare biosphere. We demonstrate that the salt marsh sediments we sampled contain a remarkably diverse array of bacterial taxa and, in contrast to our hypothesis, repeated sampling from within the same site produces reliably similar patterns in bacterial community composition, even among rare organisms. These results demonstrate that deep sequencing of 16s tags is well suited to distinguish site-specific similarities and differences among rare taxa and is a valuable tool for hypothesis testing in microbial ecology. PMID:22739491
[Polychaete community in mangrove and salt marsh in Zhangjiang River Estuary, Fujian Province of East China].
Chen, Xin-Wei; Cai, Li-Zhe; Wu, Chen; Peng, Xin; Cao, Jing; Xu, Peng; Liu, Sha; Fu, Su-Jing
In order to understand the community structure of polychaete in different botanic habitats in Zhangjiang River Estuary, an investigation was conducted in the habitats of Kandelia candel, Aegiceras corniculatum, Spartina alterniflora, and Avicennia marina in four seasons, 2010. A total of 15 polychaete species were recorded, and 6 species including Eteone delta, Namalycastis abiuma, Paraleonnates uschakovi, Polydora ciliata, Capitella capitata, and Mediomastus californiensis were found in the four habitats and four seasons. The density, biomass, richness index, evenness index, and diversity index of the polychaete had no significant differences among seasons but significant differences among habitats, and the dominant species of polychaete in S. alterniflora habitat differed from that in the other three mangrove habitats. Pearson correlation analysis showed that in the mangrove and salt marsh, there were no significant correlations between the polychaete parameters (density, biomass, richness index, evenness index, and diversity index) and the environmental factors (sediment temperature, salinity, total organic carbon, and total nitrogen), except that the species number of polychaete had significant correlation with sediment temperature due to the common species of polychaete such as Capitella capitata, Mediomastus californiensis, and Namalycastis abiuma in the mangrove and salt marsh in Zhangjiang River Estuary being of eurytherm and eurysalinity, and resistant to high organic matter content. PMID:22803456
Potential of phytoremediation for the removal of petroleum hydrocarbons in contaminated salt marsh sediments.
Ribeiro, Hugo; Mucha, Ana P; Almeida, C Marisa R; Bordalo, Adriano A
Degradation of petroleum hydrocarbons in colonized and un-colonized sediments by salt marsh plants Juncus maritimus and Phragmites australis collected in a temperate estuary was investigated during a 5-month greenhouse experiment. The efficiency of two bioremediation treatments namely biostimulation (BS) by the addition of nutrients, and bioaugmentation (BA) by addition of indigenous microorganisms was tested in comparison with hydrocarbon natural attenuation in un-colonized and with rhizoremediation in colonized sediments. Hydrocarbon degrading microorganisms and root biomass were assessed as well as hydrocarbon degradation levels. During the study, hydrocarbon degradation in un-colonized sediments was negligible regardless of treatments. Rhizoremediation proved to be an effective strategy for hydrocarbon removal, yielding high rates in most experiments. However, BS treatments showed a negative effect on the J.Āmaritimus potential for hydrocarbon degradation by decreasing the root system development that lead to lower degradation rates. Although both plants and their associated microorganisms presented a potential for rhizoremediation of petroleum hydrocarbons in contaminated salt marsh sediments, results highlighted that nutrient requirements may be distinct among plant species, which should be accounted for when designing cleanup strategies. PMID:24584003
Effects of flooding and warming on soil organic matter mineralization in Avicennia germinans mangrove forests and Juncus roemerianus salt marshes
NASA Astrophysics Data System (ADS)
Lewis, David Bruce; Brown, Jewel A.; Jimenez, Kristine L.
Under a changing climate, coastal wetlands experience sea level rise, warming, and vegetation change, all of which may influence organic matter mineralization. In coastal wetlands of subtropical west-central Florida (USA), we investigated how soil carbon (C) and nitrogen (N) mineralization respond to soil water, temperature, and ecosystem type (Avicennia germinans mangrove forest vs. Juncus roemerianus salt marsh). We evaluated how soil respiration and mineral N concentration varied along a soil moisture gradient, and whether these relationships differed between ecosystem types. Then, we manipulated soils in a 28-d laboratory incubation to evaluate how potentially mineralizable C and N respond to temperature (23 vs. 27Ā░C), soil hydroperiod (inundated 4 vs. 20Āh/d), and soil source. Soil saturation and inundation suppressed short-term (minutes to weeks) C mineralization from near-surface soils. Soil CO2 efflux declined by 65% as soil moisture increased from 75% to 85%, and potentially mineralizable C was 18% lower with a 20-h hydroperiod than with a 4-h hydroperiod. Organic C quality appears to be greater in A.Āgerminans than in J.Āroemerianus soils, as A.Āgerminans soils had higher field CO2 efflux rates and greater mineralizable C:N (despite lower total C:N). Increasing incubation temperature from 23 to 27Ā░C elevated potentially mineralizable C by 40%, indicating that two symptoms of climate change (increased inundation from sea level rise, and warming) may have opposing effects on soil C mineralization. Temperature sensitivity of C mineralization was high for long-hydroperiod soils, however, suggesting that protection of soil organic matter (SOM) due to prolonged inundation will be undermined by warming. Potentially mineralizable N was greater in J.Āroemerianus soils, although in situ mineral N was not different between ecosystems, instead correlating positively with SOM. These results indicate that models forecasting soil elevation responses to climate change might include inundation effects on mineralization rates.
Comparison of Bulk and Compound-Specific Carbon Isotope Analyses and Determination of Carbon Sources to Salt Marsh Sediments Using n-Alkane Distributions (Maine, USA)
NASA Astrophysics Data System (ADS)
Tanner, B. R.; Uhle, M. E.; Kelley, J. T.; Mora, C. I.
Sources of sedimentary organic matter to a Morse River, Maine (USA) salt marsh over the last 3390+/-60 RCYBP are determined using distribution patterns of n-alkanes as well as bulk and compound-specific carbon isotopic analysis. Marsh foraminiferal counts indicate the ubiquitous presence of zone 1B deposits, suggesting that the deposits were laid down ~0.2 to 0.5m above mean high water. Distributions of n-alkanes show a primary contribution from higher plants, confirmed by an average ACL value of 27.5 for the core sediments and CPI values above 3. Many sample depths have a maximum abundance at the C25 alkane. Ten low marsh, high marsh, and higher-high marsh plant species common to Maine salt marshes were sampled, including Spartina alterniflora, Spartina patens, Juncus gerardi and Solidago sempervirens. The ACL value for the average of the 10 marsh species is 29.1. Salicornia europa, usually not considered to be a dominant species in Maine marshes, has a similar n-alkane distribution to many of the salt marsh sediments, suggesting that it is an important source to the biomass of the marsh through time. Bacterial degradation or algal inputs to the marsh sediments appear to be minor. Compound specific carbon isotopic analyses of the C27 alkanes are, on average, 7.2ppt. depleted relative to bulk values, but the two records are strongly correlated (R2 = 0.87), suggesting that marsh plants are "swamping" the bulk carbon isotopic signal. The apparent abundance of a subordinate (though common) salt marsh plant species (Salicornia europa) within our core underscores the importance of using caution when applying mixing models of relatively few plant species to marsh sediments.
Response of a hypersaline salt marsh to a large flood and rainfall event along the west coast of southern Africa
NASA Astrophysics Data System (ADS)
Bornman, T. G.; Adams, J. B.
The Orange Estuary lost 27% (276 ha) of its wetland area near the mouth as a result of bad management practices during the 1980s. The salt marsh has been unable to recover over the last 20 years because of the persistently high soil and groundwater salinity. In 2006, a 1 in 5 year flood occurred that completely covered the desertified salt marsh and floodplain with freshwater. The flood was followed by an above average (>45 mm) winter rainfall. Soil and groundwater sampled in April and August 2004 were compared with 2006 data to quantify the impact of the flood and rainfall event. It was hypothesised that the two freshwater events would significantly reduce the soil and groundwater salinity. However, the results showed no significant difference in sediment electrical conductivity throughout the soil profile over the four sampling periods. Soil moisture and organic content however increased significantly after these events in the surface soil layer. The flood deposited silt and scoured sand from the surface layers in significant quantities. The depth to groundwater in the desertified marsh retained a similar pattern after the flood despite 15 cm changes in depth in places. In 2004 a clear groundwater electrical conductivity gradient was present extending from the less saline north part of the marsh (0-15 mS cm -1) to the central part (120-135 mS cm -1) and decreasing again towards the south (60-75 mS cm -1). The flood served to even out the groundwater salinity across the desertified marsh (60-90 mS cm -1). The flood and high rainfall had a limited impact on the soil and groundwater characteristics. The few significant changes that were recorded were mostly restricted to the surface soil layers and on a small spatial scale. The rainfall did however create numerous pools of low salinity (<60 mS cm -1) water on the marsh surface that provided a brief opportunity for salt marsh seeds to germinate. A further benefit of the flood was the increased tidal reach into the desertified marsh importing freshwater from the river mouth and exporting salt. Despite these responses it is unlikely that the hypersaline salt marsh will revegetate naturally. Human intervention is needed to ensure the rehabilitation of this important Ramsar site.
Visualizing changes in the community structure of sulfur cycling bacteria in nitrogen enriched salt marsh sediments
Vallino, Joseph J.
Visualizing changes in the community structure of sulfur cycling bacteria in nitrogen enriched salt. Nitrogen loading could perturb the sulfur cycle through the introduction of more below ground biomass, and in these ecosystems over 50% of carbon mineralized is due to sulfate reduction. Anthropogenic inputs of nitrogen
Invasion of tamarisk (Tamarix spp.) in a southern California salt marsh
Technology Transfer Automated Retrieval System (TEKTRAN)
Exotic plants have been demonstrated to be one of the greatest threats to wetlands, as they are capable of altering ecosystem-wide physical and biological properties. One of the most problematic invaders in the western United States has been salt cedar, Tamarix sp., and the impacts of this species i...
Free-living plathelminthes in sheep-grazed and ungrazed supralittoral salt marshes of the North Sea: Abundance, biomass, and their significance in food chains
NASA Astrophysics Data System (ADS)
Armonies, W.
The supralittoral salt marshes of the North Sea are marked by high halophyte primary productivity. The environmental factors are strongly fluctuating. Despite these features the metazoan meiofaunal abundance is equal to that found in other littoral habitats. On average 1250 marine metazoans are found per 10 cm 2 in ungrazed and 770 per 10 cm 2 in sheep-grazed supralittoral salt marshes. Nematoda dominate in numerical abundance, Oligochaeta in biomass. Plathelminthes account for 15% of marine metazoans in ungrazed and 5% in grazed salt marshes. Total plathelminth abundance increases with halophyte density, whereas the abundance of diatom-feeding Plathelminthes decreases. In ungrazed marshes on average 104 Plathelminthes are found per 10 cm 2, accounting for a biomass of 0.65 g DWĘm -2. In sheep-grazed marshes the average abundance is only 32 individuals per 10 cm 2, accounting for a biomass of 0.1 g DWĘm -2. Average individual weight is 3.2 ?g DW or 2.5 ?g AFDW. In grazed salt marshes, 30% of plathelminthes feed on diatoms, 66% are predators, and 4% feed on bacteria (gut analysis). In ungrazed salt marshes only 3% are diatom-feeders, and 90% are predators feeding on Nematoda, Copepoda, Oligochaeta, and smaller Plathelminthes. Presumably plathelminthes are top predators on the salt marsh meiofauna.
Relative importance of multiple environmental variables in structuring benthic macroinfaunal assemblages in chronically metal-polluted salt marshes.
Goto, Daisuke; Wallace, William G
In this study, we assessed importance of sediment-associated trace metals in structuring benthic macroinfaunal assemblages along multiple environmental gradients in chronically polluted salt marshes of the Arthur Kill - AK (New York, USA). More than 90% of benthic macroinfaunal communities at the northern AK sites consisted of a considerably large number of only a few polychaete and oligochaete species. Approximately 70% of among-site variances in abundance and biomass of benthic macroinfaunal communities was strongly associated with a few environmental variables; only sediment-associated mercury consistently contributed to a significant proportion of the explained variances in species composition along natural environmental gradients (e.g., salinity). Although sediment-associated copper, lead, and zinc were substantially elevated at some of the AK sites, their ecological impacts on benthic macroinfaunal communities appeared to be negligible. These findings suggest that cumulative metal-specific impacts may have played an important role in structuring benthic macroinfaunal communities in chronically polluted AK ecosystems. PMID:19954802
Aquatic Insects of New York Salt Marsh Associated with Mosquito Larval Habitat and their Potential Utility as Bioindicators
Rochlin, Ilia; Dempsey, Mary E.; Iwanejko, Tom; Ninivaggi, Dominick V.
The aquatic insect fauna of salt marshes is poorly characterized, with the possible exception of biting Diptera. Aquatic insects play a vital role in salt marsh ecology, and have great potential importance as biological indicators for assessing marsh health. In addition, they may be impacted by measures to control mosquitoes such as changes to the marsh habitat, altered hydrology, or the application of pesticides. Given these concerns, the goals of this study were to conduct the first taxonomic survey of salt marsh aquatic insects on Long Island, New York, USA and to evaluate their utility for non-target pesticide impacts and environmental biomonitoring. A total of 18 species from 11 families and five orders were collected repeatedly during the five month study period. Diptera was the most diverse order with nine species from four families, followed by Coleoptera with four species from two families, Heteroptera with three species from three families, then Odonata and the hexapod Collembola with one species each. Water boatmen, Trichocorixa verticalis Fieber (Heteroptera: Corixidae) and a shore fly, Ephydra subopaca Loew (Diptera: Ephydridae), were the two most commonly encountered species. An additional six species; Anurida maritima Guķrin-Mķneville (Collembola: Neanuridae), Mesovelia mulsanti White (Heteroptera: Mesovelidae), Enochrus hamiltoni Horn (Coleoptera: Hydrophilidae), Tropisternus quadristriatus Horn (Coleoptera: Hydrophilidae), Dasyhelea pseudocincta Waugh and Wirth (Diptera: Ceratopogonidae), and Brachydeutera argentata Walker (Diptera: Ephydridae), were found regularly. Together with the less common Erythrodiplax berenice Drury (Odonata: Libellulidae), these nine species were identified as the most suitable candidates for pesticide and environmental impact monitoring due to abundance, position in the food chain, and extended seasonal occurrence. This study represents a first step towards developing an insectbased index of biological integrity for salt marsh health assessment. PMID:22957707
Aquatic insects of New York salt marsh associated with mosquito larval habitat and their potential utility as bioindicators.
Rochlin, Ilia; Dempsey, Mary E; Iwanejko, Tom; Ninivaggi, Dominick V
The aquatic insect fauna of salt marshes is poorly characterized, with the possible exception of biting Diptera. Aquatic insects play a vital role in salt marsh ecology, and have great potential importance as biological indicators for assessing marsh health. In addition, they may be impacted by measures to control mosquitoes such as changes to the marsh habitat, altered hydrology, or the application of pesticides. Given these concerns, the goals of this study were to conduct the first taxonomic survey of salt marsh aquatic insects on Long Island, New York, USA and to evaluate their utility for non-target pesticide impacts and environmental biomonitoring. A total of 18 species from 11 families and five orders were collected repeatedly during the five month study period. Diptera was the most diverse order with nine species from four families, followed by Coleoptera with four species from two families, Heteroptera with three species from three families, then Odonata and the hexapod Collembola with one species each. Water boatmen, Trichocorixa verticalis Fieber (Heteroptera: Corixidae) and a shore fly, Ephydra subopaca Loew (Diptera: Ephydridae), were the two most commonly encountered species. An additional six species; Anurida maritima Guķrin-Mķneville (Collembola: Neanuridae), Mesovelia mulsanti White (Heteroptera: Mesovelidae), Enochrus hamiltoni Horn (Coleoptera: Hydrophilidae), Tropisternus quadristriatus Horn (Coleoptera: Hydrophilidae), Dasyhelea pseudocincta Waugh and Wirth (Diptera: Ceratopogonidae), and Brachydeutera argentata Walker (Diptera: Ephydridae), were found regularly. Together with the less common Erythrodiplax berenice Drury (Odonata: Libellulidae), these nine species were identified as the most suitable candidates for pesticide and environmental impact monitoring due to abundance, position in the food chain, and extended seasonal occurrence. This study represents a first step towards developing an insect-based index of biological integrity for salt marsh health assessment. PMID:22957707
Temporal trends in microbial abundance and biodegradation in Louisiana salt marshes following the Deepwater Horizon oil spill
NASA Astrophysics Data System (ADS)
Mahmoudi, N.; Fulthorpe, R. R.; Zimmerman, A. R.; Silliman, B. R.; Slater, G. F.
The Deepwater Horizon oil spill that began in April 2010 released approximately 4.9 million barrels of crude oil into the Gulf of Mexico waters. Coastal salt marshes experienced moderate to heavy oiling as spilled oils washed ashore and threatened economically important habitats. In situ biodegradation of petroleum by microbes is one of the most effective methods used to remediate oil spills. However, demonstrating biodegradation can be challenging due to heterogeneous distributions of contaminants and dynamic conditions of coastal ecosystems. Salt marshes provide a unique opportunity in which variations in the natural abundance of ?13C can be used to confirm in situ biodegradation of petroleum. Marsh grasses, specifically Spartina sp., have ?13C values of -12 to -14ē whereas the BP crude oil has a ?13C signature of -27ē. Thus, the 13C content of microbial membrane lipids (which reflects their carbon source) can be used to detect incorporation of petroleum-derived carbon. We investigated biodegradation in marsh sediments in oiled and non-oiled portions of Barataria Bay, Louisiana which experienced some of the most extensive oil contamination. Samples were collected 3, 9 and 15 months following Deepwater Horizon oil intrusion to assess biodegradation over time. Total alkane and PAH analyses confirmed that by Oct 2011 (15 months), concentrations had been significantly reduced (by up to 50,000 ug/kg at some sites). Microbial phospholipid fatty acids (PLFA) analysis revealed that cell densities decreased over the 1 year sampling period across both oil-impacted and non-impacted sites indicating that, rather than petroleum presence, seasonal variability was likely the primary control on microbial abundance. The ranges of ?13C PLFA values in oil-impacted (-26.7 to -30.5ē ▒ 1.0) and non-impacted sediments (-24.5 to -33.3ē ▒ 0.7) in Oct 2010 overlap, thereby reducing confidence in confirmation of biodegradation at this time point. However, in Oct 2011, PLFA from oil-impacted and non-impacted sediments were found to have a ?13C difference of 5.4ē (oil-impacted = -31.7ē ▒ 0.5, non-impacted = -26.3ē ▒ 0.5) suggesting that more depleted carbon from petroleum may be cycling within the system one year later notwithstanding the fact that PAH and alkane concentrations at this time are quite low. In order to provide greater resolution and insight into biodegradation, ongoing work is applying natural abundance radiocarbon (14C) analysis of microbial PLFA, which has become a useful tool in elucidating microbial carbon sources in complex environments. Petroleum-derived carbon contains no significant 14C due to its geological age. Therefore, microbial uptake and metabolism of petroleum-derived carbon reduces the 14C content of their membrane lipids relative to the surrounding natural organic matter. Results will allow us to not only confirm biodegradation in situ, but also to assess cycling of petroleum-derived carbon. Concurrently, a survey of the microbial community across all three domains (bacteria, archaea, eukarya) is being carried out by 454 pyrosequencing to confirm the presence of oil-degraders and assess changes in microbial diversity over time. Our study is the first to apply natural abundance radiocarbon analysis to the Deepwater Horizon oil spill and will provide an in depth understanding of biodegradation over time.
Salt Marsh as a Coastal Filter for the Oceans: Changes in Function with Experimental Increases in Nitrogen
Zavaleta, Erika
, University of California Santa Cruz, Santa Cruz, California, United States of America Abstract Coastal salt extreme sea-level-rise simulation, in which all plants died by the summer of the second year. Although agriculture. However, if the marsh is drowned by rising seas, as in our most extreme sea-level rise treatment
Vegetational and Abiotic Analysis of the Salterns of Mangals and Salt Marshes of the West Coast of Florida
Barbara A. Hoffman; Clinton J. Dawes
To determine saltern boundaries, vascular plant distributions were analyzed across nine transects through three tidal communities on the west coast of Florida: a salt marsh in St. Mark's National Wildlife Refuge, a dwarf mangal in upper Tampa Bay and a well developed mangal in Charlotte Harbor. All nine transects had nearly identical soil salinities, ranging from 20 to 40 ppt
Effects of Salt Marsh Altosid(R) Exposure on Female Growth and Reproduction in the Gulf Sand Fiddler Crab, Uca panacea (Abstract). Presented at the 62nd Annual Meeting of the Association of Southern Biologists, 4-7 July 2001, New Orleans, LA. 1 p. Adult Uca panacea were p...
Long-term effects of mercury in a salt marsh: Hysteresis in the distribution of vegetation following recovery from contamination
M. Vßlega; A. I. Lilleb°; M. E. Pereira; A. C. Duarte; M. A. Pardal
During four decades, the Ria de Aveiro was subjected to the loading of mercury from a chlor-alkali industry, resulting in the deposition of several tons of mercury in the sediments. The present study evaluates the impact of this disturbance and the recovery processes, temporally and spatially, by means of examining the richness of the species of salt marsh plants and
Technology Transfer Automated Retrieval System (TEKTRAN)
Claviceps purpurea that is specific to grasses in salt marsh habitats (G3) has previously been identified on Spartina spp. in two locations: New Jersey, USA and Southern England. We have identified G3 in 11 distinct populations including Western Europe, South America, and along the Atlantic and Paci...
Diet choice in an omnivorous salt-marsh crab: different food types, body size, and habitat complexity
Tracy L. Buck; Greg A. Breed; Steven C. Pennings; Margo E. Chase; Martin Zimmer; Thomas H. Carefoot
Studies of diet choice by omnivores have the potential to form conceptual links between studies of diet choice by herbivores, frugivores, detritivores, and predators. We examined diet choice in the omnivorous salt marsh crab Armases cinereum (=Sesarma cinereum (Grapsidae)) in a series of laboratory experiments. Armases is sexually dimorphic, with larger males having relatively larger claws than females. In a
We examined the vascular plant species richness and the extent, density, and height of Spartina species of ten Narragansett Bay, Rhode Island (United States) fringe salt marshes which had a wide range of residential land development N-loadings associated with their watersheds. Si...
Long-term effects of an oil spill on populations of the salt-marsh crab Uca pugnax
C. T. Krebs; K. A. Burns
A spill of fuel oil at West Falmouth, Massachusetts, in 1969, contaminated contiguous salt marshes with up to 6000 micrograms of oil per gram (ppM) of wet mud and affected local populations of Uca pugnax. Directly related to high-sediment oil content were reduced crab density, reduced ratio of females to males, reduced juvenile settlement, heavy overwinter mortality, incorporation of oil
Ecological effects of climate change on salt marsh wildlife: a case study from a highly urbanized estuary
Thorne, Karen M.; Takekawa, John Y.; Elliott-Fisk, Deborah L.
Coastal areas are high-risk zones subject to the impacts of global climate change, with significant increases in the frequencies of extreme weather and storm events, and sea-level rise forecast by 2100. These physical processes are expected to alter estuaries, resulting in loss of intertidal wetlands and their component wildlife species. In particular, impacts to salt marshes and their wildlife will vary both temporally and spatially and may be irreversible and severe. Synergistic effects caused by combining stressors with anthropogenic land-use patterns could create areas of significant biodiversity loss and extinction, especially in urbanized estuaries that are already heavily degraded. In this paper, we discuss current ideas, challenges, and concerns regarding the maintenance of salt marshes and their resident wildlife in light of future climate conditions. We suggest that many salt marsh habitats are already impaired and are located where upslope transgression is restricted, resulting in reduction and loss of these habitats in the future. In addition, we conclude that increased inundation frequency and water depth will have negative impacts on the demography of small or isolated wildlife meta-populations as well as their community interactions. We illustrate our points with a case study on the Pacific Coast of North America at San Pablo Bay National Wildlife Refuge in California, an area that supports endangered wildlife species reliant on salt marshes for all aspects of their life histories.
Fenthion (Baytex), an organophosphate insecticide, is frequently applied to salt-marsh environments to control mosquitoes. hake-flask tests were used to study rates of abiotic and biotic degradation of fenthion and the environmental parameters that affect these rates. Water or wa...
Native plant restoration combats environmental change: development of carbon and nitrogen sequestration capacity using small cordgrass in European salt marshes
Technology Transfer Automated Retrieval System (TEKTRAN)
Restoration of salt marshes is critical in the context of climate change and eutrophication of coastal waters, because their vegetation and sediments may act as carbon and nitrogen sinks. Our primary objectives were to quantify carbon (C) and nitrogen (N) stocks and sequestration rates in restored m...
Examination of Below-Ground Structure and Soil Respiration Rates of Stable and Deteriorating Salt Marshes in Jamaica Bay (NY)
CAT scan imaging is currently being used to examine below-ground peat and root structure in cores collected from salt marshes of Jamaica Bay, part of the Gateway National Recreation Area (NY). CAT scans or Computer-Aided Tomography scans use X-ray equipment to produce multiple i...
Foraminiferal Assemblage Zones of Oregon Salt-Marshes: Implications for Studies of Relative Sea-Level Change
NASA Astrophysics Data System (ADS)
Horton, B.; Hawkes, A. D.; Alan, N.; Kemp, A.
Salt-marsh foraminifera can be useful tools for reconstructing Holocene sea-level change. The use of fossil assemblages as a relative sea-level indicator is underpinned by (1) the relation between characteristic modern foraminiferal assemblages and the tidal frame, (2) that these modern relations can be quantified, and (3) that modern assemblages are representative of past conditions recorded in Holocene salt-marsh sedimentary sequences. Using correspondence and transfer function analysis on large data sets, the former elevation (relative to the tidal frame) of a preserved salt-marsh deposit can be determined from foraminifera therein. This measure of paleomarsh-surface elevation, when combined with other lithostratigraphic data, can be used to infer the past position of local relative sea-level. We have collected sediment samples along elevational transects across the modern surface of seven tidal salt- marshes along coastal Oregon for foraminifera and environmental variables (elevation relative to the tidal frame, loss on ignition, grain size, pH, salinity) to determine the local and regional foraminiferal assemblage zones. Dominant agglutinated taxa in salt-marshes include Balticammina pseudomacresens, Haplophragmoides wilberti, Trochammina inflata, and Miliammina fusca. We will use canonical correspondence analysis of the modern assemblage and environmental data to determine what variable(s) control foraminiferal distribution. Seasonal and temporal changes in assemblage and species infaunality can modify the assemblage zonation decreasing the precision of environmental reconstruction. Therefore we sampled our sites twice throughout the year and compared the collected faunal assemblages and assessed species infaunal migration through staining live foraminifera in 30cm short cores.
Release of Dimethylsulfide from Dimethylsulfoniopropionate by Plant-Associated Salt Marsh Fungi
Bacic, M. K.; Newell, S. Y.; Yoch, D. C.
The range of types of microbes with dimethylsulfoniopropionate (DMSP) lyase capability (enzymatic release of dimethylsulfide [DMS] from DMSP) has recently been expanded from bacteria and eukaryotic algae to include fungi (a species of the genus Fusarium [M. K. Bacic and D. C. Yoch, Appl. Environ. Microbiol. 64:106¢111, 1998]). Fungi (especially ascomycetes) are the predominant decomposers of shoots of smooth cordgrass, the principal grass of Atlantic salt marshes of the United States. Since the high rates of release of DMS from smooth cordgrass marshes have a temporal peak that coincides with peak shoot death, we hypothesized that cordgrass fungi were involved in this DMS release. We tested seven species of the known smooth cordgrass ascomycetes and discovered that six of them exhibited DMSP lyase activity. We also tested two species of ascomycetes from other DMSP-containing plants, and both were DMSP lyase competent. For comparison, we tested 11 species of ascomycetes and mitosporic fungi from halophytes that do not contain DMSP; of these 11, only 3 were positive for DMSP lyase. A third group tested, marine oomycotes (four species of the genera Halophytophthora and Pythium, mostly from mangroves), showed no DMSP lyase activity. Two of the strains of fungi found to be positive for DMSP lyase also exhibited uptake of DMS, an apparently rare combination of capabilities. In conclusion, a strong correlation exists between a fungal decomposerÆs ability to catabolize DMSP via the DMSP lyase pathway and the host plantÆs production of DMSP as a secondary product. PMID:16349548
Ecological Relationships between Meloidogyne spartinae and Salt Marsh Grasses in Connecticut.
Lamondia, J A; Elmer, W H
Healthy specimens of selected grasses were collected from salt marshes and grown in the greenhouse. Plants were inoculated with Meloidogyne spartinae to determine the host range of this nematode. After 12 weeks, Spartina alterniflora plants formed root galls in response to infection and increased M. spartinae populations. Spartina patens, Spartina cynosuroides, Juncus gerardii and Distichlis spicata were non-hosts. In order to determine the natural distribution of M. spartinae in dieback areas, S. alterniflora plants were sampled from transects adjacent to dieback areas in Madison, CT, at low tide. Plants were sampled at the top or the creek and at 1-m intervals to the lowest area of plant growth at the low tide water's edge. Five samples were taken over an elevation drop of 90 cm. Two transects were taken each day on 21 June and 5 July 2007, and one transect was taken on 31 October 2007. Meloidogyne spartinae galls per gram root were higher at the higher elevations. In late June and early July 2007, M. spartinae developed more quickly in the higher elevations, perhaps because peat and sediments were drier and warmer away from low tide water levels. The effects of M. spartinae on S. alterniflora and the role of the nematode in marsh decline and dieback in the northeast United States remain to be determined. PMID:19440262
Nutrient retention in plant biomass and sediments from the salt marsh in Hangzhou Bay estuary, China.
Shao, Xuexin; Wu, Ming; Gu, Binhe; Chen, Yinxu; Liang, Xinqiang
Nutrient load into the ocean can be retained during the process of plant uptake and sedimentation in marshes along the bay zone. Seasonal variations of biomass and nutrient concentration in three dominated plant assemblages and associated sediments were monitored in this study area to determine effects of salt marsh on nutrient retention. Results showed that plant aboveground biomass displayed a unimodal curve with nutrient concentration generally decreased from spring to winter. Belowground biomass was relatively low during the rapid growth period with nutrient concentration tending to decrease and then increase during this period. Plant total nitrogen (TN) pools are higher than total phosphorus (TP) pools, and both pools showed significant seasonal variations. Water purification coefficients (WPC) of nutrients by plant assimilation were 34.4/17.3, 19.3/24.0, and 5.14/6.04Āt/(m(2)Āyear) (TN/TP) for Phragmites australis, Spartina alterniflora, and Scirpus mariqueter, respectively. Overall, these results suggest that higher annual plant biomass and nutrient assimilation contribute to greater nutrient retention capacity and accumulation in sediments, thereby enabling reduced eutrophication in transitional waters. PMID:23589271
Greenhouse Gas and Mercury Emissions from a Salt Marsh on the Bay of Fundy
NASA Astrophysics Data System (ADS)
O'Driscoll, N.; McArthur, G. S.; Risk, D. A.; Dalziel, J.; Beltrami, H.
The Bay of Fundy, primarily situated between the provinces of New Brunswick and Nova Scotia in Canada is known have tides among the highest in the world, where tidal amplitudes have reached 17 m, and regularly exceed 12-13m. The reason for these extremely high tides has been attributed to basin morphology and tidal resonance. Along the margin of the Bay of Fundy, salt marshes are exposed to these high tidal ranges. These salt marshes have unknown greenhouse gas (CO2, CH4 specifically) and mercury trace gas budgets. Tides here exert significant pressure on salt marsh sediments, to the point where gases are visibly seen escaping around the waters edge. This pressure-driven gas transport phenomena is markedly different than most greenhouse gas releases from other sediments, which occurs primarily by diffusion. Our study site in Kingsport, NS, Canada also provides a unique opportunity to examine pressure-driven emissions using differential pressure measurements. This work is significant in determining the role of salt marshes in the carbon and mercury emission budgets in the maritime region, and their sensitivity to environmental forcings. For our study, mercury fluxes were measured using Teflon flux chamber technique with Tekran gaseous mercury analysis, while CO2 and CH4 fluxes were measured at 60 second intervals using a new technique called continuous timeseries-forced diffusion (CT-FD). A portable meteorological station was located on site, with soil temperature, solar radiation, soil O2, and soil-atmosphere differential pressure measurements logged continuously for 10 days and 19 tidal cycles. After the field deployment, the CO2 and CH4 instrumentation was moved to soil plots in mesocosm tidal-simulation benches to conduct experiments that would allow us to separate the difference between tidal forcings and thermally-driven microbial greenhouse gas production in sediments. In the field, differential pressure varied according to tidal cycles and was surprising in that rebound to atmospheric pressure rarely occurred. Instead, pressure gradients were sustained in the sediments during high (excess pressure) and low (pressure deficit) tides. While no compelling relationship appears evident between mercury, CO2, or CH4 flux and tidal height, ratios of flux to solar radiation suggest that tidal inundation and gas release does at least facilitate mercury release from sediments during peak flux times. Low gas diffusivity sediments (very fine, impermeable, compact) are potentially very important at these sites, potentially damping transport rates across the soil surface. Gas bubbles, which can be observed at the incoming waterline, may be preferentially emitted through more permeable sediment layers and subsurface sand channels rather than the surface. The Bay of Fundy setting provides a rather unique and challenging opportunity to study extreme examples of trace gas flux and gas transport dynamics.
Prescribed fire and cutting as tools for reducing woody plant succession in a created salt marsh
Owens, A.B.; Proffitt, C.E.; Grace, J.B.
This paper reports on efforts to reduce woody successional growth by the native shrub Iva frutescens L. in a created salt marsh by using prescribed fire and cutting. Experimental treatments included a winter burn, cutting plants at ground level, and a combination burn-and-cut treatment, with replicate plots of each. Iva frutescens proved to be extremely hardy, with zero mortality following the cutting, burning, or combination treatment; similar levels of regrowth were observed for all treatments. Individual shrub response, however, was found to be related to initial plant size, ground water level and salinity, and two fire characteristics (total heating >60??C and total heat index >60??C). Fire severity, sediment nutrient concentrations, and other abiotic factors had no observable effects. ?? 2007 Springer Science+Business Media B.V.
Aquatic macroinvertebrate communities of natural and ditched potholes in a San Francisco Bay salt marsh
NASA Astrophysics Data System (ADS)
Barnby, Mark A.; Collins, Joshua N.; Resh, Vincent H.
Differences in macroinvertebrate community structure and composition were examined from April 1980 to March 1981 in three potholes that had been ditched for mosquito control and three natural (i.e. unditched) potholes, which are located in a San Francisco Bay, California, U.S.A. salt marsh. Measurements of incipient tidal flooding into potholes (i.e. pothole inundation threshold) indicated that these sites comprise a gradient of tidal influences. Exponential decreases in the frequency and duration of tidal inundation corresponded to linear increases in inundation threshold. Since ditched study sites had low thresholds they tended to be more uniformly and regularly influenced by tides, were less saline, had less variable temperature regimens, and supported less filamentous algae than natural potholes. Habitat conditions were generally more similar among ditched than unditched potholes, but environmental conditions were most severe at natural sites near the upper limit of the inundation threshold gradient, where some potholes desiccate during the dry season each year. Differences in macroinvertebrate communities corresponded to differences in habitat conditions. Species richness and diversity (Simpson's Index) were generally highest near the middle of the inundation threshold gradient, which is a pattern predicted by the Intermediate Disturbance Hypothesis. Analysis of faunal composition using discriminant functions indicated more similarity among potholes located at the lowest positions of the inundation gradient than among potholes with intermediate thresholds. Since ditching lowers the inundation thresholds of potholes, it reduces species richness and diversity, while increasing faunal similarity. As a result, extensive ditching to control salt marsh mosquitoes can reduce the overall complexity of lentic macroinvertebrate communities.
A regional assessment of salt marsh restoration and monitoring in the Gulf of Maine
Konisky, R.A.; Burdick, D.M.; Dionne, M.; Neckles, H.A.
We compiled salt marsh monitoring datasets from 36 complete or imminent restoration projects in the Gulf of Maine to assess regional monitoring and restoration practices. Data were organized by functional indicators and restoration project types (culvert replacement, excavation works, or ditch plugging) then pooled to generate mean values for indicators before restoration, after restoration, and at reference sites. Monitoring data were checked against the regional standards of a voluntary protocol for the Gulf of Maine. Data inventories showed that vegetation and salinity indicators were most frequently collected (89 and 78% of sites, respectively), whereas nekton, bird, and hydrologic measures were collected at only about half of the sites. Reference conditions were monitored at 72% of sites. Indicators were analyzed to see if project sites were degraded relative to reference areas and to detect ecological responses to restoration activities. Results showed that compared to reference areas, prerestoration sites had smaller tidal ranges, reduced salinity levels, greater cover of brackish plants species, and lower cover of halophyte plants. Following restoration, physical factors rebounded rapidly with increased flood and salinity levels after about one year, especially for culvert projects. Biological responses were less definitive and occurred over longer time frames. Plant communities trended toward recovered halophytes and reduced brackish species at 3+ years following restoration. Nekton and avian indicators were indistinguishable among reference, impacted, and restored areas. The protocol was successful in demonstrating restoration response for the region, but results were limited by regional inconsistencies in field practices and relatively few multiyear datasets. To improve future assessment capabilities, we encourage greater adherence to the standard protocol throughout the Gulf of Maine salt marsh restoration community.
The effect of tidal forcing on biogeochemical processes in intertidal salt marsh sediments
Taillefert, Martial; Neuhuber, Stephanie; Bristow, Gwendolyn
Background Early diagenetic processes involved in natural organic matter (NOM) oxidation in marine sediments have been for the most part characterized after collecting sediment cores and extracting porewaters. These techniques have proven useful for deep-sea sediments where biogeochemical processes are limited to aerobic respiration, denitrification, and manganese reduction and span over several centimeters. In coastal marine sediments, however, the concentration of NOM is so high that the spatial resolution needed to characterize these processes cannot be achieved with conventional sampling techniques. In addition, coastal sediments are influenced by tidal forcing that likely affects the processes involved in carbon oxidation. Results In this study, we used in situ voltammetry to determine the role of tidal forcing on early diagenetic processes in intertidal salt marsh sediments. We compare ex situ measurements collected seasonally, in situ profiling measurements, and in situ time series collected at several depths in the sediment during tidal cycles at two distinct stations, a small perennial creek and a mud flat. Our results indicate that the tides coupled to the salt marsh topography drastically influence the distribution of redox geochemical species and may be responsible for local differences noted year-round in the same sediments. Monitoring wells deployed to observe the effects of the tides on the vertical component of porewater transport reveal that creek sediments, because of their confinements, are exposed to much higher hydrostatic pressure gradients than mud flats. Conclusion Our study indicates that iron reduction can be sustained in intertidal creek sediments by a combination of physical forcing and chemical oxidation, while intertidal mud flat sediments are mainly subject to sulfate reduction. These processes likely allow microbial iron reduction to be an important terminal electron accepting process in intertidal coastal sediments. PMID:17567893
Seasonal patterns in energy partitioning of two freshwater marsh ecosystems in the Florida Everglades
NASA Astrophysics Data System (ADS)
Malone, Sparkle L.; Staudhammer, Christina L.; Loescher, Henry W.; Olivas, Paulo; Oberbauer, Steven F.; Ryan, Michael G.; Schedlbauer, Jessica; Starr, Gregory
We analyzed energy partitioning in short- and long-hydroperiod freshwater marsh ecosystems in the Florida Everglades by examining energy balance components (eddy covariance derived latent energy (LE) and sensible heat (H) flux). The study period included several wet and dry seasons and variable water levels, allowing us to gain better mechanistic information about the control of and changes in marsh hydroperiods. The annual length of inundation is ~5 months at the short-hydroperiod site (25░26'16.5?N, 80░35'40.68?W), whereas the long-hydroperiod site (25░33'6.72?N, 80░46'57.36?W) is inundated for ~12 months annually due to differences in elevation and exposure to surface flow. In the Everglades, surface fluxes feed back to wet season precipitation and affect the magnitude of seasonal change in water levels through water loss as LE (evapotranspiration (ET)). At both sites, annual precipitation was higher than ET (1304 versus 1008 at the short-hydroperiod site and 1207 versus 1115 mm yr-1 at the long-hydroperiod site), though there were seasonal differences in the ratio of ET:precipitation. Results also show that energy balance closure was within the range found at other wetland sites (60 to 80%) and was lower when sites were inundated (60 to 70%). Patterns in energy partitioning covaried with hydroperiods and climate, suggesting that shifts in any of these components could disrupt current water and biogeochemical cycles throughout the Everglades region. These results suggest that the complex relationships between hydroperiods, energy exchange, and climate are important for creating conditions sufficient to maintain Everglades ecosystems.
Assessment of phosphogypsum impact on the salt-marshes of the Tinto river (SW Spain): role of natural attenuation processes.
Pķrez-L¾pez, Rafael; Castillo, Julio; Sarmiento, Aguasanta M; Nieto, Josķ M
About 120 Mton of phosphogypsum from the fertiliser industry were stack-piled on the salt-marshes of the Tinto river (Spain). This paper investigates the capacity of salt-marshes to attenuate contamination due to downward leaching from phosphogypsum. Solids and pore-waters were characterized at different depths of the pile to reach the marsh-ground. In superficial zones, metals were highly mobile, and no reduced sulphur was found. However, pollutant concentration decreased in the pore-water in deeper oxygen-restricted zones. Metal removal occurred by precipitation of newly formed sulphides, being this process main responsible for the contamination attenuation. Pyrite-S was the main sulphide component (up to 2528 mg/kg) and occurred as framboids, leading to high degrees of pyritization (up to 97%). The sulphidization reaction is Fe-limited; however, excess of acid-volatile sulphide over other metals cause precipitation of other sulphides, mainly of Cu and As. This decrease in metal mobility significantly minimises the impact of phosphogypsums on the salt-marshes. PMID:21992931
Functional gene pyrosequencing and network analysis: an approach to examine the response of denitrifying bacteria to increased nitrogen supply in salt marsh sediments
Bowen, Jennifer L.; Byrnes, Jarrett E. K.; Weisman, David; Colaneri, Cory
Functional gene pyrosequencing is emerging as a useful tool to examine the diversity and abundance of microbes that facilitate key biogeochemical processes. One such process, denitrification, is of particular importance because it converts fixed nitrate (NO?3) to N2 gas, which returns to the atmosphere. In nitrogen limited salt marshes, removal of NO?3 prior to entering adjacent waters helps prevent eutrophication. Understanding the dynamics of salt marsh microbial denitrification is thus imperative for the maintenance of healthy coastal ecosystems. We used pyrosequencing of the nirS gene to examine the denitrifying community response to fertilization in experimentally enriched marsh plots. A key challenge in the analysis of sequence data derived from pyrosequencing is understanding whether small differences in gene sequences are ecologically meaningful. We applied a novel approach from information theory to determine that the optimal similarity level for clustering DNA sequences into OTUs, while still capturing the ecological complexity of the system, was 88%. With this clustering, phylogenetic analysis yielded 6 dominant clades of denitrifiers, the largest of which, accounting for more than half of all the sequences collected, had no close cultured representatives. Of the 638 OTUs identified, only 11 were present in all plots and no single OTU was dominant. We did, however, find a large number of specialist OTUs that were present only in a single plot. The high degree of endemic OTUs, while accounting for a large proportion of the nirS diversity in the plots, were found in lower abundance than the generalist taxa. The proportion of specialist taxa increased with increasing supply of nutrients, suggesting that addition of fertilizer may create conditions that expand the niche space for denitrifying organisms and may enhance the genetic capacity for denitrification. PMID:24348464
Interpreting Sea Level Rise and Rates of Vertical Marsh Accretion in a Southern New England Tidal Salt Marsh
NASA Astrophysics Data System (ADS)
Orson, R. A.; Warren, R. S.; Niering, W. A.
An investigation of marsh accretion rates on a New England type high marsh (Barn Island Wildlife Management Area, Stonington, Connecticut) reveals that this system is sensitive to changes in sea level and storm activity and the peat can accurately record rates of relative submergence as determined by tide gauge records over intervals of 2-5 decades. The results also suggest that the relationship between the accretion deficit and plant community structure is important when utilizing peat records to reconstruct historic sea-level curves within stable Spartina patenshigh marsh communities. In systems where major vegetation changes are prominent over short periods of time (<50 years), interpretations of sea-level rise should be limited to the system in which they are developed unless careful vertical controls can be maintained on the data and multiple datable horizons can be identified within the substrate. The results of this investigation further show that in a stable Spartina patenscommunity within this particular system there is little vertical translocation of 137Cs, making this isotope a powerful tool for assessing rates of vertical marsh development since 1954.
Sulfur, carbon, and nitrogen isotopes used to trace organic matter flow in the salt-marsh estuaries of Sapelo Island, Georgia
The stable isotopes of sulfur, nitrogen, and carbon were used to trace organic matter flow in salt marshes and cstuarinc waters at Sapelo Island, Georgia. Organic matter inputs from terrestrial sources as detrital input either from forests adjacent to the marshes or from rivers were not dctcctable by their isotopic signatures in estuarine consumers. The results suggest that there are
Seasonal changes in community composition and trophic structure of fish populations of five salt marshes along the Essex coastline, United Kingdom
NASA Astrophysics Data System (ADS)
Green, Benjamin C.; Smith, David J.; Earley, Sarah E.; Hepburn, Leanne J.; Underwood, Graham J. C.
European intertidal salt marshes are important nursery sites for juvenile fish and crustaceans. Due to the increasing threat of habitat loss, the seasonal changes of salt marsh fish communities need to be understood in order to appreciate the ecological and economic importance of the saltmarsh habitat. This study was the first in Great Britain to investigate the seasonal changes of salt marsh fish communities and the variation in community structure between closely located marsh habitats. Between February 2007 and March 2008, five marshes on three estuaries of the Essex coastline were sampled using flume nets to block off intertidal creeks at high tide. Fourteen fish species were caught. The community overall was dominated by three species that made up 91.6% of the total catch: the common goby Pomatoschistus microps (46.2% of the total catch), juvenile herring Clupea harengus (24.3%), and juvenile and larval sea bass Dicentrarchus labrax (21.2%). Cluster analysis demonstrated clear seasonal patterns, with some community structures unique to specific marshes or estuaries. The marsh fish community shifts from a highly diverse community during spring, to a community dominated by D. labrax and P. microps in autumn, and low diversity during winter months. Gravimetric stomach content analysis of fish community identified three main trophic guilds; macroinvertivores, planktivores and omnivores. The macroinvertivore feeding guild contained D. labrax and P. microps, the two most frequently occurring species. This investigation demonstrates the importance of British salt marshes as nursery habitats for commercial fish species.
An experimental method to increase sediment supply to a salt marsh in subsidence dominated environments
Thomas, Robert C.
sacrificial berm constructed around the marsh is a possible approach to address ongoing submergence. The sacrificial berm increases the available sediment supply by allowing partial transmission of waves to create a net transport of sediment into the marsh...
Stochastic description of salt-marsh inundation from mixed astronomical-wind driven tides, with implications for macrophyte growth
NASA Astrophysics Data System (ADS)
Howell, S. M.; Furbish, D. J.; Morris, J. T.
Sea-level rise and sedimentation interact to control productivity on coastal salt marshes since the mean sea level influences flood frequency. Irregularly flooded marshes are inundated during spring and storm tides and during extended periods of north-easterly winds. The weak and irregular inundation in marshes may effect rates of decomposition, organic matter accumulation, and the vertical distribution of marsh vegetation. Whereas astronomical tides are predictable, wind driven tides depend on the strength and direction of the wind. Because these systems are stochastic, a non-hydrodynamic approach is used to describe the tides and determine the distribution of water depths. Here we present a description of salt-marsh inundation from mixed astronomical-wind driven tides that removes the astronomical forcing from water level records to determine the role of wind, storms, and forecasting of stochastic platform wetting. Using a 3 year record of water level and wind from sites in Carteret County, North Carolina, we calculate the mean high water (MHW) level and the ratio of inundation for a given elevation and corresponding macrophyte. The frequency of inundation or marsh platform wetting will vary from the frequency of MHW level, yet it is this stochastic wetting process that determines productivity and plant distribution since infrequent flooding may cause stress or hypersaline conditions. An ARIMA model is used to describe this higher order structure of the inundation signal. Wind can be described as an AR1 and a transfer function model is used to determine the dynamic response of the effect of noise and sustained winds on water levels. Harmonic analysis is also performed for comparison of predicted water levels using various tidal constituents to determine the phases and amplitudes and to explore model simplification.
Salt Marsh development studies at Waquoit Bay, Massachusetts: Influence of geomorphology on long-term plant community structure
NASA Astrophysics Data System (ADS)
Orson, Richard A.; Howes, Brian L.
Stochastic events relating to beach formation and inlet dynamics have been the major factors influencing the development of the Waquoit Bay tidal marshes. This results from the physical structure of the Waquoit Bay system where tidal exchange is limited to one or two small inlets and is in contrast to marsh development in nearby Barnstable Marsh where direct unrestricted exchange with Cape Cod Bay has smoothed the effects of stochastic events on vegetation development. We contend that vegetation development in salt marshes where connections to adjacent waters are restricted will be dominated by abiotic factors (e.g. storms, sedimentation rates, etc.) while those marshes directly linked to open bodies of water and where alterations to hydrodynamic factors are gradual, autecological processes (e.g. interspecific competition) will dominate long-term plant community development. The results from the five marsh systems within the Waquoit Bay complex suggest that once a vegetation change occurs the new community tended to persist for long periods of time (100's-1000's years). Stability of the 'new' community appeared to depend upon the stability of the physical structure of the system and/or time between perturbations necessary to allow the slower autecological processes to have a discernable effect. In order for the plant community to persist as long as observed, the vegetation must also be exerting an influence on the processes of development. Increased production of roots and rhizomes and growth characteristics (density of culms) are some of the factors which help to maintain long-term species dominance. It is clear from this investigation that the structure of the plant community at any one point in time is dependent upon numerous factors including historical developmental influences. To properly assess changes to the present plant community or determine recent rates of accretion, historic developmental trends must be considered. The factors that have influenced the development of marsh in the past will be important in understanding and formulating predictive models in the future.
Nitrogen Cycling and Ecosystem Exchanges in a Virginia Tidal Freshwater Marsh
Neubauer, Scott C.
+ in marsh porewaters. Inputs of N from the estuary and atmosphere were not critical in supporting marsh open N cycle have not yet been identified. Introduction Tidal freshwater marshes lie at the upper end + ]; Grant and Patrick 1970; Simp- son et al. 1978; Bowden et al. 1991; Chambers 1992; Ziegler et al. 1999
Methane, carbon dioxide and nitrous oxide fluxes from a temperate salt marsh: Grazing management does not alter Global Warming Potential
NASA Astrophysics Data System (ADS)
Ford, Hilary; Garbutt, Angus; Jones, Laurence; Jones, Davey L.
Soil greenhouse gas emissions from cattle grazed and un-grazed temperate upper salt marsh were measured using dark static chambers, monthly for one year. Below-ground gas sampling tubes were also used to measure soil methane (CH4) concentrations. CH4 efflux from grazed and un-grazed salt marsh did not differ significantly although grazing did lead to 'hotspots' of underground CH4 (up to 6% of total air volume) and CH4 efflux (peak of 9 mg m-2 h-1) significantly linked to high soil moisture content, low soil temperatures and the presence of Juncus gerardii. Carbon dioxide (CO2) efflux was greater from the un-grazed marsh (mean of 420 mg m-2 h-1) than the grazed marsh (mean of 333 mg m-2 h-1) throughout most of the year and was positively correlated with the deeper water table and greater soil temperatures. Grazing was not a significant predictor of nitrous oxide (N2O) soil emissions. Global Warming Potential (GWP; over 100 years), calculated from mean yearly chamber fluxes for CH4 and CO2, did not differ significantly with grazing treatment. Seasonal variation in the key drivers of soil greenhouse gas efflux; soil temperature, moisture and water table, plus the presence or absence of aerenchymatous plants such as J. gerardii were more important to the magnitude of greenhouse gas emissions than grazing management per se.
Holocene salt marsh plant communities in the North Adriatic coastal plain (Italy) as reflected by pollen, non-pollen palynomorphs and plant macrofossil analyses
Antonella Miola; Sonia Favaretto; Ismaele Sostizzo; Gianna Valentini; Alessandra Asioli
In this work we investigate the development of a salt marsh environment during the Holocene marine transgression in the North\\u000a Adriatic coast (North Italy) near the pre-Roman and Roman towns of Cittanova and Concordia Sagittaria. Pollen, plant macrofossils,\\u000a non-pollen palynomorphs (NPPs) and foraminifers are analysed in cores and archaeological excavations to indicate the development\\u000a of salt marsh plant communities. Other
Vegetation death and rapid loss of surface elevation in two contrasting Mississippi delta salt marshes: The role of sedimentation, autocompaction and sea-level rise
Day, J.W.; Kemp, G.P.; Reed, D.J.; Cahoon, D.R.; Boumans, R.M.; Suhayda, J.M.; Gambrell, R.
From 1990 to 2004, we carried out a study on accretionary dynamics and wetland loss in salt marshes surrounding two small ponds in the Mississippi delta; Old Oyster Bayou (OB), a sediment-rich area near the mouth of the Atchafalaya River and Bayou Chitigue (BC), a sediment-poor area about 70. km to the east. The OB site was stable, while most of the marsh at BC disappeared within a few years. Measurements were made of short-term sedimentation, vertical accretion, change in marsh surface elevation, pond wave activity, and marsh soil characteristics. The OB marsh was about 10. cm higher than BC; the extremes of the elevation range for Spartina alterniflora in Louisiana. Vertical accretion and short-term sedimentation were about twice as high at BC than at OB, but the OB marsh captured nearly all sediments deposited, while the BC marsh captured <30%. The OB and BC sites flooded about 15% and 85% of the time, respectively. Marsh loss at BC was not due to wave erosion. The mineral content of deposited sediments was higher at OB. Exposure and desiccation of the marsh surface at OB increased the efficiency that deposited sediments were incorporated into the marsh soil, and displaced the marsh surface upward by biological processes like root growth, while also reducing shallow compaction. Once vegetation dies, there is a loss of soil volume due to loss of root turgor and oxidation of root organic matter, which leads to elevation collapse. Revegetation cannot occur because of the low elevation and weak soil strength. The changes in elevation at both marsh sites are punctuated, occurring in steps that can either increase or decrease elevation. When a marsh is low as at BC, a step down can result in an irreversible change. At this point, the option is not restoration but creating a new marsh with massive sediment input either from the river or via dredging. ?? 2010 Elsevier B.V.
Organochlorine pesticide and polychlorinated biphenyl residues in selected fauna from a New Jersey salt marsh--1967 vs. 1973
Klaas, E.E.; Belisle, A.A.
More than a half million pounds of DDT were applied to control mosquitoes in salt marsh estuaries of Cape May County, New Jersey, from 1946 to 1966. The use of DDT was discontinued in the County after 1966. In 1967, mean concentrations of DDT and metabolites ranged from 0.63 to 9.05 ppm in aquatic fauna, but by 1973 mean residue levels had decreased 84 to 99 percent among nine species. DDE was still present at reduced levels in nearly all samples in 1973, but other DDT isomers had mostly disappeared. Dieldrin was detected only in clapper rails, and residue levels decreased during the period. Mean concentrations of PCB's increased in the clapper rail, remained the same in the fiddler crab and mud snail, and decreased in the sheepshead minnow, mummichog, striped killifish, and salt marsh snail. Small amounts of mirex, toxaphene, cis-chlordane (and/or trans-nonachlor), oxychlordane, and HCB were detected in a few specimens.
Marshes at Chincoteague Channel
Seagrass marshes in Chincoteague Channel. Saltwater and barrier marshes are important ecosystems that protect inland habitat and communities from ocean storms. They also provide important habitat for migrating water fowl. A duck hunting blind can be seen in the right....
Stable Isotope and Biochemical Composition of White Perch in a Phragmites Dominated Salt Marsh and Adjacent Waters
Michael P. Weinstein; Steven Y. Litvin; Vincent G. Guida
Tissue stable isotopes and biochemical condition were compared in two populations of white perch, Morone americana, residing in a Phragmites australis-dominated tidal salt marsh and adjacent open waters of Haverstraw Bay, in the Hudson River estuary, USA. As reported previously\\u000a for other taxa in this system, stable isotope composition of M. americana was influenced by the dominant vegetation present, in
Interactions between a salt marsh native perennial (Salicornia virginica) and an exotic annual (Polypogon monspeliensis) under varied salinity and hydroperiod
J. C. Callaway; J. B. Zedler
An exotic grass invades salt marshes of southern California in very wet years and where there are sewage spills or urban runoff. A series of growth-chamber, mesocosm, and greenhouse experiments explored whether soil salinity and\\/or waterlogging could explain invasion patterns. In all experiments, salinity significantly affected the growth and distribution of Polypogon monspeliensis (rabbit-foot grass, an exotic annual grass) and
Seasonal analyses of arbuscular mycorrhizae, nitrogen-fixing bacteria and growth performance of the salt marsh grass Spartina patens
Allana K. Welsh; David J. Burke; Erik P. Hamerlynck; Dittmar Hahn
Seasonal variation of arbuscular mycorrhizal fungi (AMF) in roots of the high salt marsh plant Spartina patens, the diversity of nitrogen-fixing bacteria in the rhizosphere and plant growth performance was studied at key stages of the\\u000a growing season coinciding with major plant phenological stages, i.e., vegetative growth, reproduction and senescence. AMF\\u000a colonization was highest during vegetative growth, with values declining
Production and life cycle of the gastropod Hydrobia truncata , with notes on Spurwinkia salsa in Massachusetts salt marsh pools
Michael A. Mandracchia; Ernest Ruber
Two hydrobiid gastropods are important components of the salt marsh pool invertebrate community at the Parker River National\\u000a Wildlife Refuge near Rowley, Massachusetts.Hydrobia truncata was found to be the dominant snail in the two higher salinity pools, withSpurwinkia salsa becoming the more important at lower salinities.H. truncata began to reproduce between May 19 and June 9. Cohorts lasted about 14
High Tolerance to Salinity and Herbivory Stresses May Explain the Expansion of Ipomoea Cairica to Salt Marshes
Liu, Gang; Huang, Qiao-Qiao; Lin, Zhen-Guang; Huang, Fang-Fang; Liao, Hui-Xuan; Peng, Shao-Lin
Background Invasive plants are often confronted with heterogeneous environments and various stress factors during their secondary phase of invasion into more stressful habitats. A high tolerance to stress factors may allow exotics to successfully invade stressful environments. Ipomoea cairica, a vigorous invader in South China, has recently been expanding into salt marshes. Methodology/Principal Findings To examine why this liana species is able to invade a stressful saline environment, we utilized I. cairica and 3 non-invasive species for a greenhouse experiment. The plants were subjected to three levels of salinity (i.e., watered with 0, 4 and 8 g L?1 NaCl solutions) and simulated herbivory (0, 25 and 50% of the leaf area excised) treatments. The relative growth rate (RGR) of I. cairica was significantly higher than the RGR of non-invasive species under both stress treatments. The growth performance of I. cairica was not significantly affected by either stress factor, while that of the non-invasive species was significantly inhibited. The leaf condensed tannin content was generally lower in I. cairica than in the non-invasive I. triloba and Paederia foetida. Ipomoea cairica exhibited a relatively low resistance to herbivory, however, its tolerance to stress factors was significantly higher than either of the non-invasive species. Conclusions/Significance This is the first study examining the expansion of I. cairica to salt marshes in its introduced range. Our results suggest that the high tolerance of I. cairica to key stress factors (e.g., salinity and herbivory) contributes to its invasion into salt marshes. For I. cairica, a trade-off in resource reallocation may allow increased resources to be allocated to tolerance and growth. This may contribute to a secondary invasion into stressful habitats. Finally, we suggest that I. cairica could spread further and successfully occupy salt marshes, and countermeasures based on herbivory could be ineffective for controlling this invasion. PMID:23166596
Polychlorinated Biphenyl and Mercury-Associated Alterations on Benthic Invertebrate Community Structure in a Contaminated Salt Marsh in Southeast Georgia
M. T. Horne; N. J. Finley; M. D. Sprenger
.ĀĀ The community structure of a benthic macroinvertebrate assemblage in a contaminated salt marsh was evaluated as part of\\u000a an ecological characterization of a former chloralkali production facility in Georgia. Sample locations were chosen based\\u000a on a gradient of the primary contaminants of concern, total mercury and polychlorinated biphenyls (PCBs), primarily Aroclor\\u000a 1268. Sediment concentrations of Aroclor 1268 ranged from
Quantitative vertical zonation of salt-marsh foraminifera for reconstructing former sea level; an example from New Jersey, USA.
NASA Astrophysics Data System (ADS)
Kemp, Andrew C.; Horton, Benjamin P.; Vann, David R.; Engelhart, Simon E.; Grand Pre, Candace A.; Vane, Christopher H.; Nikitina, Daria; Anisfeld, Shimon C.
We present a quantitative technique to reconstruct sea level from assemblages of salt-marsh foraminifera using partitioning around medoids (PAM) and linear discriminant functions (LDF). The modern distribution of foraminifera was described from 62 surface samples at three salt marshes in southern New Jersey. PAM objectively estimated the number and composition of assemblages present at each site and showed that foraminifera adhered to the concept of elevation-dependent ecological zones, making them appropriate sea-level indicators. Application of PAM to a combined dataset identified five distinctive biozones occupying defined elevation ranges, which were similar to those identified elsewhere on the U.S. mid-Atlantic coast. Biozone A had high abundances of Jadammina macrescens and Trochammina inflata; biozone B was dominated by Miliammina fusca; biozone C was associated with Arenoparrella mexicana; biozone D was dominated by Tiphotrocha comprimata and biozone E was dominated by Haplophragmoides manilaensis. Foraminiferal assemblages from transitional and high salt-marsh environments occupied the narrowest elevational range and are the most precise sea-level indicators. Recognition of biozones in sequences of salt-marsh sediment using LDFs provides a probabilistic means to reconstruct sea level. We collected a core to investigate the practical application of this approach. LDFs indicated the faunal origin of 38 core samples and in cross-validation tests were accurate in 54 of 56 cases. We compared reconstructions from LDFs and a transfer function. The transfer function provides smaller error terms and can reconstruct smaller RSL changes, but LDFs are well suited to RSL reconstructions focused on larger changes and using varied assemblages. Agreement between these techniques suggests that the approach we describe can be used as an independent means to reconstruct sea level or, importantly, to check the ecological plausibility of results from other techniques.
The utilization of an intertidal salt marsh creek by larval and juvenile fishes: Abundance, diversity and temporal variation
Jonathan M. Shenker; John M. Dean
The utilization of an intertidal salt marsh creek in South Carolina during January 1977 was determined by sampling every third\\u000a ebb tide for 13 days. All fishes leaving the creek during that period were captured in a channel net. This procedure produced\\u000a a time-series of samples which permitted analysis of the fish community occupying the intertidal creek at all times
Estimating the contribution of Spartina anglica biomass to salt-marsh sediments using compound specific stable carbon isotope measurements
Ian D. Bull; Pim F. van Bergen; Roland Bol; Sue Brown; Andrew R. Gledhill; Alan J. Gray; Douglas D. Harkness; Simon E. Woodbury; Richard P. Evershed
Compound specific ?13C analyses were used to determine the relative input of a C4 temperate grass (Spartina anglica) to primary biomass in a salt-marsh sediment. Lipid distributions revealed a C32n-alkanol homologue as a characteristically dominant component of Spartina anglica whilst the cohabiting C3 species, Puccinellia maritima, exhibited a C26 maximum. The C32n-alkanol component was used to create an isotopic mixing
Growth patterns of Carolina wolfberry ( Lycium carolinianum L.) in the salt marshes of Aransas National Wildlife Refuge, Texas, USA
Rachel E. Butzler; Stephen E. Davis
The coastal salt marshes of the Aransas National Wildlife Refuge (ANWR), Texas, USA support a wintering population of the\\u000a endangered Whooping Crane (Grus americana). Although the bulk of their winter diet is comprised of blue crabs, berries from the Carolina wolfberry (Lycium carolinianum) can contribute 21¢52% of crane energy intake early in the wintering period. Monthly, from November 2003 to
NSDL National Science Digital Library
Marine ecosystem introduction to shorelines, temperate oceans, and tropical oceans. Shoreline topics cover sandy and rocky shores, barrier islands, tide pools, estuaries, salt marshes, mud flats, mangrove forests, tides, waves, currents, and shoreline animals. Students can learn about temperate ocean zonation, light, forests, patterns, and animals. The tropical oceans chapter features coral reefs and tropical ocean animals. This site would provide a comprehensive introduction for a marine ecosystems or an ocean science unit.
Salt tolerance underlies the cryptic invasion of North American salt marshes by an introduced haplotype of the common reed Phragmites australis (Poaceae)
Vasquez, E.A.; Glenn, E.P.; Brown, J.J.; Guntenspergen, G.R.; Nelson, S.G.
A distinct, non-native haplotype of the common reed Phragmites australis has become invasive in Atlantic coastal Spartina marshes. We compared the salt tolerance and other growth characteristics of the invasive M haplotype with 2 native haplotypes (F and AC) in greenhouse experiments. The M haplotype retained 50% of its growth potential up to 0.4 M NaCl, whereas the F and AC haplotypes did not grow above 0.1 M NaCl. The M haplotype produced more shoots per gram of rhizome tissue and had higher relative growth rates than the native haplotypes on both freshwater and saline water treatments. The M haplotype also differed from the native haplotypes in shoot water content and the biometrics of shoots and rhizomes. The results offer an explanation for how the M haplotype is able to spread in coastal salt marshes and support the conclusion of DNA analyses that the M haplotype is a distinct ecotype of P. australis.
Where temperate meets tropical: Multi-factorial effects of elevated CO2, nitrogen enrichment, and competition on a mangrove-salt marsh community
McKee, K.L.; Rooth, J.E.
Our understanding of how elevated CO2 and interactions with other factors will affect coastal plant communities is limited. Such information is particularly needed for transitional communities where major vegetation types converge. Tropical mangroves (Avicennia germinans) intergrade with temperate salt marshes (Spartina alterniflora) in the northern Gulf of Mexico, and this transitional community represents an important experimental system to test hypotheses about global change impacts on critical ecosystems. We examined the responses of A. germinans (C3) and S. alterniflora (C4), grown in monoculture and mixture in mesocosms for 18 months, to interactive effects of atmospheric CO2 and pore water nitrogen (N) concentrations typical of these marshes. A. germinans, grown without competition from S. alterniflora, increased final biomass (35%) under elevated CO2 treatment and higher N availability. Growth of A. germinans was severely curtailed, however, when grown in mixture with S. alterniflora, and enrichment with CO2 and N could not reverse this growth suppression. A field experiment using mangrove seedlings produced by CO2- and N-enriched trees confirmed that competition from S. alterniflora suppressed growth under natural conditions and further showed that herbivory greatly reduced survival of all seedlings. Thus, mangroves will not supplant marsh vegetation due to elevated CO2 alone, but instead will require changes in climate, environmental stress, or disturbance to alter the competitive balance between these species. However, where competition and herbivory are low, elevated CO2 may accelerate mangrove transition from the seedling to sapling stage and also increase above- and belowground production of existing mangrove stands, particularly in combination with higher soil N. ?? 2008 The Authors Journal compilation ?? 2008 Blackwell Publishing Ltd.
Tidal salt marsh sediment in California, USA: part 3. Current and historic toxicity potential of contaminants and their bioaccumulation.
Hwang, Hyun-Min; Green, Peter G; Young, Thomas M
To assess potential health risks to benthic organisms from exposure to toxic contaminants, sediment chemistry data from five salt marshes along the coast of California were compared with threshold effects levels (TELs) and probable effects levels (PELs). As an integrated estimate of toxicity potential of multiple contaminants, mean PEL quotients (mPELQs) were used to categorize sampling stations into three groups: high (>0.5), medium (0.1-0.5) and low (<0.1). In all sediments from Stege Marsh located in San Francisco Bay, at least one contaminant exceeded PELs by up to 18-fold and mPELQs were higher than 0.7. Mean PELQs in two core sediments from eastern Stege Marsh ranged from 0.7 to 2.1, indicating that benthic organisms in Stege Marsh may have been adversely affected for several decades. To investigate bioavailability and bioaccumulation of contaminants in sediments, longjaw mudsuckers (Gillichthys mirabilis) were transplanted to six Stege Marsh stations for 60 days. Body burdens of organic contaminants clearly showed that they were readily available for benthic organisms. Measured concentrations of organic contaminants in mudsuckers were similar to estimated levels computed using a theoretical bioaccumulation potential model. Levels of PCBs and arsenic in mudsuckers were higher than screening values set as guidelines for the protection of humans and levels of PCBs and DDTs were higher than criteria for wildlife. The results of this study indicate that the levels of contaminants in Stege Marsh sediments may not fully support the well-being of benthic organisms and also may provoke adverse effects on fish-eating animals and humans through trophic transfer. PMID:18316112
Net ecosystem methane and carbon dioxide exchanges in a Lake Erie coastal marsh and a nearby cropland
NASA Astrophysics Data System (ADS)
Chu, Housen; Chen, Jiquan; Gottgens, Johan F.; Ouyang, Zutao; John, Ranjeet; Czajkowski, Kevin; Becker, Richard
Net ecosystem carbon dioxide (FCO2) and methane (FCH4) exchanges were measured by using the eddy covariance method to quantify the atmospheric carbon budget at a Typha- and Nymphaea-dominated freshwater marsh (March 2011 to March 2013) and a soybean cropland (May 2011 to May 2012) in northwestern Ohio, USA. Two year average annual FCH4 (49.7 g C-CH4 m-2 yr-1) from the marsh was high and compatible with its net annual CO2 uptake (FCO2: -21.0 g C-CO2 m-2 yr-1). In contrast, FCH4 was small (2.3 g C-CH4 m-2 yr-1) and accounted for a minor portion of the atmospheric carbon budget (FCO2: -151.8 g C-CO2 m-2 yr-1) at the cropland. At the seasonal scale, soil temperature associated with methane (CH4) production provided the dominant regulator of FCH4 at the marsh (R2 = 0.86). At the diurnal scale, plant-modulated gas flow was the major pathway for CH4 outgassing in the growing season at the marsh. Diffusion and ebullition became the major pathways in the nongrowing season and were regulated by friction velocity. Our findings highlight the importance of freshwater marshes for their efficiency in turning over and releasing newly fixed carbon as CH4. Despite marshes accounting for only ~4% of area in the agriculture-dominated landscape, their high FCH4 should be carefully addressed in the regional carbon budget.
Mercury in non-breeding sparrows of North Carolina salt marshes.
Winder, Virginia L; Emslie, Steven D
We captured Nelson's, Saltmarsh and Seaside Sparrows (Ammodramus nelsoni, A. caudacutus and A. maritimus) at three salt marsh sites near Wrightsville Beach, North Carolina during five non-breeding seasons (September through April, 2006-2011). We analyzed breast feather samples from all of these seasons and blood and first primary feather (P1) samples from three seasons (2008-2011) for mercury (Hg). Generalized linear models were used to test for the impact of species, season, site and month on blood Hg, species, season and site on P1 Hg and species and season on breast feather Hg. The best-fit model for blood indicated that Hg varied among species, seasons and months. Saltmarsh Sparrows maintain higher blood Hg than Nelson's and Seaside Sparrows during the non-breeding season while they are feeding in mixed flocks. In Nelson's and Seaside Sparrows, blood Hg decreased during mid-winter compared to early fall and late spring. Breast feather and P1 Hg varied among species with Saltmarsh Sparrows exhibiting higher concentrations than the other two species, while Nelson's Sparrows had lower concentrations than the other two species. Breast feather Hg was higher in the final three seasons than in the first two. Our results indicate that Hg exposure on breeding sites may be increasing and that high levels of Hg exposure during the breeding season may affect blood Hg concentrations year-round in Saltmarsh Sparrows. Our data thus provide a baseline for future Hg assessments in these species in NC. PMID:21947667
Microscale sulfur cycling in the phototrophic pink berry consortia of the Sippewissett Salt Marsh
Wilbanks, Elizabeth G; Jaekel, Ulrike; Salman, Verena; Humphrey, Parris T; Eisen, Jonathan A; Facciotti, Marc T; Buckley, Daniel H; Zinder, Stephen H; Druschel, Gregory K; Fike, David A; Orphan, Victoria J
Microbial metabolism is the engine that drives global biogeochemical cycles, yet many key transformations are carried out by microbial consortia over short spatiotemporal scales that elude detection by traditional analytical approaches. We investigate syntrophic sulfur cycling in the æpink berryÆ consortia of the Sippewissett Salt Marsh through an integrative study at the microbial scale. The pink berries are macroscopic, photosynthetic microbial aggregates composed primarily of two closely associated species: sulfide-oxidizing purple sulfur bacteria (PB-PSB1) and sulfate-reducing bacteria (PB-SRB1). Using metagenomic sequencing and 34S-enriched sulfate stable isotope probing coupled with nanoSIMS, we demonstrate interspecies transfer of reduced sulfur metabolites from PB-SRB1 to PB-PSB1. The pink berries catalyse net sulfide oxidation and maintain internal sulfide concentrations of 0¢500??m. Sulfide within the berries, captured on silver wires and analysed using secondary ion mass spectrometer, increased in abundance towards the berry interior, while ?34S-sulfide decreased from 6ē to ?31ē from the exterior to interior of the berry. These values correspond to sulfate¢sulfide isotopic fractionations (15¢53ē) consistent with either sulfate reduction or a mixture of reductive and oxidative metabolisms. Together this combined metagenomic and high-resolution isotopic analysis demonstrates active sulfur cycling at the microscale within well-structured macroscopic consortia consisting of sulfide-oxidizing anoxygenic phototrophs and sulfate-reducing bacteria. PMID:24428801
The Relationship of Salt Marsh Vegetation Lateral Obstruction to Vegetation Morphology
NASA Astrophysics Data System (ADS)
Lemein, T.; Cox, D. T.; Albert, D.
Vegetation in salt marshes attenuates wave energy while influencing sediment accretion and turbulence in the water column. Modeling the interaction of waves and vegetation has been typically approached through an empirical coefficient of drag variable that is calibrated for a given set of biologic conditions dependent upon stem density and diameter. This method oversimplifies the complexity of vegetation morphology while also requiring assumptions to be made about the vegetation itself (uniform stem diameters for all stems) and leads to large uncertainty in the drag coefficient. As an alternative to the uniform vegetation model, we focus on the variation of the lateral obstruction of vegetation. This measure of cover in the vertical plane over a given horizontal distance is useful for presenting and quantifying complex vegetation morphology from live, in situ, vegetation. We compare the lateral obstruction of two common Pacific Northwest estuarine species, threesquare bulrush (Schoenoplectus pungens), and Lyngbye's sedge (Carex lyngbyei), to their in situ morphologic characteristics (density, height, diameter, aboveground biomass) over varying horizontal distances. From this, the amount of lateral obstruction is used to determine an estimate of the morphologic characteristics of the species in other environments and vice versa, therefore providing a means of making more accurate comparisons between and among species. We anticipate that this method will improve the calibration of the coefficient of drag variable in wave attenuation equations by incorporating the vertical variation of plant density.
Oxygen dynamics in crude oil contaminated salt marshes: I. Aerobic respiration model.
Shin, W S; Pardue, J H
A simple model was developed to predict oxygen demand exerted by aerobic biodegradation of spilled crude oil and fertilizer added to stimulate biodegradation in salt marsh sediment. The role of aerobic respiration (AR) was determined using first-order G kinetics. The G kinetic rate constants were calculated from laboratory data sets through linear regression. The effect of oil and fertilizer on AR was quantified by comparing three treatments: (i) control (no oil and fertilizer amended), (ii) fertilized, and (iii) oiled and fertilized sediments. The effects of dissolved oxygen concentration in the overlying water and surface mass transfer coefficient were investigated. Aerobic respiration was strongly dependent on the overlying dissolved oxygen concentration when crude oil and fertilizer were added. Oiled/fertilized cores did not show higher SOD and AR than control cores when overlying DO concentration dropped below 5 mg l(-1). Results indicate that higher aerobic respiration in oiled/fertilized is exerted by aerobic biodegradation of crude oil and that major biodegradation of crude oil occurs only when DO level is high (> 5 mg l(-1)). PMID:11506209
Can salt marsh plants influence levels and distribution of DDTs in estuarine areas?
NASA Astrophysics Data System (ADS)
Carvalho, Pedro N.; Rodrigues, Pedro Nuno R.; Evangelista, Rafael; Basto, M. Clara P.; Vasconcelos, M. Teresa S. D.
Sediments are depositories of toxic substances such as organochlorine pesticides and there is a global need for their removal in contaminated environments. Studies that combine contaminated sediments and phytoremediation are relatively recent and their number has been increasing. This work aimed to investigate whether salt marsh plants (sea club-rush Scirpus maritimus, sea rush Juncus maritimus and sea purslane Halimione portulacoides) can favor DDT and metabolites remediation in estuarine environment. For this purpose the levels of DDT, DDE and DDD were compared in vegetated and non-vegetated sediments from an estuary in the North of Portugal ( in-situ study) and from another in the South of Portugal ( ex-situ study). Results obtained both in the in-situ study, involving S. maritimus and J. maritimus, and in the ex-situ study, involving H. portulacoides, indicated that these plants did not have a significant role in DDTs removal and/or degradation. Therefore, it seems that the tested plants cannot influence levels and distribution of DDTs in estuarine areas.
Primary productivity of angiosperm and macroalgae dominated habitats in a New England Salt Marsh: a Comparative analysis
NASA Astrophysics Data System (ADS)
Roman, C. T.; Able, K. W.; Lazzari, M. A.; Heck, K. L.
Net primary productivity estimates were made for the major macrophyte dominated habitats of the Nauset Marsh system, Cape Cod, Massachusetts. Above-ground primary productivity of short form Spartina alterniflora, the dominant habitat of the system, was 664 g m -2 y -1. Productivity of the other dominant angiosperm ( Zostera marina) was estimated to range from 444-987 g m -2 y -1. The marsh creekbank habitat was dominated by an intertidal zone of fucoid algae ( Ascophyllum nodosum ecad. scorpioides, 1179 g m -2 y -1; Fucus vesiculosus, 426 g m -2 y -1), mixed intertidal filamentous algae (91 g m -2 y -1), and a subtidal zone of assorted macroalgae (68 g m -2 y -1). Intertidal mudflats were dominated by Cladophora gracilis, with net production ranging from 59-637 g m -2 y -1. These angiosperm and macrophyte and macrophyte dominated habitats produce over 3 ū 10 6 kg y -1 of biomass (1Ę2 ū 10 6 kg carbon y -1). Twenty-eight per cent (28%) of this carbon production is derived from the Zostera and macroalgae habitats. Although S. alterniflora is considered the major macrophyte primary producer in Nauset Marsh and other north temperate salt marshes, it is concluded that other habitats also contribute significantly to total system carbon production.
Primary productivity of angiosperm and macroalgae dominated habitats in a New England salt marsh: a comparative analysis
Roman, C.T.; Able, K.W.; Lazzari, M.A.; Heck, K.L.
Net primary productivity estimates were made for the major macrophyte dominated habitats of the Nauset Marsh system, Cape Cod, Massachusetts. Above-ground primary productivity of short form Spartina alterniflora, the dominant habitat of the system, was 664 g m-2 y-1. Productivity of the other dominant angiosperm (Zostera marina) was estimated to range from 444?987 g m-2 y-1. The marsh creekbank habitat was dominated by an intertidal zone of fucoid algae (Ascophyllum nodosum ecad. scorpioides, 1179 g m-2 y-1; Fucus vesiculosus, 426 g m-2 y-1), mixed intertidal filamentous algae (91 g m-2 y-1), and a subtidal zone of assorted macroalgae (68 g m-2 y-1). Intertidal mudflats were dominated by Cladophora gracilis, with net production ranging from 59?637 g m-2 y-1. These angiosperm and macrophyte and macrophyte dominated habitats produce over 3 ? 106 kg y-1 of biomass (1?2 ? 106 kg carbon y-1). Twenty-eight per cent (28%) of this carbon production is derived from the Zostera and macroalgae habitats. Although S. alterniflora is considered the major macrophyte primary producer in Nauset Marsh and other north temperate salt marshes, it is concluded that other habitats also contribute significantly to total system carbon production.
Plant-soil interactions in salt marsh environments: Experimental evidence from electrical resistivity tomography in the Venice Lagoon
NASA Astrophysics Data System (ADS)
Boaga, Jacopo; D'Alpaos, Andrea; Cassiani, Giorgio; Marani, Marco; Putti, Mario
The role of root water uptake in regulating soil water saturation in salt marshes is controversial. Modeling studies suggest that soil aeration is improved by transpiration, with implications for the distribution of vegetation species and of the associated topographic features controlling the hydraulic regime of the marshland and eventually its survival. Marsh vegetation plays a key role in the preservation of such critical environment, which represents unique marker for climatic change and impact studies. However, the direct quantification of space-time aeration patterns has remained elusive, in part, because of the limitations posed by high salinity to conventional observation techniques such as time or frequency domain reflectometry. Here we show that time-lapse microscale electrical resistivity tomography, coupled with tensiometric observations, allows the identification of variably saturated zones and the characterization of space-time soil moisture dynamics in a salt marsh in the Venice Lagoon (Italy). This is the first quantitative observational experiment which confirms that periodically flooded plants are capable of producing a persistently aerated layer below the flooded surface when transpiration proceeds at a sufficiently high rate. The experimental results are compared against previously published model predictions.
Effects of long-term grazing on sediment deposition and salt-marsh accretion rates
NASA Astrophysics Data System (ADS)
Elschot, Kelly; Bouma, Tjeerd J.; Temmerman, Stijn; Bakker, Jan P.
Many studies have attempted to predict whether coastal marshes will be able to keep up with future acceleration of sea-level rise by estimating marsh accretion rates. However, there are few studies focussing on the long-term effects of herbivores on vegetation structure and subsequent effects on marsh accretion. Deposition of fine-grained, mineral sediment during tidal inundations, together with organic matter accumulation from the local vegetation, positively affects accretion rates of marsh surfaces. Tall vegetation can enhance sediment deposition by reducing current flow and wave action. Herbivores shorten vegetation height and this could potentially reduce sediment deposition. This study estimated the effects of herbivores on 1) vegetation height, 2) sediment deposition and 3) resulting marsh accretion after long-term (at least 16 years) herbivore exclusion of both small (i.e. hare and goose) and large grazers (i.e. cattle) for marshes of different ages. Our results firstly showed that both small and large herbivores can have a major impact on vegetation height. Secondly, grazing processes did not affect sediment deposition. Finally, trampling by large grazers affected marsh accretion rates by compacting the soil. In many European marshes, grazing is used as a tool in nature management as well as for agricultural purposes. Thus, we propose that soil compaction by large grazers should be taken in account when estimating the ability of coastal systems to cope with an accelerating sea-level rise.
Water movement and salt leaching in drained and irrigated marsh soils of southwest Spain
F. Cabrera; L. Andrew; R. Vaz; J. Martin-Aranda; G. Vachaud
The Guadalquivir river marshes in southwest Spain, are situated in a former estuary that has now been drained. They cover some 140 000 ha. Soils formed in this zone are alluvial, very clayey, salinesodic, and of vertic character with a shallow, very-saline water table. An area within these marshes, reclaimed in 1979, is the object of this detailed study which
In estuaries where seagrass beds adjoin marshes, the import and decomposition of seagrass litter in the marsh provide a mechanism for retaining nutrients within the wetlands and preventing loss to adjacent oceanic waters. Several aspects of the influence of seagrass litter on an ...
Comparison of Nitrogen Fixation Activity in Tall and Short Spartina alterniflora Salt Marsh Soils 1
Hanson, Roger B.
A comparison of the N2 fixers in the tall Spartina alterniflora and short S. alterniflora marsh soils was investigated. Zero-order kinetics and first-order kinetics of acetylene reduction were used to describe the activity of the N2 fixers in marsh soil slurries. It was found that the Vmax values were approximately 10 times greater for the N2 fixers in the tall Spartina than in the short Spartina marsh when raffinose was used as the energy source. In addition, the (Ks + Sn) values were approximately 4 to 15 times lower for the N2 fixers in the tall Spartina than in short Spartina marsh. First-order kinetics of nitrogen fixation for several substrates indicate that the N2 fixers in the tall Spartina marsh were two to seven times more active than those in the short Spartina marsh. Ammonium chloride (25 ?g/ml) did not inhibit nitrogen fixation in the tall Spartina marsh, but there was a 50% inhibition in nitrogen fixation in the short Spartina marsh. On the other hand, sodium nitrate inhibited nitrogen fixation almost 100% at 25 ?g/ml in both soil environments. Amino nitrogen (25 to 100 ?g/ml) had little or no effect on nitrogen fixation. The results indicate that the N2 fixers in the tall Spartina marsh were physiologically more responsive to nutrient addition than those in the short Spartina marsh. This difference in the two populations may be related to the difference in daily tidal influence in the respective areas and thus provide another explanation for the enhanced S. alterniflora production in the creek bank soil system. PMID:16345213
Influence of diesel contamination on the benthic microbial/meiofaunal food web of a Louisiana salt marsh
Carman, K.R.; Fleeger, J.W.; Pomarico, S. [Louisiana State Univ., Baton Rouge, LA (United States). Dept. of Zoology
The authors studied the influence of diesel-contaminated sediments on the benthic microbial/meiofaunal food web from a Louisiana salt marsh. Diesel-contaminated sediment was added to microcosms (intact cores of marsh mud) in a range of doses, and a suite of microbial and meiofaunal responses were measured over a 28-day period. The authors measured bacterial and microalgal (Chl a) abundance, bacterial and microalgal activity using radiotracers ({sup 14}C-acetate and {sup 14}CO{sub 2}, respectively), meiofaunal grazing on microalgae, meiofaunal community structure, and meiofaunal physiological condition. Preliminary results indicate that diesel-contaminated sediments influence microalgal biomass and activity, as well as the life histories of benthic copepod species.
Sources and preservation of organic matter in Plum Island salt marsh sediments (MA, USA): long-chain n-alkanes and stable carbon isotope compositions
NASA Astrophysics Data System (ADS)
Wang, X.-C.; Chen, R. F.; Berry, A.
Elemental (TOC, TN, C/N) and stable carbon isotopic ( ?13C) compositions and n-alkane ( nC 16-38) concentrations were measured for Spartina alterniflora, a C 4 marsh grass, Typha latifolia, a C 3 marsh grass, and three sediment cores collected from middle and upper estuarine sites from the Plum Island salt marshes. Our results indicated that the organic matter preserved in the sediments was highly affected by the marsh plants that dominated the sampling sites. ?13C values of organic matter preserved in the upper fresh water site sediment were more negative ( -23.0▒0.3ē) as affected by the C 3 plants than the values of organic matter preserved in the sediments of middle ( -18.9▒0.8ē) and mud flat sites ( -19.4▒0.1ē) as influenced mainly by the C 4 marsh plants. The distribution of n-alkanes measured in all sediments showed similar patterns as those determined in the marsh grasses S. alterniflora and T. latifolia, and nC 21 to nC 33 long-chain n-alkanes were the major compounds determined in all sediment samples. The strong odd-to-even carbon numbered n-alkane predominance was found in all three sediments and nC 29 was the most abundant homologue in all samples measured. Both ?13C compositions of organic matter and n-alkane distributions in these sediments indicate that the marsh plants could contribute significant amount of organic matter preserved in Plum Island salt marsh sediments. This suggests that salt marshes play an important role in the cycling of nutrients and organic carbon in the estuary and adjacent coastal waters.
Stratification and loading of fecal indicator bacteria (FIB) in a tidally muted urban salt marsh.
Johnston, Karina K; Dorsey, John H; Saez, Jose A
Stratification and loading of fecal indicator bacteria (FIB) were assessed in the main tidal channel of the Ballona Wetlands, an urban salt marsh receiving muted tidal flows, to (1) determine FIB concentration versus loading within the water column at differing tidal flows, (2) identify associations of FIB with other water quality parameters, and (3) compare wetland FIB concentrations to the adjacent estuary. Sampling was conducted four times during spring-tide events; samples were analyzed for FIB and turbidity (NTU) four times over a tidal cycle at pre-allocated depths, depending on the water level. Additional water quality parameters measured included temperature, salinity, oxygen, and pH. Loadings were calculated by integrating the stratified FIB concentrations with water column cross-sectional volumes corresponding to each depth. Enterococci and Escherichia coli were stratified both by concentration and loading, although these variables portrayed different patterns over a tidal cycle. Greatest concentrations occurred in surface to mid-strata levels, during flood tides when contaminated water flowed in from the estuary, and during ebb flows when sediments were suspended. Loading was greatest during flood flows and diminished during low tide periods. FIB concentrations within the estuary often were significantly greater than those within the wetland tide channel, supporting previous studies that the wetlands act as a sink for FIB. For public health water quality monitoring, these results indicate that more accurate estimates of FIB concentrations would be obtained by sampling a number of points within a water column rather than relying only on single surface samples. PMID:25647802
The range expansion patterns of Spartina alterniflora on salt marshes in the Yangtze Estuary, China
NASA Astrophysics Data System (ADS)
Xiao, Derong; Zhang, Liquan; Zhu, Zhenchang
The range expansion patterns of Spartina alterniflora and the roles which sexual reproduction and asexual propagation play in range expansion were investigated at the Chongming Dongtan nature reserve in the Yangtze Estuary, China. Two range expansion patterns of S. alterniflora at its advancing fronts could be found (1) S. alterniflora-mudflat front (S-M) and (2) S. alterniflora- Scirpus mariqueter-mudflat front (S-S-M). One feature revealed by this study was that a flush of seedling recruitment and establishment in spring was a crucial way for S. alterniflora to colonize new habitats and achieve a fast rate of range expansion. The mean number of seedlings recruited at the S-M front was much higher than that at the S-S-M front. Once established, the survivorship of seedlings was high, both at the S-M and S-S-M fronts. The established seedlings formed new tussocks quickly by vegetative tillering and growth of rhizomes and these finally merged into dense meadows. The mean distance of range expansion of S. alterniflora, after one growing season at the S-M front, was 25.4 ▒ 3.1 m yr -1 and 2.7 ▒ 0.5 m yr -1 at the S-S-M front. Sexual reproduction by seedlings and asexual propagation by tillering and growth of rhizomes were the two main means by which S. alterniflora could maintain a fast rate of range expansion on the salt marshes of the Yangtze Estuary. The colonization behaviors of S. alterniflora on advancing fronts differed as a reaction to various external and internal factors. The impact of abiotic and biotic factors governing the range expansion of S. alterniflora and its implications for the spatial structure of tidal wetlands are discussed.
Relationships between salt marsh loss and dredged canals in three Louisiana Estuaries
Bass, A.S.; Turner, R.E.
Coastal land loss rates were quantified for 27 salt marshes in three estuaries of the Louisiana Mississippi Deltaic plain: Barataria, Terrebonne and St. Bernard. The sites ranged from 23 ha to 908 ha and the total area of all sites was 6,367 ha. Two methods were used to calculate open water and canal density in each of five years: (1) a Geographic Information System for 1956 and 1978, and, (2) a point grid method for 1974, 1988, and 1990. A General Linear Model explained 79% of the variance (R2 = 0.79; P ??? 0.95) among basins for all years and provided an estimate of the impacts of canals in each basin. The land loss rates, virtually all occurring as wetland to open water conversions, were different in each basin. The 'background' land loss rates from 1956 to 1990 (exclusive of the direct or indirect effects of canals; %/yr; ?? + 1 Std. Dev.) for each basin were estimated to be: Barataria: 0.71 ?? 0.12, Terrebonne 0.47 ?? 0.09, and St. Bernard 0.08 ?? 0.14. Canals were equally and directly correlated with landloss in each basin. There was 2.85 ha of open water formed with each ha of canal dredged (inclusive of the canal area) and an additional 1 ha wetland converted to spoil bank vegetation. Additional losses may occur if loss rates continue for periods longer than the mapping intervals. There are documented causal mechanisms involving wetland hydrologic changes that can explain these wetland losses.
Sulfate reduction and other sedimentary biogeochemistry in a northern New England salt marsh
NASA Technical Reports Server (NTRS)
Hines, Mark E.; Knollmeyer, Stephen L.; Tugel, Joyce B.
Sulfate reduction rates, dissolved iron and sulfide concentrations, and titration alkalinity were measured in salt marsh soils along a transect that included areas inhabited by both the tall and short forms of Spartina alterniflora and by Spartina patens. Pore waters were collected with in situ 'sippers' to acquire temporal data from the same location without disturbing plant roots. During 1984, data collected at weekly intervals showed rapid temporal changes in belowground biogeochemical processes that coincided with changes in S. alterniflora physiology. Rates of SO4(-2) reduction increased fivefold (to greater than 2.5 micromol ml(sup -1)d(sup -1)) when plants began elongating aboveground yet decreased fourfold upon plant flowering. This rapid increase in rates of SO4(-2) reduction must have been fueled by dissolved organic matter released from roots only during active growth. Once plants flowered, the supply of oxidants to the soil decreased and sulfide and alkalinity concentrations increased despite decreases in SO4(-2) reduction and increases in SO4(-2):Cl(-) ratios. Sulfide concentrations were highest in soils inhabited by tallest plants. During 1985, S. alterniflora became infested with fly larvae (Chaetopsis apicalis John) and aboveground growth ceased in late June. This cessation was accompanied by decreased rates of SO4(-2) reduction similar to those noted during the previous year when flowering occurred. After the fly infestation, the pore-water chemical profiles of these soils resembled profiles of soils inhabited by the short form of S. alterniflora. The SO4(-2) reduction rates in S. patens soils are the first reported. Rates were similar to those in S. alterniflora except that they did not increase greatly when S. patens was elongating. Tidal and rainfall events produced desiccation-saturation cycles that altered redox conditions in the S. patens soils, resulting in rapid changes in the dissolution and precipitation of iron and in the magnitude and spatial distribution of SO4(-2) reduction.
The inner filter effects and their correction in fluorescence spectra of salt marsh humic matter.
Mendonńa, Ana; Rocha, Ana C; Duarte, Armando C; Santos, Eduarda B H
The inner filter effects in synchronous fluorescence spectra (??=60 nm) of sedimentary humic substances from a salt marsh were studied. Accordingly to their type and the influence of plant colonization, these humic substances have different spectral features and the inner filter effects act in a different manner. The fluorescence spectra of the humic substances from sediments with colonizing plants have a protein like band (?exc=280 nm) which is strongly affected by primary and secondary inner filter effects. These effects were also observed for the bands situated at longer wavelengths, i.e., at ?exc=350 nm and ?ex=454 nm for the fulvic acids (FA) and humic acids (HA), respectively. However, they are more important for the band at 280 nm, causing spectral distortions which can be clearly seen when the spectra of solutions 40 mg L(-1) of different samples (Dissolved Organic Carbon - DOC~20 mg L(-1)) are compared with and without correction of the inner filter effects. The importance of the spectral distortions caused by inner filter effects has been demonstrated in solutions containing a mixture of model compounds which represent the fluorophores detected in the spectra of sedimentary humic samples. The effectiveness of the mathematical correction of the inner filter effects in the spectra of those solutions and of solutions of sedimentary humic substances was studied. It was observed that inner filter effects in the sedimentary humic substances spectra can be mathematically corrected, allowing to obtain a linear relationship between the fluorescence intensity and humic substances concentration and preventing distortions at concentrations as high as 50 mg L(-1) which otherwise would obscure the protein like band. PMID:23845487
Effects of migratory geese on plant communities of an Alaskan salt marsh
Zacheis, A.; Hupp, J.W.; Ruess, R.W.
1. We studied the effects of lesser snow geese (Anser caerulescens caerulescens) and Canada geese (Branta canadensis) on two salt marsh plant communities in Cook Inlet, Alaska, a stopover area used during spring migration. From 1995 to 1997 we compared plant species composition and biomass on plots where geese were excluded from feeding with paired plots where foraging could occur. 2. Foraging intensity was low (650-1930 goose-days km-2) compared to other goose-grazing systems. 3. Canada geese fed mainly on above-ground shoots of Triglochin maritimum, Puccinellia spp. and Carex ramenskii, whereas the majority of the snow goose diet consisted of below-ground tissues of Plantago maritima and Triglochin maritimum. 4. Plant communities responded differently to goose herbivory. In the sedge meadow community, where feeding was primarily on above-ground shoots, there was no effect of grazing on the dominant species Carex ramenskii and Triglochin maritimum. In the herb meadow community, where snow geese fed on Plantago maritima roots and other below-ground tissues, there was a difference in the relative abundance of plant species between treatments. Biomass of Plantago maritima and Potentilla egedii was lower on grazed plots compared with exclosed, whereas biomass of Carex ramenskii was greater on grazed plots. There was no effect of herbivory on total standing crop biomass in either community. The variable effect of herbivory on Carex ramenskii between communities suggests that plant neighbours and competitive interactions are important factors in a species' response to herbivory. In addition, the type of herbivory (above- or below-ground) was important in determining plant community response to herbivory. 5. Litter accumulation was reduced in grazed areas compared with exclosed in both communities. Trampling of the previous year's litter into the soil surface by geese incorporated more litter into soils in grazed areas. 6. This study illustrates that even light herbivore pressure can alter plant communities and affect forage availability.
Magnetovibrio blakemorei gen. nov., sp. nov., a magnetotactic bacterium (Alphaproteobacteria: Rhodospirillaceae) isolated from a salt marsh.
Bazylinski, Dennis A; Williams, Timothy J; LefĶvre, Christopher T; Trubitsyn, Denis; Fang, Jiasong; Beveridge, Terrence J; Moskowitz, Bruce M; Ward, Bruce; Sch³bbe, Sabrina; Dubbels, Bradley L; Simpson, Brian
A magnetotactic bacterium, designated strain MV-1(T), was isolated from sulfide-rich sediments in a salt marsh near Boston, MA, USA. Cells of strain MV-1(T) were Gram-negative, and vibrioid to helicoid in morphology. Cells were motile by means of a single polar flagellum. The cells appeared to display a transitional state between axial and polar magnetotaxis: cells swam in both directions, but generally had longer excursions in one direction than the other. Cells possessed a single chain of magnetosomes containing truncated hexaoctahedral crystals of magnetite, positioned along the long axis of the cell. Strain MV-1(T) was a microaerophile that was also capable of anaerobic growth on some nitrogen oxides. Salinities greater than 10?% seawater were required for growth. Strain MV-1(T) exhibited chemolithoautotrophic growth on thiosulfate and sulfide with oxygen as the terminal electron acceptor (microaerobic growth) and on thiosulfate using nitrous oxide (N2O) as the terminal electron acceptor (anaerobic growth). Chemo-organoautotrophic and methylotrophic growth was supported by formate under microaerobic conditions. Autotrophic growth occurred via the Calvin-Benson-Bassham cycle. Chemo-organoheterotrophic growth was supported by various organic acids and amino acids, under microaerobic and anaerobic conditions. Optimal growth occurred at pH 7.0 and 26-28 ░C. The genome of strain MV-1(T) consisted of a single, circular chromosome, about 3.7 Mb in size, with a G+C content of 52.9-53.5 mol%.Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain MV-1(T) belongs to the family Rhodospirillaceae within the Alphaproteobacteria, but is not closely related to the genus Magnetospirillum. The name Magnetovibrio blakemorei gen. nov., sp. nov. is proposed for strain MV-1(T). The type strain of Magnetovibrio blakemorei is MV-1(T) (?=?ATCC BAA-1436(T) ?=?DSM 18854(T)). PMID:22984137
Growth and Photosynthetic Responses to Salinity of the Salt-marsh Shrub Atriplex portulacoides
Redondo-G¾mez, Susana; Mateos-Naranjo, Enrique; Davy, Anthony J.; Fernßndez-Mu±oz, Francisco; Castellanos, Eloy M.; Luque, Teresa; Figueroa, M. Enrique
Background and Aims Atriplex (Halimione) portulacoides is a halophytic, C3 shrub. It is virtually confined to coastal salt marshes, where it often dominates the vegetation. The aim of this study was to investigate its growth responses to salinity and the extent to which these could be explained by photosynthetic physiology. Methods The responses of young plants to salinity in the range 0¢700 mol m?3 NaCl were investigated in a glasshouse experiment. The performance of plants was examined using classical growth analysis, measurements of gas exchange (infrared gas analysis), determination of chlorophyll fluorescence characteristics (modulated fluorimeter) and photosynthetic pigment concentrations; total ash, sodium, potassium and nitrogen concentrations, and relative water content were also determined. Key Results Plants accumulated Na+ approximately in proportion to external salinity. Salt stimulated growth up to an external concentration of 200 mol m?3 NaCl and some growth was maintained at higher salinities. The main determinant of growth response to salinity was unit leaf rate. This was itself reflected in rates of CO2 assimilation, which were not affected by 200 mol m?3 but were reduced at higher salinities. Reductions in net photosynthetic rate could be accounted for largely by lower stomatal conductance and intercellular CO2 concentration. Apart from possible effects of osmotic shock at the beginning of the experiment, salinity did not have any adverse effect on photosystem II (PSII). Neither the quantum efficiency of PSII (?PSII) nor the chlorophyll fluorescence ratio (Fv/Fm) were reduced by salinity, and lower mid-day values recovered by dawn. Mid-day Fv/Fm was in fact depressed more at low external sodium concentration, by the end of the experiment. Conclusions The growth responses of the hygro-halophyte A. portulacoides to salinity appear largely to depend on changes in its rate of photosynthetic gas exchange. Photosynthesis appears to be limited mainly through stomatal conductance and hence intercellular CO2 concentration, rather than by effects on PSII; moderate salinity might stimulate carboxylation capacity. This is in contrast to more extreme halophytes, for which an ability to maintain leaf area can partially offset declining rates of carbon assimilation at high salinity. PMID:17684026
Updated estimates of carbon accumulation rates in coastal marsh sediments
NASA Astrophysics Data System (ADS)
Ouyang, X.; Lee, S. Y.
Studies on carbon stock in salt marsh sediments have increased since the review by Chmura et al. (2003). However, uncertainties exist in estimating global carbon storage in these vulnerable coastal habitats, thus hindering the assessment of their importance. Combining direct data and indirect estimation, this study compiled studies involving 143 sites across the Southern and Northern hemispheres, and provides an updated estimate of the global average carbon accumulation rate (CAR) at 244.7 g C m-2 yr-1 in salt marsh sediments. Based on region-specific CAR and estimates of salt marsh area in various geographic regions between 40░ S to 69.7░ N, total CAR in global salt marsh sediments is estimated at ~10.2 Tg C yr-1. Latitude, tidal range and elevation appear to be important drivers for CAR of salt marsh sediments, with considerable variation among different biogeographic regions. The data indicate that while the capacity for carbon sequestration by salt marsh sediments ranked the first amongst coastal wetland and forested terrestrial ecosystems, their carbon budget was the smallest due to their limited and declining global areal extent. However, some uncertainties remain for our global estimate owing to limited data availability.
Contribution of gaseous sulphur from salt marshes to the global sulphur cycle
NASA Astrophysics Data System (ADS)
Steudler, P. A.; Peterson, B. J.
A synthesis of the results of an annual set of monthly flux measurements of hydrogen sulfide (H2S), dimethyl sulfide, carbonyl sulfide (COS), carbon disulfide (CS2), and dimethyl disulfide from a Spartina marsh and an adjacent tidal creek is reported. Dimethyl sulfide and H2S were the predominant gases released from the Spartina marsh (49 percent and 35 percent of the total, respectively), while H2S was the major gas (71 percent) emitted from the creek site. It is suggested that the short-lived sulfur gases released from marshes may have an important role in local atmospheric sulfur budgets. Globally, saline marshes may release a total of 1.7 Tg S/yr into the atmosphere, which includes more than double the quantity of two important long-lived sulfur gases, COS and CS2, needed to sustain the stratospheric sulfate layer.
The effect of grazing by Littorina irrorata on edaphic and epiphytic communities of salt marsh diatoms
Wu, Tsui-Hui
Samples of natural (ungrazed) and snail-ingested (stomach and fecal) diatom assemblages from a Spartina alterniflora marsh on the southern shore of West Galveston Bay, Texas, were obtained in January, April and August 1992. Littorina irrorata fed...
Importance of local vs. geographic variation in salt marsh plant quality for arthropod herbivore
Pennings, Steven C.
with the presence of predators and top omnivores to mediate herbivore densities. 2. We employed a four-factor fully to marsh elevation), (iii) mesopredator density and (iv) omnivore density. 3. Our results suggest
Quantification of Salt Marsh Carbon Stocks: Integration of Remote Sensing Data and Techniques with Field Measurements
Kulawardhana, Ranjani W
surface, relative sea level history and resulting vegetation transitions as corroborated by historical aerial images. In general, the amounts of soil carbon stored in recently established Spartina alterniflora intertidal marshes were significantly lower...
Utilization of a saltwater-marsh ecosystem for the management of seafood-processing wastewater
Not Available
The report presents the results of a cooperative study that examined the potential for using a saltwater wetland to manage seafood-processing wastewater. An irregularly flooded black needlerush (Juncus roemerianus) marsh located at Point aux Pins in coastal Alabama was selected for the study. The study determined that the application of seafood-processing wastewater to the marsh affected a number of the marsh's water-quality characteristics in direct relation to the wastewater loading rate. However, monitoring of the marsh flora and fauna showed virtually no impact at any of the experimental loading rates. As a result of the study a number of design and loading criteria are suggested for any future projects involving wastewater discharges to saltwater wetlands.
ECOSYSTEM ECOLOGY The effects of tree establishment on water and salt dynamics
Nacional de San Luis, Universidad
ECOSYSTEM ECOLOGY The effects of tree establishment on water and salt dynamics in naturally salt an imprint on salt accumulation and distribution patterns. We explored how the conversion of native grasslands to oak plantations affected the abundance and distribution of salts on soils and groundwater
Comparison of shallow-water and marsh-surface habitats associated with pipeline canals and natural channels in Louisiana salt marshes
Rozas, L.P.
The primary objective of the study was to assess the effects of pipeline canals on the habitat function of inside-levee marshes. The degree to which inside-levee marshes function as nursery habitat for nekton residing in canals was examined by comparing densities of nekton on marshes adjacent to pipeline canals (inside-levee marshes) and natural tidal creeks. In addition, shallow subtidal habitats in the two environments (canals and natural channels) were compared by sampling nekton along the marsh edge at low tide and measuring predator encounter rates in both habitats.
Factors influencing the growth, recruitment success, and distribution of Farfantepenaeus aztecus (Crustacea:Penaeidae) in high and low salinity salt marshes
Aubele, Michael Charles
of 1996 and 1997 20 4 Regression analyses (r') for Farfanfepenaeus aztecus mean density versus selected abiotic and biotic variables in Galveston Bay salt marshes in 1996-97 26 INTRODUCTION The importance of salt marshes as estuarine nursery grounds...), and dissolved oxygen (mg/I) in West Bay in 1996 and 1997. Temperature Salinity Dissolved Oxygen Date min. max. min. max. min. max. 9 Apr96 22 Apr 96 17 May 96 30 May 96 13 Jun 96 18 Jul 96 29 Aug 96 22 Sep 96 17 Oct 96 20&22 Nov 96 13 Feb 97 27 Feb...
Latitudinal variation in top-down and bottom-up control of a salt marsh food web.
Marczak, L B; Ho, C K; Wieski, K; Vu, H; Denno, R F; Pennings, S C
The shrub Iva frutescens, which occupies the terrestrial border of U.S. Atlantic Coast salt marshes, supports a food web that varies strongly across latitude. We tested whether latitudinal variation in plant quality (higher at high latitudes), consumption by omnivores (a crab, present only at low latitudes), consumption by mesopredators (ladybugs, present at all latitudes), or the life history stage of an herbivorous beetle could explain continental-scale field patterns of herbivore density. In a mesocosm experiment, crabs exerted strong top-down control on herbivorous beetles, ladybugs exerted strong top-down control on aphids, and both predators benefited plants through trophic cascades. Latitude of plant origin had no effect on consumers. Herbivorous beetle density was greater if mesocosms were stocked with beetle adults rather than larvae, and aphid densities were reduced in the "adult beetle" treatment. Treatment combinations representing high and low latitudes produced patterns of herbivore density similar to those in the field. We conclude that latitudinal variation in plant quality is less important than latitudinal variation in top consumers and competition in mediating food web structure. Climate may also play a strong role in structuring high-latitude salt marshes by limiting the number of herbivore generations per growing season and causing high overwintering mortality. PMID:21618906
Recent environmental evolution of regenerated salt marshes in the southern Bay of Biscay: Anthropogenic evidences in their sedimentary record
NASA Astrophysics Data System (ADS)
Cearreta, A.; GarcĒa-Artola, A.; Leorri, E.; Irabien, M. J.; Masque, P.
Short sediment cores (up to 44 cm long) taken from salt marshes regenerated during the last 60 years in the Urdaibai Biosphere Reserve have been interpreted on the basis of microfaunal and geochemical determinations and historical data. Agricultural soils in the middle and upper estuary reaches were abandoned during the 1950s and entrance of estuarine water provoked a rapid natural environmental transformation of these anthropogenic areas. Increasing amounts of sand and benthic foraminifera were deposited at a very high sedimentation rate (average 16 mm yr-1) during the 1950s and 1960s allowing well developed regenerated salt marshes to be rapidly established in these formerly occupied areas. During recent decades much lower sedimentation rates (average 2.5 mm yr-1), abundant agglutinated foraminiferal assemblages and enrichment of heavy metals (Pb, Zn, Cu, Ni and Cr) due to industrialization are characteristic of these already regenerated environments. This rapid regeneration process (less than 10 years) is of great interest for environmental management of modern coastal zones where extensive reclaimed land could be easily restored to tidal wetlands under the current scenario of accelerating sea-level rise.
Changes in salt-marsh carabid assemblages after an invasion by the native grass Elymus athericus (Link) Kerguķlen.
Georges, Anita; Fouillet, Philippe; Pķtillon, Julien
As a result of an invasion by the native grass Elymus athericus (Link) Kerguķlen (Poaceae) in the last 10 years, a major change in vegetation cover has occurred in salt marshes of the Mont Saint-Michel bay, Western France. The impact of such an invasion on carabid assemblages, a dominant group of terrestrial arthropods in these habitats and containing several stenotopic species, is investigated here. In our study site, carabid data are available from 1983 and 1984, allowing a comparison of species distribution ranges in salt marshes before (1983-1984) and after (2002) the Elymus athericus invasion. A total of 16,867 adults belonging to 40 species were caught. By considering the presence-absence of species shared between studies, we show that the invasion by Elymus athericus promoted the progression of non-coastal species (mainly Pterostichus s.l. spp.). This did however not interfere with resident species distributions, finally resulting in higher carabid species richness in the entire area. The species composition and abundances of carabid assemblages were also compared between natural and invaded stations in 2002. The main result is that abundances of some halophilic species decreased in one invaded plot (in case of Pogonus chalceus (Marsham 1802)) whereas the opposite pattern was observed for other species (e.g., Bembidion minimum (Fabricius 1792)). Invaded habitats were characterized by lower percentages of halophilic species and higher total species richness. PMID:21738424
Salt tolerance underlies the cryptic invasion of North American salt marshes by an introduced haplotype of the common reed Phragmites australis (Poaceae)
Vasquez, E.A.; Glenn, E.P.; Brown, J.J.; Guntenspergen, G.R.; Nelson, S.G.
A distinct, non-native haplotype of the common reed Phragmites australis has become invasive in Atlantic coastal Spartina marshes. We compared the salt tolerance and other growth characteristics of the invasive M haplotype with 2 native haplotypes (F and AC) in greenhouse experiments. The M haplotype retained 50% of its growth potential up to 0.4 M NaCl, whereas the F and AC haplotypes did not grow above 0.1 M NaCl. The M haplotype produced more shoots per gram of rhizome tissue and had higher relative growth rates than the native haplotypes on both freshwater and saline water treatments. The M haplotype also differed from the native haplotypes in shoot water content and the biometrics of shoots and rhizomes. The results offer an explanation for how the M haplotype is able to spread in coastal salt marshes and support the conclusion of DNA analyses that the M haplotype is a distinct ecotype of P. australis. ?? Inter-Research 2005.
Raster based coastal marsh classification within the Galveston Bay ecosystem, Texas
Edwards, Aron Shaun
shoreline (E2USP), estuarine low marsh (E2EM1N), irregularly flooded intertidal high marsh (E2EM1P), irregularly flooded scrub shrub composed of high tide bush (Iva frutescens) (E2SSP), uplands, composed primarily of coastal prairie (Ur), and urban areas... (E2EM1P); irregularly flooded scrub shrub composed of Iva frutescens (E2SSP); upland range composed primarily of coastal prairie (Ur); urban areas (Uu); commercial/residential buildings (Uub); residential lawns (Uuy); and roads (Uur) utilizing...
The effects of marsh edge and surface elevation on the distribution of salt marsh infauna and prey availability for nekton predators
Whaley, Shannon Diann
, and predators have been found to concentrate in these areas (Baltz et al. 1993; Kneib and Wagner 1994; Minello et al. 1994; Peterson and Turner 1994). Thus, predation pressure could be higher near the marsh edge compared with the inner marsh. In turn... gradient. Predation pressure may be higher near the marsh edge because nektonic predators have been found to concentrate in these areas (Baltz et al. 1993; Kneib and Wagner 1994; Minello et al. 1994; Peterson and Turner 1994). Sediment deposition...
Evidence for preferential depths of metal retention in roots of salt marsh plants
Miguel Caetano; Carlos Vale; Rute Cesßrio; Nuno Fonseca
Depth variation (2-cm resolution) of Fe, Mn, Zn, Cr, Ni, Cu, As and Cd concentrations were determined in belowground biomass of Spartina maritima and Sarcocornia fruticosa and in sediments between roots from two marshes in Tagus (Rosßrio) and Guadiana (Castro Marim) estuaries in Portugal with different anthropogenic pressures. Levels of metals were also determined in aboveground plant parts. Metal concentrations
Modeling wave impact on salt marsh boundaries Mara Tonelli,1,2
Fagherazzi, Sergio
is to evaluate, through analysis of the results of a numerical model, the effect of wave action on marsh a habitat to a diverse animal population, valuable resources for fishing and recreation, and nutrient and vegetation colonization) and those endangering it, such as surface degradation and margin erosion. The rate
Effects of crab halophytic plant interactions on creek growth in a S.W. Atlantic salt marsh: A Cellular Automata model
NASA Astrophysics Data System (ADS)
Minkoff, DarĒo R.; Escapa, Mauricio; Ferramola, Fķlix E.; MaraschĒn, Silvio D.; Pierini, Jorge O.; Perillo, Gerardo M. E.; Delrieux, Claudio
The BahĒa Blanca Estuary (38░ 50' S, and 62░ 30' W) presents salt marshes where interactions between the local flora ( Sarcocornia perennis) and fauna ( Chasmagnathus granulatus) generate some kind of salt pans that alter the normal water circulation and condition its flow and course towards tidal creeks. The crab-vegetation dynamics in the salt marsh presents variations that cannot be quantified in a reasonable period of time. The interaction between S. perennis plant and C. granulatus crab is based on simple laws, but its result is a complex biological mechanism that causes an erosive process on the salt marsh and favors the formation of tidal creeks. To study it, a Cellular Automata model is proposed, based on the laws deduced from the observation of these phenomena in the field, and then verified with measurable data within macroscale time units. Therefore, the objective of this article is to model how the interaction between C. granulatus and S. perennis modifies the landscape of the salt marsh and influences the path of tidal creeks. The model copies the basic laws that rule the problem based on purely biological factors. The Cellular Automata model proved capable of reproducing the effects of the interaction between plants and crabs in the salt marsh. A study of the water drainage of the basins showed that this interaction does indeed modify the development of tidal creeks. Model dynamics would likewise follow different laws, which would provide a different formula for the probability of patch dilation. The patch shape can be obtained changing the pattern that dilates.
Primary Research Paper Ecosystem response to changes in water level of Lake Ontario marshes: lessons
McMaster University
as well as magnitude of flooding in spring can also affect the health of the Great Lake fish community suspended solids and greater light attenuation, light conditions appeared to have been adequate in marsh colonization and light extinction coefficient. I suggest that wave disturbance and propagule burial associated
Seasonal patterns of aboveground plant mass and the depth distribution of live roots, rhizomes, and dead belowground organic matter were measured for Spartina alterniflora and Spartina cynosuroides in Georgia tidal marshes. Peak live aboveground biomass was 1.6x higher for S. cyn...
Quantifying Microbial Utilization of Petroleum Hydrocarbons in Salt Marsh Sediments by Using the 13C Content of Bacterial rRNA?
Pearson, Ann; Kraunz, Kimberly S.; Sessions, Alex L.; Dekas, Anne E.; Leavitt, William D.; Edwards, Katrina J.
Natural remediation of oil spills is catalyzed by complex microbial consortia. Here we took a whole-community approach to investigate bacterial incorporation of petroleum hydrocarbons from a simulated oil spill. We utilized the natural difference in carbon isotopic abundance between a salt marsh ecosystem supported by the 13C-enriched C4 grass Spartina alterniflora and 13C-depleted petroleum to monitor changes in the 13C content of biomass. Magnetic bead capture methods for selective recovery of bacterial RNA were used to monitor the 13C content of bacterial biomass during a 2-week experiment. The data show that by the end of the experiment, up to 26% of bacterial biomass was derived from consumption of the freshly spilled oil. The results contrast with the inertness of a nearby relict spill, which occurred in 1969 in West Falmouth, MA. Sequences of 16S rRNA genes from our experimental samples also were consistent with previous reports suggesting the importance of Gamma- and Deltaproteobacteria and Firmicutes in the remineralization of hydrocarbons. The magnetic bead capture approach makes it possible to quantify uptake of petroleum hydrocarbons by microbes in situ. Although employed here at the domain level, RNA capture procedures can be highly specific. The same strategy could be used with genus-level specificity, something which is not currently possible using the 13C content of biomarker lipids. PMID:18083852
Diversity in leaf anatomy, and stomatal distribution and conductance, between salt marsh and freshwater species in the C(4) genus Spartina (Poaceae).
Maricle, Brian R; Koteyeva, Nuria K; Voznesenskaya, Elena V; Thomasson, Joseph R; Edwards, Gerald E
Leaf anatomy, stomatal density, and leaf conductance were studied in 10 species of Spartina (Poaceae) from low versus high salt marsh, and freshwater habitats. Internal structure, external morphology, cuticle structure, and stomatal densities were studied with light and electron microscopy. Functional significance of leaf structure was examined by measures of CO(2) uptake and stomatal distributions. All species have Kranz anatomy and C(4)delta(13)C values. Freshwater species have thin leaves with small ridges on adaxial sides and stomata on both adaxial and abaxial sides. By contrast, salt marsh species have thick leaves with very pronounced ridges on the adaxial side and stomata located almost exclusively on adaxial leaf surfaces. Salt marsh species also have a thicker cuticle on the abaxial than on the adaxial side of leaves, and CO(2) uptake during photosynthesis is restricted to the adaxial leaf surface. Salt marsh species are adapted to controlling water loss by having stomata in leaf furrows on the adaxial side, which increases the boundary layer, and by having large leaf ridges that fit together as the leaf rolls during water stress. Differences in structural-functional features of photosynthesis in Spartina species are suggested to be related to adaptations to saline environments. PMID:19522838
1088 IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 42, NO. 5, MAY 2004 Classification of Contamination in Salt Marsh Plants
Rocke, David M.
of Contamination in Salt Marsh Plants Using Hyperspectral Reflectance Machelle D. Wilson, Susan L. Ustin, Member and two species of crop plants (in four experiments) that have been exposed to varying levels of different) of exposed and nonexposed plants based on the spectral reflectance data, and partial least squares
Hydrologic forcing of submarine groundwater discharge: Insight from a seasonal study of radium isotopes in a groundwater-dominated salt marsh estuary
Hydrologic forcing of submarine groundwater discharge: Insight from a seasonal study of radium isotopes in a groundwater-dominated salt marsh estuary Matthew A. Charette1 Department of Marine Chemistry of radium-derived submarine groundwater discharge (SGD) and associated nitrogen fluxes was carried out
-FORAGING GEESE, VEGETATION LOSS AND SOIL DEGRADATION IN AN ARCTIC SALT MARSH -7 Applied Vegetation Science 5: 7-16, 2002
Rockwell, Robert F.
patches of sward has restricted growth of these clonal forage plants and hypersalinity of bare sediments- FORAGING GEESE, VEGETATION LOSS AND SOIL DEGRADATION IN AN ARCTIC SALT MARSH - 7 Applied. We describe the long-term effects of increasing numbers of geese at an arctic breeding ground (La
Effectiveness of the aquatic halophyte Sarcocornia perennis spp. perennis as a biotool for ecological restoration of metal-contaminated salt marshes
Technology Transfer Automated Retrieval System (TEKTRAN)
Ecological restoration and creation of salt marshes is needed to compensate for their degradation and loss, but little is known about halophytes as plant biotools in restoration projects. Restoration plantings of halophytes have been established following eradication of invasive populations of the e...
A comparison of a new centrifuge sugar flotation technique with the agar method for the extraction of immature Culicoides (Diptera: Ceratopogonidae) life stages from salt marsh soils.
Technology Transfer Automated Retrieval System (TEKTRAN)
Two sampling techniques, agar extraction (AE) and centrifuge sugar flotation extraction (CSFE) were compared to determine their relative efficacy to recover immature stages of Culicoides spp from salt marsh substrates. Three types of samples (seeded with known numbers of larvae, homogenized field s...
The feasibility of using probes directed towards ribosomal DNAs (rDNAs) as a quantitative approach to estimating cell numbers was examined and applied to study the structure of a bacterial community in humic acid-rich salt marsh sediments. Hybridizations were performed with membr...
Nutrient enrichment and precipitation changes do not enhance resiliency of salt marshes to sea level rise in the Northeastern U.S.
In the U.S. Northeast, salt marshes are exceptionally vulnerable to the effects of accelerated sea level rise as compensatory mechanisms relying on positive feedbacks between inundation and sediment deposition are insufficient to counter inundation increases in low turbidity tida...
Full-waveform and discrete-return lidar in salt marsh environments: An assessment of biophysical parameters, vertical uncertatinty, and nonparametric dem correction
NASA Astrophysics Data System (ADS)
Rogers, Jeffrey N.
High-resolution and high-accuracy elevation data sets of coastal salt marsh environments are necessary to support restoration and other management initiatives, such as adaptation to sea level rise. Lidar (light detection and ranging) data may serve this need by enabling efficient acquisition of detailed elevation data from an airborne platform. However, previous research has revealed that lidar data tend to have lower vertical accuracy (i.e., greater uncertainty) in salt marshes than in other environments. The increase in vertical uncertainty in lidar data of salt marshes can be attributed primarily to low, dense-growing salt marsh vegetation. Unfortunately, this increased vertical uncertainty often renders lidar-derived digital elevation models (DEM) ineffective for analysis of topographic features controlling tidal inundation frequency and ecology. This study aims to address these challenges by providing a detailed assessment of the factors influencing lidar-derived elevation uncertainty in marshes. The information gained from this assessment is then used to: 1) test the ability to predict marsh vegetation biophysical parameters from lidar-derived metrics, and 2) develop a method for improving salt marsh DEM accuracy. Discrete-return and full-waveform lidar, along with RTK GNSS (Real-time Kinematic Global Navigation Satellite System) reference data, were acquired for four salt marsh systems characterized by four major taxa (Spartina alterniflora, Spartina patens, Distichlis spicata, and Salicornia spp.) on Cape Cod, Massachusetts. These data were used to: 1) develop an innovative combination of full-waveform lidar and field methods to assess the vertical distribution of aboveground biomass as well as its light blocking properties; 2) investigate lidar elevation bias and standard deviation using varying interpolation and filtering methods; 3) evaluate the effects of seasonality (temporal differences between peak growth and senescent conditions) using lidar data flown in summer and spring; 4) create new products, called Relative Uncertainty Surfaces (RUS), from lidar waveform-derived metrics and determine their utility; and 5) develop and test five nonparametric regression model algorithms (MARS -- Multivariate Adaptive Regression, CART -- Classification and Regression Trees, TreeNet, Random Forests, and GPSM -- Generalized Path Seeker) with 13 predictor variables derived from both discrete and full waveform lidar sources in order to develop a method of improving lidar DEM quality. Results of this study indicate strong correlations for Spartina alterniflora (r > 0.9) between vertical biomass (VB), the distribution of vegetation biomass by height, and vertical obscuration (VO), the measure of the vertical distribution of the ratio of vegetation to airspace. It was determined that simple, feature-based lidar waveform metrics, such as waveform width, can provide new information to estimate salt marsh vegetation biophysical parameters such as vegetation height. The results also clearly illustrate the importance of seasonality, species, and lidar interpolation and filtering methods on elevation uncertainty in salt marshes. Relative uncertainty surfaces generated from lidar waveform features were determined useful in qualitative/visual assessment of lidar elevation uncertainty and correlate well with vegetation height and presence of Spartina alterniflora. Finally, DEMs generated using full-waveform predictor models produced corrections (compared to ground based RTK GNSS elevations) with R2 values of up to 0.98 and slopes within 4% of a perfect 1:1 correlation. The findings from this research have strong potential to advance tidal marsh mapping, research and management initiatives.
Natural and Restored Tidal Marshes Natural Marshes
Boyer, Katharyn
on reestablishment of hydrological func- tion to lands formerly diked for solar salt produc- tion or agriculture.net/tracker/ba), ranging from less than an acre to the multiple projects within the , -acre South Bay Salt Pond Restoration.1. (A) Former ancient marsh channels still visible in a diked salt evaporation pond. (B) Rare plants
Seed flotation and germination of salt marsh plants: The effects of stratification, salinity, and/or inundation regime
Elsey-Quirk, T.; Middleton, B.A.; Proffitt, C.E.
We examined the effects of cold stratification and salinity on seed flotation of eight salt marsh species. Four of the eight species were tested for germination success under different stratification, salinity, and flooding conditions. Species were separated into two groups, four species received wet stratification and four dry stratification and fresh seeds of all species were tested for flotation and germination. Fresh seeds of seven out of eight species had flotation times independent of salinity, six of which had average flotation times of at least 50 d. Seeds of Spartina alterniflora and Spartina patens had the shortest flotation times, averaging 24 and 26 d, respectively. Following wet stratification, the flotation time of S. alterniflora seeds in higher salinity water (15 and 36 ppt) was reduced by over 75% and germination declined by more than 90%. Wet stratification reduced the flotation time of Distichlis spicata seeds in fresh water but increased seed germination from 2 to 16% in a fluctuating inundation regime. Fresh seeds of Iva frutescens and S. alternflora were capable of germination and therefore are non-dormant during dispersal. Fresh seeds of I. frutescens had similar germination to dry stratified seeds ranging 25-30%. Salinity reduced seed germination for all species except for S. alterniflora. A fluctuating inundation regime was important for seed germination of the low marsh species and for germination following cold stratification. The conditions that resulted in seeds sinking faster were similar to the conditions that resulted in higher germination for two of four species. ?? 2009 Elsevier B.V.
Measuring nutrient flux in Pacific Coast salt marshes using fluctuating water-level chambers
Nutrient removal from the water column is an important ecosystem function that contributes to the production of clean water, a final valued ecosystem service of wetlands. However, little data is currently available for nutrient exchange in Pacific Northwest tidal ecosystems. We h...
Structural Data for the Columbus Salt Marsh Geothermal Area - GIS Data
Faulds, James E.
Shapefiles and spreadsheets of structural data, including attitudes of faults and strata and slip orientations of faults. - Detailed geologic mapping of ~30 km2 was completed in the vicinity of the Columbus Marsh geothermal field to obtain critical structural data that would elucidate the structural controls of this field. - Documenting E? to ENE?striking left lateral faults and N? to NNE?striking normal faults. - Some faults cut Quaternary basalts. - This field appears to occupy a displacement transfer zone near the eastern end of a system of left?lateral faults. ENE?striking sinistral faults diffuse into a system of N? to NNE?striking normal faults within the displacement transfer zone. - Columbus Marsh therefore corresponds to an area of enhanced extension and contains a nexus of fault intersections, both conducive for geothermal activity.
Seasonal cycling of sulfur and iron in porewaters of a Delaware salt marsh
NASA Technical Reports Server (NTRS)
Luther, George W., III; Church, Thomas M.
An extensive pore water data set has been gathered in the Great Marsh, Delaware over various seasons, salinities, and tides. The data all point to a complimentary redox cycle for sulfur and iron which operates seasonally and tidally. Surface oxidizing conditions prevail in summer, with more reducing conditions at depth during the winter. During the spring tides which flood the marsh, pyrite oxidation occurs releasing excess dissolved iron (II) and sulfate to the porewaters, and precipitating authigenic solid iron phases. The redox conditions in the porewaters of the upper zone during the summer is poised between mildly oxidizing and mildly reducing conditions as shown by pE calculations. This redox environment and intermediate iron-sulfur redox species may be important for the stimulation of plant growth (photosynthesis) and sustenance of a viable microbial community (heterotrophy and chemoautropy).
Dispersion of the salt-marsh periwinkle Littoraria irrorata : Effects of water level, size, and season
Caryn C. Vaughn; Frank M. Fisher
This paper documents horizontal and vertical dispersion patterns of a Texas population of the saltmarsh periwinkle, Littoraria irrorata, over a 15-month period. The study was conducted within a tidal marsh on the Anahuac National Wildlife Refuge in Galveston\\u000a Bay. Two mark-recapture experiments demonstrated that L. irrorata rarely move more than 2 m from their release point over long periods of
Nitrogen Fixation (Acetylene Reduction) in a Salt Marsh Amended with Sewage Sludge and Organic Carbon and Nitrogen Compounds 1
Hanson, Roger B.
Seasonal distribution of nitrogen fixation by Spartina alterniflora epiphytes and in surface and soil samples was investigated in a Georgia salt marsh which was amended with sewage sludge or with glucose and/or ammonium nitrate. There was no significant difference between the rates of fixation in the unamended and sewage sludge plots. Additional perturbation experiments suggested that nitrogen addition indirectly stimulates nitrogen fixation by enhancing Spartina production and root exudation. Glucose additions, on the other hand, suppressed nitrogen fixation on a long-term basis. It is suggested that the microbial population in the soil out-competed the plants for the available nitrogen and in turn suppressed plant production and possibly root exudation. A comparison of nitrogen fixation in clipped and unclipped Spartina plots substantiated the suggestion that root exudation probably supports nitrogen fixation. Fixation in the clipped plots was significantly lower (P < 0.05) than the rates in the unclipped plots. PMID:16345239
Seasonal Dynamics of Trace Elements in Tidal Salt Marsh Soils as Affected by the Flow-Sediment Regulation Regime
Bai, Junhong; Xiao, Rong; Zhao, Qingqing; Lu, Qiongqiong; Wang, Junjing; Reddy, K. Ramesh
Soil profiles were collected in three salt marshes with different plant species (i.e. Phragmites australis, Tamarix chinensis and Suaeda salsa) in the Yellow River Delta (YRD) of China during three seasons (summer and fall of 2007 and the following spring of 2008) after the flow-sediment regulation regime. Total elemental contents of As, Cd, Cu, Pb and Zn were determined using inductively coupled plasma atomic absorption spectrometry to investigate temporal variations in trace elements in soil profiles of the three salt marshes, assess the enrichment levels and ecological risks of these trace elements in three sampling seasons and identify their influencing factors. Trace elements did not change significantly along soil profiles at each site in each sampling season. The highest value for each sampling site was observed in summer and the lowest one in fall. Soils in both P. australis and S. salsa wetlands tended to have higher trace element levels than those in T. chinensis wetland. Compared to other elements, both Cd and As had higher enrichment factors exceeding moderate enrichment levels. However, the toxic unit (TU) values of these trace elements did not exceed probable effect levels. Correlation analysis showed that these trace elements were closely linked to soil properties such as moisture, sulfur, salinity, soil organic matter, soil texture and pH values. Principal component analysis showed that the sampling season affected by the flow-sediment regulation regime was the dominant factor influencing the distribution patterns of these trace elements in soils, and plant community type was another important factor. The findings of this study could contribute to wetland conservation and management in coastal regions affected by the hydrological engineering. PMID:25216278
Salt marsh sediment characteristics as key regulators on the efficiency of hydrocarbons bioremediation by Juncus maritimus rhizospheric bacterial community.
Ribeiro, Hugo; Almeida, C Marisa R; MagalhŃes, Catarina; Bordalo, Adriano A; Mucha, Ana P
Mitigation of petroleum hydrocarbons was investigated during a 5-month greenhouse experiment, to assess the rhizoremediation (RR) potential in sediments with different characteristics colonized by Juncus maritimus, a salt marsh plant commonly found in temperate estuaries. Furthermore, the efficiency of two bioremediation treatments namely biostimulation (BS) by the addition of nutrients, and bioaugmentation (BA) by addition of indigenous microorganisms, was tested in combination with RR. The effect of the distinct treatments on hydrocarbon degradation, root biomass weight, and bacterial community structure was assessed. Our result showed higher potential for hydrocarbon degradation (evaluated by total petroleum hydrocarbon analysis) in coarse rhizosediments with low organic matter (OM), than rhizosediments with high OM, and small size particles. Moreover, the bacterial community structure was shaped according to the rhizosediment characteristics, highlighting the importance of specific microbe-particle associations to define the structure of rhizospheric bacterial communities, rather than external factors, such as hydrocarbon contamination or the applied treatments. The potential for hydrocarbon RR seems to depend on root system development and bacterial diversity, since biodegradation efficiencies were positively related with these two parameters. Treatments with higher root biomass, and concomitantly with higher bacterial diversity yielded higher hydrocarbon degradation. Moreover, BS and BA did not enhance hydrocarbons RR. In fact, it was observed that higher nutrient availability might interfere with root growth and negatively influence hydrocarbon degradation performance. Therefore, our results suggested that to conduct appropriate hydrocarbon bioremediation strategies, the effect of sediment characteristics on root growth/exploration should be taken into consideration, a feature not explored in previous studies. Furthermore, strategies aiming for the recovery of bacterial diversity after oil spills may improve the efficiency of hydrocarbon biodegradation in contaminated salt marsh sediments. PMID:25081009
Prokaryotes in salt marsh sediments of Ria de Aveiro: Effects of halophyte vegetation on abundance and diversity
NASA Astrophysics Data System (ADS)
Oliveira, Vanessa; Santos, Ana L.; Aguiar, Cla·dia; Santos, Luisa; Salvador, ┬ngelo C.; Gomes, Newton C. M.; Silva, Helena; Rocha, SĒlvia M.; Almeida, Adelaide; Cunha, ┬ngela
The aim of this study was to investigate the influence of monospecific colonization of sediment stands by Spartina maritima or Halimione portulacoides on benthic prokaryote assemblages in a salt marsh located in Ria de Aveiro (Portugal). The distribution of Bacteria, Archaea and sulfate-reducing bacteria (SRB) in sediments with monospecific plant stands and in unvegetated sediments was characterized by Fluorescence In Situ Hybridization (FISH). Total prokaryote abundance (0.4 ū 109-1.7 ū 109 cells gdw-1) was highest in sediments from the surface layer. The domain Bacteria comprised approximately 40% of total prokaryote communities with the highest percentages occurring in the surface layer. Archaeal cells corresponded to an average of 25% of total prokaryote population, with higher abundance in the vegetation banks, and displaying homogeneous vertical distribution. The relative abundance of SRB represented approximately 3% of total 4', 6-diamidino-2-phenylindole dihydrochloride (DAPI) stained cells at unvegetated sediment and H. portulacoides stand and 7% at S. maritima stand. Headspace solid-phase microextraction (HS-SPME) combined with Comprehensive Two-Dimensional Gas Chromatography-Time-of-Flight Mass Spectrometry (GC ū GC-ToFMS) was used to analyse the volatile and semi-volatile fraction of root exudates. A total of 171 compounds were identified and Principal Component Analysis showed a clear separation between the chemical composition (volatile and semi-volatile organic compounds) of the exudates of the two plants. The patterns of vertical distribution and differences in the proportion of SRB and Archaea in the prokaryote communities developing in sediments colonized by Spartina maritima or Halimione portulacoides suggest the existence of plant-specific interactions between halophyte vegetation and estuarine sediment bacteria in Ria de Aveiro salt marshes, exerted via sediment lithology and root-derived exudates.
Salinity as a constraint on growth of oligohaline marsh macrophytes. II. Salt pulses and recovery potential
Howard, R.J.; Mendelssohn, I.A.
The ability of common oligohaline marsh macrophytes of the northern Gulf of Mexico coast to recover from pulses of increased salinity was investigated in a greenhouse experiment with Eleocharis palustris, Panicum hemitomon, Sagittaria lancifolia, and Scirpus americanus monocultures. Components of salinity pulses applied were final salinity reached (6 or 12 g/L), salinity influx rate (3 d or 3 wk), and duration of exposure (1, 2, or 3 mo). After each exposure period, we placed plants into freshwater until the end of the 120-d experiment to determine recovery potential. The four species varied in their ability to recover from the salinity pulses. Within a species, recovery varied with final salinity level and duration of exposure, and to a lesser extent with salinity influx rate. Scirpus americanus, growth of which was stimulated by <3 mo of exposure to 6 g/L, was able to recover even under the most extreme conditions of exposure to 12 g/L salinity for 3 mo. Ability to recover decreased with increased salinity and increased duration of exposure for the remaining three species. Recovery of specific aspects of growth was also suppressed in these species by a rapid salinity influx rate compared to a slow influx rate. The complex variations in recovery patterns displayed by the different species may lead to changes in species dominance following the short-term salinity pulses that can occur during storm events, which in turn may affect marsh plant community composition and structure.
Salinity as a constraint on growth of oligohaline marsh macrophytes. II. Salt pulses and recovery potential.
Howard, R J; Mendelssohn, I A
The ability of common oligohaline marsh macrophytes of the northern Gulf of Mexico coast to recover from pulses of increased salinity was investigated in a greenhouse experiment with Eleocharis palustris, Panicum hemitomon, Sagittaria lancifolia, and Scirpus americanus monocultures. Components of salinity pulses applied were final salinity reached (6 or 12 g/L), salinity influx rate (3 d or 3 wk), and duration of exposure (1, 2, or 3 mo). After each exposure period, we placed plants into freshwater until the end of the 120-d experiment to determine recovery potential. The four species varied in their ability to recover from the salinity pulses. Within a species, recovery varied with final salinity level and duration of exposure, and to a lesser extent with salinity influx rate. Scirpus americanus, growth of which was stimulated by <3 mo of exposure to 6 g/L, was able to recover even under the most extreme conditions of exposure to 12 g/L salinity for 3 mo. Ability to recover decreased with increased salinity and increased duration of exposure for the remaining three species. Recovery of specific aspects of growth was also suppressed in these species by a rapid salinity influx rate compared to a slow influx rate. The complex variations in recovery patterns displayed by the different species may lead to changes in species dominance following the short-term salinity pulses that can occur during storm events, which in turn may affect marsh plant community composition and structure. PMID:10371722
Impact of permanent inundation on methane emissions from a Spartina alterniflora coastal salt marsh
NASA Astrophysics Data System (ADS)
Ding, Weixin; Zhang, Yaohong; Cai, Zucong
To understand the effect of water level on CH 4 emissions from an invasive Spartina alterniflora coastal brackish marsh, we measured CH 4 emissions from intermittently and permanently (5 cm water depth) inundated mesocosms with or without N fertilizer added at a rate of 2.7 g N m -2. Dissolved CH 4 concentrations in porewater and vertically-profiled sediment redox potential were measured, as were aboveground biomass and stem density of S. alterniflora. Mean CH 4 fluxes during the growing season in permanently inundated mesocosms without and with N fertilizer were 1.03 and 1.73 mg CH 4 m -2 h -1, respectively, which were significantly higher than in the intermittently inundated mesocosms. This response indicates that prolonged submergence of sediment, up to a water depth of 5 cm, stimulated CH 4 release. Inundation did not greatly affect aboveground biomass and stem density, but did significantly reduce redox potential in sediment, which in turn stimulated CH 4 production and increased the CH 4 concentration of porewater, resulting in higher CH 4 emission in the mesocosm. Our data showed that the stimulatory effect of shallow, permanent inundation on CH 4 emission in S. alterniflora marsh sediment was due primarily to an improved methanogenic environment rather than an increase in plant-derived substrates and/or the number of gas emission pathways through the plant's aerenchymal system.
reference to their impact on the salt marsh. Contrib. Mar. Sci. 23, 2555 (1980). 8. Zeil, J. & Layne, J. Crustacean Experimental Systems in Neurobiology (ed. Wiese, K.) 227247 (Springer,
Eddy, Sean
reference to their impact on the salt marsh. Contrib. Mar. Sci. 23, 25┬Ł55 (1980). 8. Zeil, J. & Layne, J. Crustacean Experimental Systems in Neurobiology (ed. Wiese, K.) 227┬Ł247 (Springer, Heidelberg
Trajectory of early tidal marsh restoration: elevation, sedimentation and colonization of breached salt ponds in the northern San Francisco Bay
Brand, L. Arriana; Smith, Lacy M.; Takekawa, John Y.; Athearn, Nicole D.; Taylor, Karen; Shellenbarger, Gregory G.; Schoellhamer, David H.; Spenst, Renee
Tidal marsh restoration projects that cover large areas are critical for maintaining target species, yet few large sites have been studied and their restoration trajectories remain uncertain. A tidal marsh restoration project in the northern San Francisco Bay consisting of three breached salt ponds (?300 ha each; 1175 ha total) is one of the largest on the west coast of North America. These diked sites were subsided and required extensive sedimentation for vegetation colonization, yet it was unclear whether they would accrete sediment and vegetate within a reasonable timeframe. We conducted bathymetric surveys to map substrate elevations using digital elevation models and surveyed colonizing Pacific cordgrass (Spartina foliosa). The average elevation of Pond 3 was 0.96 ▒ 0.19 m (mean ▒ SD; meters NAVD88) in 2005. In 2008¢2009, average pond elevations were 1.05 ▒ 0.25 m in Pond 3, 0.81 ▒ 0.26 m in Pond 4, and 0.84 ▒ 0.24 m in Pond 5 (means ▒ SD; meters NAVD88). The largest site (Pond 3; 508 ha) accreted 9.5 ▒ 0.2 cm (mean ▒ SD) over 4 years, but accretion varied spatially and ranged from sediment loss in borrow ditches and adjacent to an unplanned, early breach to sediment gains up to 33 cm in more sheltered regions. The mean elevation of colonizing S. foliosa varied by pond (F = 71.20, df = 84, P S. foliosa. Our results suggest that sedimentation to elevations that enable vegetation colonization is feasible in large sites with sufficient sediment loads although may occur more slowly compared with smaller sites.
Response of methane emission to invasion of Spartina alterniflora and exogenous N deposition in the coastal salt marsh
NASA Astrophysics Data System (ADS)
Zhang, Yaohong; Ding, Weixin; Cai, Zucong; Valerie, Phillips; Han, Fengxiang
Spartina alterniflora exhibits great invading potential in the coastal marsh ecosystems. Also, nitrogen (N) deposition shows an apparent increase in the east of China. To evaluate CH 4 emissions in the coastal marsh as affected by the invasion of S. alterniflora and N deposition, we measured CH 4 emission from brackish marsh mesocosms vegetated with S. alterniflora and a native plant, Suaeda salsa, and fertilized with exogenous N at the rates of 0 and 2.7 g N m -2, respectively. Dissolved porewater CH 4 concentration and redox potentials in soils as well as aboveground biomass and stem density of plants were also monitored. The averaged rate of CH 4 emission during the growing season in the S. alterniflora and S. salsa mesocosms without N application was 0.88 and 0.54 mg CH 4 m -2 h -1, respectively, suggesting that S. alterniflora plants significantly increased CH 4 emission mainly because of higher plant biomass rather than stem density compared to S. salsa, which delivered more substrates to the soil for methanogenesis. Exogenous N input dramatically stimulated CH 4 emission by 71.7% in the S. alterniflora mesocosm. This increase was attributable to enhancement in biomass and particularly stem density of S. alterniflora driven by N application, which transported greater photosynthesis products than oxygen into soils for CH 4 production and provided more pathways for CH 4 emission. In contrast, there was no significant effect of N fertilization on CH 4 emission in the S. salsa mesocosm. Although N fertilization significantly stimulated CH 4 production by increasing S. salsa biomass, no significant increase in stem density was observed. This fact, along with the low gas transport capacity of S. salsa, failed to efficiently transport CH 4 from wetlands into the atmosphere. Thus we argue that the stimulatory or inhibitory effect of N fertilization on CH 4 emission from wetlands might depend on the gas transport capacity of plants and their relative contribution to substrates for CH 4 production and oxygen for CH 4 oxidation in soil.