text:
@article {64893,
title = {Accuracy assessment and correction of a LIDAR-derived salt marsh digital elevation model},
journal = {Remote Sensing of Enivornment},
year = {2012},
abstract = {Accurate habitat mapping in salt marshes is critical for both management and conservation goals. Information on marsh elevation is important to coastal managers, particularly for flood inundation mapping, coastal hazard assessments and modeling sea level rise. Elevation is also an important determinant of the frequency and duration of tidal flooding, which in turn affects species patterns in marshes: elevation differences of less than 10 cm can affect plant distributions and productivity. Light Detection and Ranging (LIDAR) can provide synoptic elevation information in many environments, but its accuracy in salt marshes is limited by a combination of sensor resolution, instrument errors, and poor laser penetration in dense vegetation. This means that uncorrected digital elevation models (DEM) are generally not accurate enough to distinguish elevation changes in salt marsh environments at the resolution that can be used to determine tidal flooding or vegetation patterns. In this study, we used a LIDAR-derived DEM for the salt marshes surrounding Sapelo Island, GA obtained with a state-of- the- art Optech Gemini ALTM LIDAR system with a high laser pulse rate frequency of 125 kHz and evaluated its accuracy with elevations collected using real time kinematic (RTK) GPS. We found that LIDAR offsets for different cover classes ranged from 0.03 to 0.25 m in comparison to the RTK ground truth data, with the larger offsets for taller vegetation. We developed species-specific correction factors for ten cover classes and used these correction factors to modify the LIDAR-derived DEMs in four test areas of the study domain. Application of the derived correction factors greatly improved the accuracy of the LIDAR DEM, reducing the overall mean LIDAR error from 0.10},
keywords = {dem, GCE, lidar, remote sensing, salt marsh},
doi = {10.1016/j.rse.2012.01.018},
author = {Hladik, Christine M. and Alber, Merryl.}
@article {64912,
title = {Data fusion of hyperspectral and LIDAR imagery for salt marsh mapping},
journal = {Remote Sensing of Environment},
year = {2012},
abstract = {Accurate mapping of both elevation and habitat distribution in salt marshes is important for management and conservation goals. Although Light Detection and Ranging (LIDAR) is effective at measuring surface elevations, laser penetration is limited in dense salt marsh vegetation. In a previous study, we found that LIDAR-derived DEM error varied with vegetation cover and quantified cover class-specific correction factors to reduce DEM errors. As part of this, we found that the three height classes of the dominant macrophyte in Southeastern salt marshes, Spartina alterniflora, required different correction factors. In order to apply these corrections to a LIDAR-derived DEM, it is necessary to have information on the distribution of cover classes at the study site. Hyperspectral imagery (HSI) has been shown to be suitable for the separation of marsh vegetation species by spectral signatures, but there is persistent confusion between the Spartina height classes and mud, which results in what we term the},
keywords = {dem correction, GCE, hyperspectral, lidar, remote sensing, salt marsh},
author = {Hladik, Christine M. and Alber, Merryl. and Schalles, John F.}
@article {80609,
title = {Degradation and resilience in Louisiana salt marshes following the BP-DHW oil spill},
volume = {109},
year = {2012},
pages = {11234-11239},
abstract = {More than 2 y have passed since the BP},
keywords = {GCE, geomorphology, human impacts, multiple stressor, wetland},
author = {Silliman, Brian R. and Diller, J. and McCoy, M. and Earl, Kamala and von de Koppel, J. and Zimmerman, A.}
@article {64913,
title = {Determining the Habitats of Mollusk Collection at the Sapelo Island Shell Ring Complex, USA using Oxygen Isotope Sclerochronology},
journal = {Journal of Archaeological Science},
volume = {39},
year = {2012},
pages = {215-228},
keywords = {archaeology, GCE, georgia},
doi = {10.1016/j.jas.2011.08.002},
author = {Andrus, C. F.T. and Thompson, Victor D.}
@article {64917,
title = {Disturbance and recovery of salt marsh arthropod communities following BP Deepwater Horizon oil spill},
journal = {PLoS ONE},
year = {2012},
abstract = {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. Samplingoccurred 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, Littorariasnails 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 areboth quite vulnerable to oil exposure and quite resilient, able to recover from exposure within a year if host plants remain healthy.},
keywords = {arthropods, bp deepwater horizon, GCE, insects, oil spill, spartina, spiders},
doi = {10.1371/journal.pone.0032735},
url = {http://gce-lter.marsci.uga.edu/public/uploads/McCall_and_Pennings_2012_BP_oil_spill_PLOS_20120307T184551.pdf},
author = {McCall, Brittany DeLoach. and Pennings, Steven C.}
@article {64925,
title = {Effects of an omnivorous katydid, salinity, and nutrients on a planthopper-Spartina food web},
journal = {Estuaries and Coasts},
volume = {35},
year = {2012},
pages = {475-485},
abstract = {Top},
keywords = {GCE, omnivory, orchelimum, prokelisia, spartina, top-down bottom-up},
doi = {10.1007/s12237-011-9458-7},
author = {Jimenez, J. M. and Wieski, Kazimierz. and Marczak, Laurie. and Ho, Chuan-Kai. and Pennings, Steven C.}
@article {80642,
title = {Estimating global "blue carbon" emissions from conversion and degradation of coastal ecosystems},
volume = {7},
year = {2012},
pages = {1-7},
abstract = {Recent attention has focused on the high rates of annual carbon sequestration in vegetated coastal ecosystems},
keywords = {blue carbon emissions, coastal ecosystems, conversion and degradation, GCE},
author = {Pendleton, L. and Marba, N. and Megonigal, P. and Pidgeon, E. and Bilbao-Bastida, V. and Ullman, R. and Herr, D. and Gordon, D and Baldera, A. and Donato, D. and Murray, B. and Crooks, S. and Jenkins, W. and Sifleet, S. and Craft, C. and Fourequrean, J. and Kaufman, J.}
@article {80657,
title = {Habitat Use by Coastal Birds Inferred from Stable Carbon and Nitrogen Isotopes},
volume = {35},
year = {2012},
pages = {633-645},
abstract = {Conservationists need to know the degree of habitat fidelity for species of conservation concern. Stable Isotope Analysis in R quantified the contribution of terrestrial vs. saltmarsh primary production sources to terrestrial passerine food webs from four habitats of Sapelo Island, Georgia (USA), saltmarsh, maritime scrub},
keywords = {coastal birds, food webs, GCE},
author = {Brittain, R.A. and Schimmelmann, A. and Parkhurst, D. and Craft, C.}
@article {80669,
title = {Incorporating clonal growth form clarifies the role of plant height in response to nitrogen addition},
volume = {169},
year = {2012},
pages = {1053-1062},
abstract = {Nutrient addition to grasslands consistentlycauses species richness declines and productivity increases.Competition, particularly for light, is often assumed to producethis result. Using a long-term dataset from North Americanherbaceous plant communities, we tested whether heightand clonal growth form together predict responses to fertilizationbecause neither trait alone predicted species loss in aprevious analysis. Species with a tall-runner growth formcommonly increased in relative abundance in response toadded nitrogen, while short species and those with a tallclumpedclonal growth form often decreased. The ability toincrease in size via vegetative spread across space, whilesimultaneously occupying the canopy, conferred competitiveadvantage, although typically only the abundance of a singlespecies within each height-clonal growth form significantlyresponded to fertilization in each experiment. Classifyingspecies on the basis of two traits (height and clonal growthform) increases our ability to predict species responses tofertilization compared to either trait alone in predominantlyherbaceous plant communities.},
keywords = {ARC, clonal growth, competition, GCE, grassland, KNZ, nitrogen addition, productivity},
doi = {10.1007/s00442-012-2264-5},
author = {Gough, Laura and Gross, Katherine L. and Cleland, Elsa E and Clark, Christopher M. and Collins, Scott L. and Fargione, Joseph E. and Pennings, Steven C. and Suding, Katherine N.}
@article {64957,
title = {Mapping Phytoplankton Chlorophyll in Turbid, Case 2 Estuarine andCoastal Waters},
journal = {Israel Journal of Plant Sciences},
year = {2012},
abstract = {We tested variants of semianalytic algorithms for estimating phytoplankton chlorophyll pigment in Case 2 waters. Since 2002 we sampled 279 stations in 22 estuaries, bays and near shore at seven National Estuarine Research Reserves between Delaware and Texas (USA). The following median values and ranges were observed: chlorophyll a = 17.4 \&$\#$61549;g/L3 (0.2},
keywords = {chlorophyll a, coastal, estuarine, GCE, mapping, phytoplankton, remote sensing},
author = {Schalles, John F. and Hladik, Christine M.}
@article {64959,
title = {Mechanisms mediating plant distributions across estuarine landscapes in a low-latitude tidal estuary},
journal = {Ecology},
volume = {93},
year = {2012},
pages = {90-100},
abstract = {Understanding of how plant communities are organized and will respond to global changes requires an understanding of how plant species respond to multiple environmental gradients. We examined the mechanisms mediating the distribution patterns of tidal marsh plants along an estuarine gradient in Georgia using a combination of field transplant experiments and monitoring. Our results could not be fully explained by the},
keywords = {biotic interaction, competition, estuary, facilitation, FLOODING, GCE, physical gradient, salinity, signature publication, zonation},
doi = {10.1890/11-0487.1},
url = {http://www.esajournals.org/doi/abs/10.1890/11-0487.1},
author = {Guo, Hongyu. and Pennings, Steven C.}
@article {80692,
title = {A meta-analysis of seaweed impacts on seagrasses: generalities and knowledge gaps},
volume = {7},
year = {2012},
abstract = {Seagrasses are important habitat-formers and ecosystem engineers that are under threat from bloom-forming seaweeds.These seaweeds have been suggested to outcompete the seagrasses, particularly when facilitated by eutrophication,causing regime shifts where green meadows and clear waters are replaced with unstable sediments, turbid waters, hypoxia,and poor habitat conditions for fishes and invertebrates. Understanding the situations under which seaweeds impactseagrasses on local patch scales can help proactive management and prevent losses at greater scales. Here, we provide aquantitative review of available published manipulative experiments (all conducted at the patch-scale), to test whichattributes of seaweeds and seagrasses (e.g., their abundances, sizes, morphology, taxonomy, attachment type, or origin)influence impacts. Weighted and unweighted meta-analyses (Hedges d metric) of 59 experiments showed generally highvariability in attribute-impact relationships. Our main significant findings were that (a) abundant seaweeds had strongernegative impacts on seagrasses than sparse seaweeds, (b) unattached and epiphytic seaweeds had stronger impacts than},
keywords = {GCE, not listed},
author = {Thomsen, M. S and Silliman, Brian R. and Wernberg, Thomas and Engelen, H. and Tuya, F. and Vanderklift, M. and Holmer, M. and McGlathery, K. and Arenas, F. and Kotta, J.}
@article {80708,
title = {Numerical models of salt marsh evolution: Ecological, geomorphic and climatic factors},
volume = {50},
year = {2012},
abstract = {Salt marshes are delicate landforms at the boundary between the sea and land. These ecosystems support a diverse biota that modifies the erosive characteristics of the substrate and mediates sediment transport processes. Here we present a broad overview of recent numerical models that quantify the formation and evolution of salt marshes under different physical and ecological drivers. In particular, we focus on the coupling between geomorphological and ecological processes and on how these feedbacks are included in predictive models of landform evolution. We describe in detail models that simulate fluxes of water, organic matter, and sediments in salt marshes. The interplay between biological and morphological processes often produces a distinct scarp between salt marshes and tidal flats. Numerical models can capture the dynamics of this boundary and the progradation or regression of the marsh in time. Tidal channels are also key features of the marsh landscape, flooding and draining the marsh platform and providing a source of sediments and nutrients to the marsh ecosystem. In recent years several numerical models have been developed to describe the morphogenesis and long-term dynamics of salt marsh channels. Finally, salt marshes are highly sensitive to the effects of long-term climatic change. We therefore discuss in detail how numerical models have been used to determine salt marsh survival under different scenarios of sea level rise.},
keywords = {climate, GCE, geomorphology, models, salt marsh},
doi = {10.1029/2011RG000359},
url = {http://www.agu.org/pubs/crossref/pip/2011RG000359.shtml},
author = {Sergio Fagherazzi
, and Reyes, Enrique and Clough, Jonathan and Kirwan, Matthew Lynn and Mudd, Simon Marius and Guntenspergen, Glenn R. and Temmerman, Stijn and D{\textquoteright}Alpaos, Andrea and van de Koppel, Johan and Craft, Christopher B. and Rybczyk, John}
@article {64972,
title = {Patch size-dependent community recovery after massive disturbance},
journal = {Ecology},
volume = {93},
year = {2012},
pages = {101},
abstract = {Massive anthropogenic and climate-related disturbances are now common in ecosystems worldwide, generating widespread die-off and subsequent community recovery dominated by remnant-patch dynamics rather than open-gap dynamics. Whether communities can recover and, if so, which factors mediate recolonization rate and extent remain unresolved. Here we evaluate recolonization dynamics of southern U.S. salt marshes that experienced extensive, drought-induced die-off of the foundation species Spartina alterniflora over the previous decade. Surveys of Georgia (USA) salt marshes showed little seedling recruitment in die-off areas but persistence of Spartina particularly in large, rather than small, remnant patches. Given this natural variation in remnant patch size, we conducted field experiments to test whether key plant-controlling biotic (grazing, plant neighbor presence) and abiotic (water availability) factors differentially impact Spartina recolonization at small and large-patch scales. In the small-patch (,1 m2) experiment in 2009, removing grazers and plant neighbors prompted dramatically higher expansion and growth of Spartina relative to controls, while adding freshwater to reduce water limitation had little effect. In contrast, large-patch (.20 m2) borders advanced significantly over the same time period regardless of grazer or neighbor removal. We continued the large-patch experiments in 2010, a year that experienced drought, and also added freshwater or salt to borders to modify ambient drought stress; overall, borders advanced less than the previous year but significantly more where neighbors were removed or freshwater added. Thus, water availability appears to mediate Spartina recovery by fueling large-patch expansion during wet summers and intensifying interspecific competition during drought. Combined, these findings suggest ecosystems can recover from massive disturbance if remnant foundation species},
keywords = {climate change, competition, drought, foundation species, GCE, georgia, herbivory, mudflats, patch dynamics, resilience, salt marshes, size-dependent recolonization processes, spartina alterniflora, succession, USA},
doi = {10.1890/11-0557.1},
url = {http://www.esajournals.org/doi/abs/10.1890/11-0557.1},
author = {Angelini, Christine. and Silliman, Brian R.}
@article {80728,
title = {Predator/prey-interactions promote decomposition of low-quality detritus},
year = {2012},
keywords = {armases, detritivory, GCE, littoraria, melampus, predation},
doi = {10.1007/s13157-012-0326-4},
author = {Ewers, Christine and Beiersdorf, Anika and Wieski, Kazimierz and Pennings, Steven C. and Zimmer, Martin}
@mastersthesis {80745,
title = {Salt Marsh Dieback: The response of Spartina alterniflora to disturbances and the consequences for marsh invertebrates},
year = {2012},
pages = {238},
school = {University of Georgia},
address = {Athens, GA},
abstract = {Spartina alterniflora is a foundation species that plays a disproportionately critical role in salt marshes, as it ameliorates chemical and physical stress to other plants and animals, provides essential habitat, protection from predators, and a source of organic matter to associated fauna. Disturbances including sudden dieback, herbivore overgrazing, and wrack deposition can lead to a loss of Spartina and thus, indirectly affect the invertebrate community. My goals were 1) to examine the effects on the invertebrate communities in 2 different geographical regions (GA, LA) and among 4 different disturbances within a region (GA), 2) to determine whether various disturbances would elicit a similar and predictable physiological response (the DMSO:DMSP ratio, and metal load) in Spartina that could be used as a sensitive and predictable indicator of stress among various disturbance types, and 3) to document the never before described long-term trajectory and patterns of recovery from sudden dieback in a Spartina and Juncus roemerianus marsh. Spartina loss in GA and LA led to similar decreases in Littoraria irrorata (periwinkle snails), but there were strong differences in the responses of infauna between the states and among years. These results suggested context-dependency in both the effect of foundation species within a geographical region and in the evaluation of the ecosystem service provided at the time of sampling. Overall and despite differing results, it was found that Spartina was ultimately important in maintaining the invertebrate communities in both states. However, within a geographical region, both the physiological response of Spartina and the indirect response of the invertebrates to Spartina loss were similar and predictable among four different disturbances. The DMSO:DMSP ratio and metal loads were increased in affected Spartina plants (often responsive in otherwise green leaves) and periwinkle snails and benthic macroinfauna (density, taxon richness, and diversity) were significantly decreased in affected areas, regardless of disturbance type. Vegetation recovery at sudden dieback is occurring slowly (on the order of a decade) via rhizomes extension from healthy areas, and thus understanding the effects to invertebrates is important, as disturbances such as these are expected to increase with climate change and anthropogenic effects.},
keywords = {benthic macroinfauna, chlorophyll a, DMSO, dmsp, foundation species, GCE, juncus roemerianus, littoraria irrorata, metals, salt marsh dieback, spartina alterniflora},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/McFarlin_Caroline_PhD_2012.pdf},
author = {McFarlin, Caroline R.}
@inbook {80758,
title = {South Atlantic Tidal Wetlands},
year = {2012},
pages = {45-61},
publisher = {University of California Press},
organization = {University of California Press},
edition = {1},
address = {Berkeley, California},
keywords = {ecology, GCE, tidal, wetlands},
url = {http://www.ucpress.edu/book.php?isbn=9780520271647},
author = {Pennings, Steven C. and Hollibaugh, James T. and Hopkinson, Charles S. and Joye, Samantha B. and Meile, Christof and Moore, Willard S. and Silliman, Brian R. and Thompson, Victor D. and Wares, John P. and Alber, Merryl and Alexander, Clark R., Jr. and Booth, Melissa G. and Burd, Adrian B. and Cai, Wei-Jun and Craft, Christopher B. and DePratter, Chester and Di Iorio, Daniela},
editor = {Baldwin, A.H.}
@article {64987,
title = {Southeastern U.S.A. continental shelf respiratory rates revisited},
journal = {Biogeochemistry},
volume = {107},
year = {2012},
pages = {501-506},
abstract = {Respiratory rates on the U. S. southeastern continental shelf have been estimated several times by different investigators, most recently by Jiang et al. (Biogeochemistry 98:101},
keywords = {bacteria, dissolved oxygen, GCE, microbial respiration, southeastern u.s.a. continental shelf},
doi = {10.1007/s10533-010-9552-0},
url = {http://www.springerlink.com/openurl.asp?genre=article\&id=doi:10.1007/s10533-010-9552-0},
author = {Sheldon, Joan E. and Griffith, Peter C. and Peters, Francesc. and Sheldon, Wade M. and Blanton, Jackson O. and Amft, Julie. and Pomeroy, Lawrence R.}
@article {80772,
title = {A three-stage symbioses forms the foundation of seagrass ecosystems},
volume = {319},
year = {2012},
pages = {321-323},
abstract = {Seagrasses evolved from terrestrial plants into marine foundation species around 100 million years ago. Their ecological success, however, remains a mystery because natural organic matter accumulation within the beds should result in toxic sediment sulfide levels. Using a meta-analysis,a field study, and a laboratory experiment, we reveal how an ancient three-stage symbiosis between seagrass, lucinid bivalves, and their sulfide-oxidizing gill bacteria reduces sulfide stress for seagrasses. We found that the bivalve},
keywords = {biomass, ecology, GCE, oxygen, seagrass, symbioses},
author = {van der Heide, Tjisse and Smolders, Alfons J. P. and van Gils, Jan A. and Govers, Laura L. and de Fouw, Jimmy and Olff, Han and van der Geest, Matthiis and van Katwijk, Marieke M. and Piersma, Theunis and van de Koppel, Johan and Silliman, Brian R.}
@mastersthesis {80779,
title = {Use of Remote Sensing Data for Evaluating Elevation and Plant Distribution in a Southeastern Salt Marsh},
year = {2012},
pages = {205},
school = {University of Georgia},
address = {Athens, GA},
abstract = {Salt marshes are valuable ecosystems that are susceptible to habitat loss due to changes in sea level and coastal flooding, and there is growing interest in obtaining accurate habitat and elevation maps for these areas. Remote sensing techniques such as Light Detection and Ranging (LIDAR) can produce digital elevation models (DEMs), but the accuracy of LIDAR in salt marshes is limited by a combination of sensor resolution, instrument errors, and poor laser penetration in dense vegetation. I assessed the accuracy of a LIDAR-derived DEM for the salt marshes surrounding Sapelo Island, GA using real time kinematic (RTK) GPS. These observations were used to develop and validate species-specific correction factors for ten marsh cover classes, which ranged from 0.03 to 0.25 m. In order to apply these corrections to the 13 km2 study site, I classified hyperspectral imagery by cover class and combined this information with elevation in a decision tree. This produced both an accurate habitat classification (nine salt marsh habitat classes were mapped with a 90\% overall accuracy) and a corrected DEM (overall mean error was reduced from 0.10},
keywords = {classification and regression trees (CART), digital elevation model (DEM), GCE, habitat mapping, hyperspectral imagery, lidar, linear discriminant analysis (LDA), LTER, remote sensing, salt marsh, sapelo island},
author = {Hladik, Christine M.}
@inbook {80785,
title = {Whispers on the Landscape},
year = {2012},
publisher = {University Press of Florida},
organization = {University Press of Florida},
keywords = {Anthropogenic Landscape, GCE, Hammock, Native American, Shellfish},
author = {Thompson, Victor D.},
editor = {Thompson, Victor D.}
@article {80796,
title = {Agricultural Conservation Practices Increase Wetland Ecosystem Services in the Glaciated Interior Plains},
volume = {21},
year = {2011},
pages = {S49},
abstract = {The Glaciated Interior Plains historically supported a broad variety of wetland types, but wetland losses, primarily due to agricultural drainage, range from 50\% to 90\% of presettlement area. Wholesale land use change has created one of the most productive agricultural regions on earth, but wetland conversion has also led to the loss of the ecosystem services they provide, particularly water quality improvement, flood de-synchronization, carbon sequestration, and support of wetland-dependent species (biodiversity). Nearly three-quarters of the Glaciated Interior Plains fall within the Mississippi River drainage basin, where the combination of extensive tile drainage and fertilizer use has produced watersheds that contribute some of the highest nitrogen yields per acre to the Mississippi River. Wetland conservation practices implemented under Farm Bill conservation programs have established or involved management of nearly 110 000 ha of wetlands, riparian zones, and associated ecosystem services over the period 2000},
keywords = {agricultural conservation, GCE, Interior Glaciated Plains, wetland ecosystem},
author = {Fennessy, S. and Craft, C. B.}
@mastersthesis {65017,
title = {Application of the Water Quality Analysis Simulation Program (WASP) to Evaluate Dissolved Nitrogen Concentrations in the Altamaha River Estuary, Georgia},
year = {2011},
pages = {227},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {The Water Quality Analysis Simulation Program (WASP v.7.4) and a water flow model, SqueezeBox, were used to model concentrations of dissolved nitrogen (DN) in the Altamaha River estuary, Georgia. Model development was guided by previous studies using WASP, literature surveys, and sensitivity analyses. The model was calibrated and validated against observations from the Georgia Coastal Ecosystems Long Term Ecological Research project. Average error between model predicted and observed concentrations was 39.8 \% for NH3, 23.6 \% for NO3-, and 7.8 \% for DON. Results from the calibrated model showed that riverine DN input had an approximately 6-fold greater influence on predicted DN in the estuary than either flow or temperature. Overall, predicted DN concentrations were highest for high DN input, high flows, and low and medium temperatures.},
keywords = {altamaha, GCE, nitrogen, wasp, water quality},
url = {http://gce-lter.marsci.uga.edu/public/uploads/GCEPub675_GKaufman_MS_2011_20120221T135921.pdf},
author = {Kaufman, Galen.}
@article {65036,
title = {A Blueprint for Blue Carbon: Towards an improved understanding of the role of vegetated coastal habitats in sequestering CO2},
journal = {Frontiers in Ecology and the Environment.},
year = {2011},
keywords = {carbon, coastal, GCE, habitat},
author = {McLeod, E. and Salman, Rebecca. and Bjork, M. and Bouillion, S. and Duarte, C. and Lovelock, C. and Silliman, Brian R.}
@article {80810,
title = {A broad framework to organize and compare invasive species impacts},
volume = {111},
year = {2011},
pages = {899-908},
abstract = {Invasive species have transformed local, regional and global biotas; however, few generalities about the mechanisms driving impacts of invaders have emerged. To explain variation in impacts among studies, we propose a broad framework that separates drivers of impacts into universal and unique attributes of the invasive species and the invaded habitat. Universal attributes are relevant to all invasions whereas unique attributes are distinct to a specific invasion. For example, impacts associated with the abundance of any invader or the properties of a specific invader (e.g., a rare toxin) represent a universal and unique impact attribute. Through meta-analyses of aquatic field experiments, we demonstrate the utility of our framework, documenting that both the abundance and the taxonomic identity of the invader significantly influence invasion outcomes for marine and freshwater plant and animal invaders. Our review also highlights that many more experiments are needed to test for universal attributes, such as priority effects, age and size, and how the attributes of the invaded habitat further modify invasion impacts. We hope that our framework will stimulate experimental invasion ecology and begin to reconcile the idiosyncrasies that currently impede the development of a unified framework for invasion impacts.},
keywords = {Field experiments, GCE, Invasions-impact, meta-analysis},
author = {Thomsen, M. S and Wernberg, T and Olden, J. and Griffin, John N. and Silliman, Brian R.}
@article {65058,
title = {Coastal Landscapes and Their Relationship to Human Settlement on the Georgia Coast},
journal = {Anthropological Papers of the American Museum of Natural History},
year = {2011},
abstract = {Local geomorphology and geology are important in understanding human settlement patterns, especially in coastal settings. We attempt to examine these issues in coastal Georgia, USA, through a campaign of vibracoring, radiocarbon and optically stimulated luminescence dating, and sediment analyses. Certain aspects of Georgia coastal geomorphology have been clarified, while at the same time new questions have been raised. One key finding is that pre-existing topography, even in dynamic coastal settings, can be important landscape components. Related is the finding that changes in the coastal landscape are not straightforward, but are significantly influenced by antecedent surfaces. This makes creation of a holistic model for coastal landscape development difficult, while at the same time complicating the retro-diction of human use of these landforms without direct archaeological and/or geomorphological data. We additionally find that new coastal landforms are rapidly utilized by humans as they naturally develop, substantiating conclusions drawn in previous studies. Finally, previous dating of coastal landforms using archaeological techniques has, for the most part, been corroborated, illustrating the complementary nature of archaeological and geological techniques.},
keywords = {archaeology, GCE, geology, grain size, land use, stratigraphy},
author = {Turck, John A. and Alexander, Clark R}
@article {65076,
title = {Crab regulation of cross-ecosystem resource transfer by marine foraging fire ants},
journal = {Oecologia},
volume = {166},
year = {2011},
pages = {1111-1119},
abstract = {Permeability of boundaries in biological systems is regulated by biotic and/or abiotic factors. Despite this knowledge, the role of biotic factors in regulating resource transfer across ecosystem boundaries has received little study. Additionally, little is known about how cross-ecosystem resource transfer affects source populations. We used experiments, observations and stable isotopes, to evaluate: (1) the proportion of intertidal-foraging black fire ant (Solenopsis richteri) diet derived from marine sources, (2) how black fire ant cross-ecosystem resource transfer is altered by the dominant bioengineer in the intertidal, a burrowing crab (Neohelice granulata), (3) the topdown impact of these terrestrial ants on a marine resource, and (4) the effect of marine resources on recipient black fire ants. We found that more than 85\% of the black fire ant diet is derived from marine sources, the number of intertidal foraging ants doubles in the absence of crab burrows, and that ants cause a 50\% reduction in intertidal polychaetes. Also, ant mound density is three times greater adjacent to marine systems. This study reveals that cross-ecosystem foraging terrestrial ants can clearly have strong impacts on marine resources. Furthermore, ecosystem engineers that modify and occupy habitat in these ecosystem boundaries can strongly regulate the degree of cross-ecosystem resource transfer and resultant top down impacts.},
keywords = {ants, crabs, ecosystem, estuarine, GCE},
doi = {10.1007/s00442-011-1952-x},
url = {http://www.springerlink.com/content/v2h80ut730h85424/},
author = {Garcia, E. A. and Bertness, Mark D. and Alberti, J. and Silliman, Brian R.}
@article {80836,
title = {Determining the Habitats of Mollusk Collection at the Sapelo Island Shell Ring Complex, USA using Oxygen Isotope Sclerochronology},
year = {2011},
keywords = {GCE, Late Archaic, Oxygen Isotope, Sclerochronology},
author = {Andrus, C. F.T. and Thompson, Victor D.}
@article {65132,
title = {Effects of five years of nitrogen and phosphorus additions on a Zizaniopsis miliacea tidal freshwater marsh.},
journal = {Aquatic Botany},
year = {2011},
pages = {17-23},
abstract = {The purpose of this experiment was to determine if nitrogen (N) or phosphorus (P) acts as the limiting nutrient for tidal freshwater marsh vegetation. To answer this question, we added N, P, and N + P to a tidal freshwater marsh dominated by Zizaniopsis miliacea (Michx.) (giant cutgrass) in Georgia, USA, for \&$\#$64257;ve years to determine their effects on aboveground and belowground biomass and nutrient (N, P) uptake. Nitrogen and P were applied twice per year at an annual rate of 50 g m\&$\#$8722;2 year\&$\#$8722;1 and 10 g m\&$\#$8722;2 year\&$\#$8722;1, respectively. Aboveground biomass and leaf C, N, and P were sampled in August of each year. Belowground biomass and C, N, and P content were measured in August of year \&$\#$64257;ve. After two years, plots receiving N and N + P had signi\&$\#$64257;cantly greater aboveground biomass than the control and P plots. This trend continued through the \&$\#$64257;fth year of the study and resulted in two to three times more aboveground biomass at the end of the \&$\#$64257;fth year in the N (1570 g m\&$\#$8722;2) and N + P (1264 g m\&$\#$8722;2) plots relative to P (710 g m\&$\#$8722;2) and control (570 g m\&$\#$8722;2) plots. After \&$\#$64257;ve years of nutrient additions, macro-organic matter (MOM), the living plus dead root and rhizome mat (0},
keywords = {aboveground biomass, belowground biomass, fertilizer, GCE, n:p ratio, nitrogen, nutrient limitation, phosphorus, pontederia cordata, sagittaria lancifolia, tidal freshwater marsh, zizaniopsis miliacea},
doi = {10.1016/j.aquabot.2011.03.003},
author = {Ket, Wes. and Schubauer-berigan, Joe. and Craft, Christopher B.}
@article {65137,
title = {Effects of Salinity on Denitrification and Greenhouse Gas Production from Laboratory-incubated Tidal Forest Soils},
journal = {Wetlands},
year = {2011},
pages = {11},
abstract = {We measured ambient and potential denitrification in tidal freshwater floodplain forest (tidal forests) soils along the Altamaha, Ogeechee, and Satilla Rivers in southeast Georgia to characterize nitrogen removal from these understudied systems. Further, we measured the response of denitrification, greenhouse gas production (CO 2 , CH 4 , N 2 O), and the formation of reduced inorganic sulfur species following laboratory incubations simulating saltwater intrusion with salinity levels of 2 and 5. Ambient denitrification ranged from 0.03},
keywords = {CH4, CO2, denitrification, GCE, greenhouse gases, salt water intrusion, tidal forests},
doi = {10.1007/s13157-012-0270-3},
author = {Marton, John. and Herbert, Ellen. and Craft, Christopher B.}
@article {65138,
title = {Effects of Sea-Level Rise and Anthropogenic Development on Priority Bird Species Habitats in Coastal Georgia, USA},
journal = {Environmental Management},
volume = {49},
year = {2011},
pages = {473-482},
abstract = {We modeled changes in area of five habitats, tidal-freshwater forest, salt marsh, maritime shrub-scrub (shrub), maritime broadleaf forest (oak) and maritime narrowleaf (pine) forest, in coastal Georgia, USA, to evaluate how simultaneous habitat loss due to predicted changes in sea level rise (SLR) and urban development will affect priority bird species of the south Atlantic coastal plain by 2100. Development rates, based on regional growth plans, were modeled at 1\% and 2.5\% annual urban growth, while SLR rates, based on the Intergovernmental Panel on Climate Change},
keywords = {birds, coast, conservation planning, GCE, GIS MODEL, land-use change, sea-level rise, urban development},
doi = {10.1007/s00267-011-9761-x},
author = {Brittain, Ross. and Craft, Christopher B.}
@inbook {80859,
title = {Estuarine and Coastal Ecosystems and Their Services},
volume = {12},
year = {2011},
pages = {109},
publisher = {Elsevier},
organization = {Elsevier},
edition = {Ecological Economics of Estuaries and Coasts},
abstract = {The global decline in estuarine and coastal ecosystems (ECEs) is affecting a number of critical benefits, or ecosystem services. We review the main ecological functions and their services across a variety of ECEs, including marshes, mangroves, nearshore coral reefs, seagrass beds, and sand beaches and dunes. We cite estimates of the key economic values arising from these services, and discuss how the natural variability of ECE impacts their benefits, the synergistic relationships of ECE across seascapes, and the management implications.},
keywords = {coral reef, Economic value, ecosystem service, Estuarine and coastal ecosystem, GCE, mangrove, salt marsh, Sand dune, seagrass, Seascape},
doi = {10.1016/B978-0-12-374711-2.01206-7},
url = {http://www.sciencedirect.com/science/article/pii/B9780123747112012067},
author = {Barbier, Edward B. and Hacker, Sally D. and Koch, Evamaria W. and Stier, A. and Silliman, Brian R.},
editor = {Costanza, R.}
@article {65149,
title = {Estuarine and Coastal Ocean Carbon Paradox: CO2 Sinks or Sites of Terrestrial Carbon Incineration?},
journal = {Annual Review of Marine Science},
volume = {3},
year = {2011},
pages = {123-145},
abstract = {Estuaries are a major boundary in the land-ocean interaction zone where organic carbon (OC) and nutrients are being processed, resulting in a high water-to-air carbon dioxide (CO2) flux (0.25 Pg C y\&$\#$8722;1). The continental shelves, however, take up CO2 (0.25 Pg C y\&$\#$8722;1) from the atmosphere, accounting for approximately 17\% of open ocean CO2 uptake (1.5 Pg C y\&$\#$8722;1). It is demonstrated here that CO2 release in estuaries is largely supported by microbial decomposition of highly productive intertidal marsh biomass. It appears that riverine OC, however, would bypass the estuarine zone, because of short river-transit times, and contribute to carbon cycling in the ocean margins and interiors. Low-latitude ocean margins release CO2 because they receive two-thirds of the terrestrial OC. Because of recent CO2 increase in the atmosphere, CO2 releases from low latitudes have become weaker and CO2 uptake by mid- and high-latitude shelves has become stronger, thus leading to more dissolved inorganic carbon export to the ocean.},
keywords = {carbon, estuarine, GCE, signature publication, sinks, terrestrial carbon incineration},
doi = {10.1146/annurev-marine-120709-142723},
url = {http://www.annualreviews.org/doi/abs/10.1146/annurev-marine-120709-142723?prevSearch=wei-jun\%2Bcai\&searchHistoryKey=},
author = {Cai, Wei-Jun.}
@article {65150,
title = {Evaluating Mobility, Monumentality, and Feasting at the Sapelo Island Shell Ring Complex},
journal = {American Antiquity},
volume = {76},
year = {2011},
pages = {315-343},
abstract = {wo of the most salient anthropological questions regarding southeastern shell ring sites are related to the season(s) that they were occupied and whether or not the deposits represent monumental constructions and/or feasting remains. This paper addresses these questions through the analysis of growth band of clams (Mercenaria spp.) (N = 620) and stable oxygen isotope ratios of clam and oyster shells (Crassostrea virginica) (N = 58) at the Sapelo Island Shell Ring complex located on the Georgia coast, USA. The season of death and the samples {\textquoteright}position in the shell matrix at Sapelo provide important information on the rate of shell deposition and the season(s) the site was occupied. These data support the view that at least some portion of the human population at Sapelo occupied the site year-round. Additionally, while it appears that two shell rings at the site formed through the gradual deposition and accumulation of daily subsistence, other areas evidence short term, large-scale, shellfish processing and may lend credence to the view that at some point shell rings become monuments, commemorating rituals and gatherings.},
keywords = {GCE, mobility, monumentality, sapelo, shell},
author = {Thompson, Victor D. and Andrus, C. F.T.}
@article {65160,
title = {Field measurements and modeling of groundwater flow and biogeochemistry at Moses Hammock, a backbarrier island on the Georgia coast},
journal = {Biogeochemistry},
volume = {104},
year = {2011},
pages = {69-90},
abstract = {A combination of field measurements, laboratory experiments and model simulations were used to characterize the groundwater biogeochemical dynamics along a shallow monitoring well transect on a coastal hammock. A switch in the redox status of the dissolved inorganic nitrogen (DIN) pool in the well at the upland/saltmarsh interface occurred over the spring-neap tidal transition: the DIN pool was dominated by nitrate during spring tide and by ammonium during neap tide. A density-dependent reaction-transport model was used to investigate the relative importance of individual processes to the observed N redox-switch. The observed N redox-switch was evaluated with regard to the roles of nitrification, denitrification, dissimilatory nitrate reduction to ammonium (DNRA), ammonium adsorption, and variations in inflowing water geochemistry between spring and neap tides.Transport was driven by measured pressure heads and process parameterizations were derived from field observations, targeted laboratory experiments, and the literature. Modeling results suggest that the variation in inflow water chemistry was the dominant driver of DIN dynamics and highlight the importance of spring-neap tide variations in the high marsh, which influences groundwater biogeochemistry at the marsh-upland transition.},
keywords = {GCE, hammock groundwater, nitrogen cycle, reaction transport modeling, signature publication, spring-neap tide cycle, upland-marsh transition},
doi = {10.1007/s10533-010-9484-8},
url = {http://www.springerlink.com/content/t18x02358tt6x123/},
author = {Porubsky, William P. and Joye, Samantha B. and Moore, Willard S. and Tuncay, Kagan. and Meile, Christof.}
@article {65174,
title = {A framework to study the context-dependent impacts of marine invasions},
journal = {Journal of Experimental Marine Biology and Ecology},
volume = {400},
year = {2011},
pages = {322-327},
abstract = {The ecological impacts of marine invasive species vary according to the spatial and temporal scale of analysis, thereby challenging the extraction of generalities about underlying mechanisms. Here, we applied a broad impact framework that addresses this scale-dependency, to test if general drivers of impacts can be identified and quantified from marine invasion experiments. This framework explains variability in impacts according to the unique (specific) and universal (general) attributes of the (1) invasive organism, (2) resident biota, (3) resource levels, and (4) abiotic conditions. In this framework, unique and universal attributes encompass the properties that are either ecologically relevant to only a few specific invasions (e.g. a unique toxin) or to most invasions (e.g. invader density, size, age or longevity), respectively. We reviewed 88 published marine invasion impact experiments, where 18 tested for effects of universal and 11 for unique attributes of the invasive organism (63 tested for presence.absence effects, where these attributes are confounded). A meta-analysis confirmed that the species identity and density (representing a unique and universal attribute, respectively) of the invader significantly predicted impacts. These attributes should, therefore, whenever possible, be treated as separate impact-modifiers. By contrast, very few experiments have tested if universal or unique attributes of the resident biota, the resource levels or the abiotic conditions modify invasion impact. This highlights a major research gap; quantitative syntheses cannot be undertaken until more factorial experiments have manipulated the invasive species and habitat-associated drivers in concert (with .2 treatments per test factor). In conclusion, to facilitate a broader understanding of marine invasion impacts, we advocate that universal and unique impact-components, whenever possible, are treated as separate test entities that should be examined for each of the four impact drivers.},
keywords = {GCE, impact, invasion, marine},
doi = {10.1016/j.jembe.2011.02.033},
url = {http://www.sciencedirect.com/science/article/pii/S0022098111000815},
author = {Thomsen, Mads S. and Wernberg, T and Olecki, Paula. and Griffin, John. and Silliman, Brian R.}
@article {80870,
title = {Genetic structure comparisons illuminate connectivity patterns in Caribbean gastropods},
year = {2011},
keywords = {GCE, None listed},
author = {Diaz-Ferguson, Edgardo and Haney, A. and Wares, John P. and Silliman, Brian R.}
@mastersthesis {65177,
title = {Geoarchaeological analysis of two back-barrier islands and their relationship to the changing landscape of coastal Georgia, U.S.A.},
year = {2011},
pages = {239},
school = {University of Georgia},
address = {Athens, GA},
abstract = {This study examines the past human settlement system on the coast of Georgia from 12,000-1,000 B.P. (the Paleoindian through Late Woodland periods) in relation to landscape change. I take a landscape approach to understanding settlement, incorporating geomorphology, formation processes, a distributional approach to archaeological data, and landscape ecology metrics. Archaeological surveys of two back-barrier islands, Mary Hammock (9MC351) and Patterson Island (9MC493), are combined with non-archaeological paleoenvironmental data, and compared to changes in sea level, and to archaeological surveys from other environmental settings, to understand the change in human occupation in McIntosh County, GA. Numerous environmental datasets, including present-day elevations, former surfaces under the marsh, bathymetric data, soils, and wetlands, were incorporated together. These data were combined with changes in sea level over time, creating a dynamic model of landscape change. This model is used to create predictions about human settlement patterns in relation to the marsh-estuarine system for McIntosh County in general, and the back-barrier area specifically. These predictions were then tested with prehistoric site distributions of McIntosh County, as well as to prehistoric sherd densities of various surveys. Analysis revealed that terminal Middle Archaic sites (~5,000 B.P.) with evidence of coastal adaptations should be found within present-day McIntosh County. Because there are no such sites, I suggest that there may have been an abandonment of the coast at this time. The explosion in Late Archaic sites, then, may have been from an influx of people to the Georgia coast. Back-barrier islands were always part of the settlement system. The intensity of back-barrier island utilization may be related to their proximity to larger landmasses (the mainland and major barrier islands), and the different types of settlement systems associated with those landmasses. The intense utilization of back-barrier islands at certain times suggests that they may have been permanently settled. Another explanation for their intense use may be that these are relatively small islands where activities would have been concentrated. The predictions of the model were not always substantiated, indicating that changes in sea level and marsh-estuarine resources were not the only reason for changes in settlement and subsistence patterns.},
keywords = {archaeology, back-barrier, GCE, geomorphology, Islands, landscape change, marsh, mary hammock, patterson island, sea level, settlement patterns},
url = {http://gce-lter.marsci.uga.edu/public/uploads/GCEPub667_Turck_PhD_2011_20120125T93415.pdf},
author = {Turck, John A.}
@mastersthesis {65179,
title = {Geographic Variation in the Structure of Salt Marsh Arthropod Communities},
year = {2011},
pages = {51},
school = {University of Houston},
address = {Houston, Texas},
abstract = {The natural environment shows variation at multiple scales, and determining how large-scale patterns relate to the local community{\textquoteright}s structure and function is a fundamental goal of ecology. Salt marshes along the Atlantic and Gulf coasts are similar in many ways, and are inhabited by the same plant and insect species. However, the Atlantic and Gulf coast areas have different tidal regimes, which may result in the two areas not functioning exactly the same. In addition, abiotic factors that vary with latitude or longitude may lead to differences between northern and southern or eastern and western sites. I hypothesized that structure and function of the coastal salt marsh varies geographically. To test this, I characterized abiotic conditions and the plant and arthropod communities at 11 sites along each coast in the late summers of 2009 and 2010. I also manipulated wrack (dead plant stems) and nutrient availability in 2 x 3 m plots at each site to evaluate geographic differences in community response. The experiment was established in 2009 and allowed to run to 2010. My sampling documented that some abiotic factors varied geographically, as did plant height, nitrogen content, and thatch cover. Although the total number of arthropods collected did not differ geographically, the trophic composition of samples showed marked variation among regions. Large-scale differences in latitude and mean tidal range are likely driving much of this variation. Arthropod community structure was little affected by wrack addition, but responded strongly to fertilization; and, the effect of fertilization varied geographically for some trophic levels. Although salt marshes are superficially similar from Maine to Texas, they may be structured differently throughout this geographic range. Therefore, extrapolating results from one geographic region to another should be done with caution.},
keywords = {arthropod, community ecology, GCE, geography, salt marsh},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/BMcCall_MS_Thesis_2011.pdf},
author = {McCall, Brittany DeLoach.}
@article {65190,
title = {Guest Editorial: When teachers become scientists},
journal = {Science Scope},
year = {2011},
pages = {3},
abstract = {Ask yourself this question: Have you ever worked on a real scientific experiment? Your thoughts may jump to the lab components of your undergraduate science courses and the research papers/assignments you completed in college, but should such structured, step-by-step exercises really be considered experiments? Is this what real scientists do? For the author, the answer to these questions about the true nature of science came in the form of two inspirational professional development courses where teachers become scientists. In this article, she describes her participation in the workshops and discusses how these experiences benefited her students back in the classroom as well.},
keywords = {GCE, process standards for professional development},
url = {http://learningcenter.nsta.org/product_detail.aspx?id=10.2505/4/ss11_034_06_6},
author = {Linsky, Catherine L.}
@article {65193,
title = {Habitat use by coastal birds inferred from stable carbon and nitrogen isotopes},
journal = {Estuaries and Coasts},
year = {2011},
abstract = {Conservationists need to know the degree of habitat fidelity for species of conservation concern. Stable Isotope Analysis in R quantified the contribution of terrestrial vs. saltmarsh primary production sources to terrestrial passerine food webs from four habitats of Sapelo Island, Georgia (USA), saltmarsh, maritime scrub},
keywords = {carbon-13, food web, GCE, nitrogen-15, saltmarsh, siar, stable isotopes},
doi = {10.1007/s12237-011-9446-y},
author = {Brittain, Ross. and Schimmelmann, A. and Parkhurst, David F. and Craft, Christopher B.}
@article {65230,
title = {Interactions among foundation species underlie community organization},
journal = {BioScience},
year = {2011},
keywords = {community, GCE, interactions, species},
author = {Angelini, Christine. and Alteiri, A. and Silliman, Brian R. and Bertness, Mark D.}
@article {65246,
title = {Latitudinal variation in top-down and bottom-up control of a salt marsh food web},
journal = {Ecology},
volume = {92},
year = {2011},
pages = {276-281},
abstract = {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},
keywords = {bottom-up, GCE, herbivory, iva, latitude, predation, top-down},
doi = {10.1890/10-0760.1},
url = {http://www.esajournals.org/doi/abs/10.1890/10-0760.1},
author = {Marczak, Laurie. and Ho, Chuan-Kai. and Vu, Huy. and Denno, Robert. and Pennings, Steven C.}
@article {65267,
title = {Metatranscriptomic analysis of ammonia-oxidizing organisms in an estuarine bacterioplankton assemblage},
journal = {ISME Journal},
volume = {5},
year = {2011},
pages = {866-878},
abstract = {Quantitative PCR (qPCR) analysis revealed elevated relative abundance (1.8\% of prokaryotes) of marine group 1 Crenarchaeota (MG1C) in two samples of southeastern US coastal bacterioplankton, collected in August 2008, compared with samples collected from the same site at different times (mean 0.026\%). We analyzed the MG1C sequences in metatranscriptomes from these samples to gain an insight into the metabolism of MG1C population growing in the environment, and for comparison with ammonia-oxidizing bacteria (AOB) in the same samples. Assemblies revealed low diversity within sequences assigned to most individual MG1C open reading frames (ORFs) and high homology with},
keywords = {ammmonia oxidation, crenarchaeota, GCE, nitrosococcus, nitrosomonas, nitrosopumilus, nitrosospira, signature publication},
doi = {10.1038/ismej.2010.172},
url = {http://www.nature.com/ismej/journal/vaop/ncurrent/abs/ismej2010172a.html},
author = {Hollibaugh, James T. and Gifford, Scott. and Sharma, S. and Bano, Nasreen. and Moran, Mary Ann.}
@mastersthesis {65269,
title = {Microbial Ecology and Biogeochemistry of the Coastal Ocean: New Insights from Metatranscriptomics},
year = {2011},
pages = {163},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {In the oceans, the transfer of energy and cycling of elements is predominantly controlled by bacterioplankton, such that any understanding of marine ecosystems requires knowledge about bacterial activities and functional capabilities. Metatranscriptomics, the direct retrieval and sequencing of environmental RNA, is a powerful tool that can identify active community members and their expressed functional capabilities. This dissertation is composed of three studies that used metatranscriptomics to gain fundamental insights into the ecology and biogeochemistry of coastal microbial communities. In the first study, an internal standard approach was developed to make absolute (per liter) estimates of transcript numbers, a significant advantage over proportional estimates. Expression levels of genes diagnostic for transformations in the marine nitrogen, phosphorus and sulfur cycles were determined, as well as the total size of the mRNA pool. By representing expression in absolute units, metatranscriptomics extends beyond relative comparisons, allowing for direct comparisons with other biogeochemical measurements. In the second study, a metatranscriptomic dataset revealed an unexpected abundance of transcripts to Candidatus Nitrosopumilus maritimus, an ammonia oxidizing Archaea whose presence has significant implications in the carbon and nitrogen cycles. Reads assigned to genes for ammonia uptake and oxidation accounted for 37\% of N. maritimus transcripts. In contrast, transcripts from co-occurring ammonia oxidixing Bacteria were in much lower abundance, with no transcripts related to ammonia oxidation or carbon fixation. This study suggests that these two members of the ammonia oxidizing functional guild respond differently to the same environmental cues. The third study used metatranscriptomics to examine how differences in expression among taxa can be indicative of niche diversification. The sequencing of transcripts from four coastal bacterial communities revealed the expression and activity of thousands of different taxa. The genes carried by these taxa have extensive overlap, and the majority of highly expressed genes were for redundant functions. To identify unique ecological roles for these taxa, a method was developed to classify genes both by their expression level and their frequency in genomes. The results show clear functional delineations across broad phylogenetic groupings and provide insights into the diversity of lifestyle strategies that supports complex microbial assemblages.},
keywords = {biogeochemistry, dna, GCE, genomics, metatranscriptomics, microbes, microbial ecology, molecular, ocean, rna},
url = {http://gce-lter.marsci.uga.edu/public/uploads/GCEPub687_Gifford_PhD_2011_20120125T92748.pdf},
author = {Gifford, Scott.}
@article {65282,
title = {New metrics for managing and sustaining the ocean},
journal = {Marine Policy},
year = {2011},
abstract = {Policies are arising around the world, most recently in the United States, that mandate the implementation of marine spatial planning as a practical pathway towards ecosystem-based management. In the new United States ocean policy, and several other cases around the globe, ecosystem services are at the core of marine spatial planning, but there is little guidance on how ecosystem services should be measured, making it hard to implement this new approach. A new framework is shown here for practical, rigorous ecosystem service measurement that high lights contributions from both natural and social systems. The novel three-step framework addresses traditional shortcomings of an ecosystem services approach by giving managers and scientists the tools to assess and track: (1) the condition of the ecosystem (supply metrics),(2)the amount of ocean resources actually used or enjoyed by people (service metrics), and (3) people{\textquoteright}s preference for that level of service (value metrics). This framework will allow real world progress on marine spatial planning to happen quickly, and with a greater chance for success.},
keywords = {GCE, manage, metrics, ocean, sustain},
doi = {10.1016/j.marpol.2011.03.013},
url = {http://www.cmsp.noaa.gov/_pdf/New_Ocean_Metrics_MarPolicy_2011_online.pdf},
author = {Tallis, H. and Copps, S. and Fox, D. and Fujita, R. and Gaines, S.D. and Gelfenbaum, G. and Gold, B. and Kareiva, P. and Kim, C. and Lee, K. and Papenfus, M. and Lester, S.E. and Redman, S. and Silliman, Brian R. and Wainger, L. and White, C. and Ruckelshaus, M. and Plummer, M. and McLeod, K. and Guerry, A. and Andelman, S. and Caldwell, M. and Conte, M.}
@article {65290,
title = {Nutrient Budgeter: A MATLAB-based program to simplify the calculation of watershed nitrogen and phosphorus budgets},
journal = {Environmental Modelling and Software},
year = {2011},
keywords = {GCE, matlab, nutrients, watersheds},
author = {Schaefer, Sylvia C. and Alber, Merryl.}
@article {65298,
title = {Patch-size dependent community recovery post- disturbance},
journal = {Ecology},
year = {2011},
abstract = {Massive anthropogenic and climate-related disturbances are now common in ecosystems worldwide, generating widespread die-off and subsequent community recovery dominated by remnant patch, rather than open gap, dynamics. Whether communities can recover and, if so, which factors mediate recolonization rate and extent remain unresolved. Here we evaluate recolonization dynamics of southern US salt marshes that experienced extensive, drought-induced die-off of the foundation species Spartina alterniflora over the previous decade. Surveys of Georgia salt marshes showed little seedling recruitment in die-off areas but persistence of Spartina particularly in large, rather than small, remnant patches. Given this natural variation in remnant patch size, we conducted field experiments to test whether key plant-controlling biotic (grazing, plant neighbor presence) and abiotic (water availability) factors differentially impact Spartina recolonization at small and large patch scales. In the small patch (<1m2) experiment, removing grazers and plant neighbors prompted dramatically higher expansion and growth of Spartina relative to controls in 2009, while adding freshwater to reduce water limitation had little effect. In contrast, large patch (>20m2) borders advanced significantly over the same time period regardless of grazer or neighbor removal. We continued the large patch experiments in 2010, a year that experienced drought, and also added freshwater or salt to borders to modify ambient drought stress: overall, borders advanced less than the previous year but significantly more where neighbors were removed or freshwater added. Thus, water availability appears to mediate Spartina recovery by fueling large patch expansion during wet summers and intensifying interspecific competition during drought. Combined, these findings suggest ecosystems can recover from massive disturbance if remnant foundation species},
keywords = {competition, drought, foundation species, GCE, herbivory, patch dynamics, resilience},
author = {Angelini, Christine. and Silliman, Brian R.}
@article {65321,
title = {Predator diversity stabilizes and strengthens trophic control of a keystone grazer},
journal = {Biology Letters},
volume = {7},
year = {2011},
pages = {79-82},
abstract = {Despite the global vulnerability of predators to extinction, and the critical functional role they play in many ecosystems, there have been few realistic tests of the consequences of predator species deletion (conversely, predator diversity) in natural ecosystems. We performed a four-month field experiment in a southeastern United States salt marsh to test the role of predatory crab diversity in regulating populations of a keystone grazer that can decimate marsh vegetation at high densities. Our results revealed that a combination of this system{\textquoteright}s two resident predator species, in comparison to individual species, both stabilize and strengthen predation rates on the potent grazer. Monthly monitoring of predation rates from intense, hot summer months into the cooler autumn indicate this diversity benefit arises from predators responding differentially to changing environmental conditions across seasons. This study provides some of the first experimental field support for the insurance hypothesis from marine ecosystems, suggests that predator temporal complementarity may be more common than currently perceived, and argues for conservation of predator diversity to ensure reliable and effective control of potentially habitat-destroying grazers.},
keywords = {diversity, GCE, keystone, predator, trophic},
doi = {10.1098/rsbl.2010.0626},
url = {http://rsbl.royalsocietypublishing.org/content/7/1/79.short},
author = {Griffin, John. and Silliman, Brian R.}
@article {80935,
title = {Predator diversity stabilizes and strengthens trophic control of a keystone grazer},
volume = {7},
year = {2011},
pages = {79-82},
abstract = {Despite the global vulnerability of predators to extinction, and the critical functional role they play in many ecosystems, there have been few realistic tests of the consequences of predator species deletion (conversely, predator diversity) in natural ecosystems. We performed a fourmonth field experiment in a southeastern United States salt marsh to test the role of predatory crab diversity in regulating populations of a keystone grazer that can decimate marsh vegetation at high densities. Our results revealed that a combination of this system},
keywords = {biodiversity, GCE, insurance hypothesis, temporal complementarity},
author = {Griffin, John N. and Silliman, Brian R.}
@article {65323,
title = {The present and future role of coastal wetland vegetation in protecting shorelines: answering recent challenges to the paradigm},
journal = {Climatic Change},
volume = {106},
year = {2011},
pages = {7-29},
publisher = {Springer Netherlands},
abstract = {For more than a century, coastal wetlands have been recognized for their ability to stabilize shorelines and protect coastal communities. However, this paradigm has recently been called into question by small-scale experimental evidence. Here, we conduct a literature review and a small meta-analysis of wave attenuation data, and we find overwhelming evidence in support of established theory. Our review suggests that mangrove and salt marsh vegetation afford context-dependent protection from erosion, storm surge, and potentially small tsunami waves. In biophysical models, field tests, and natural experiments, the presence of wetlands reduces wave heights, property damage, and human deaths. Meta-analysis of wave attenuation by vegetated and unvegetated wetland sites highlights the critical role of vegetation in attenuating waves. Although we find coastal wetland vegetation to be an effective shoreline buffer, wetlands cannot protect shorelines in all locations or scenarios; indeed large-scale regional erosion, river meandering, and large tsunami waves and storm surges can overwhelm the attenuation effect of vegetation. However, due to a nonlinear relationship between wave attenuation and wetland size, even small wetlands afford substantial protection from waves. Combining man-made structures with wetlands in ways that mimic nature is likely to increase coastal protection. Oyster domes, for example, can be used in combination with natural wetlands to protect shorelines and restore critical fishery habitat. Finally, coastal wetland vegetation modifies shorelines in ways (e.g. peat accretion) that increase shoreline integrity over long timescales and thus provides a lasting coastal adaptation measure that can protect shorelines against accelerated sea level rise and more frequent storm inundation. We conclude that the shoreline protection paradigm still stands, but that gaps remain in our knowledge about the mechanistic and context-dependent aspects of shoreline protection.},
keywords = {earth and environmental science, GCE, VCR},
doi = {10.1007/s10584-010-0003-7},
url = {http://dx.doi.org/10.1007/s10584-010-0003-7 DO - 10.1007/s10584-010-0003-7},
author = {Gedan, Keryn. and Kirwan, Matthew. and Wolanski, Eric. and Barbier, Edward. and Silliman, Brian R.}
@article {80936,
title = {The present and future role of coastal wetland vegetation in protecting shorelines: answering recent challenges to the paradigm},
volume = {106},
year = {2011},
pages = {7-29},
abstract = {For more than a century, coastal wetlands have been recognized for their ability to stabilize shorelines and protect coastal communities. However, this paradigm has recently been called into question by small-scale experimental evidence. Here, we conduct a literature review and a small meta-analysis of wave attenuation data, and we find overwhelming evidence in support of established theory. Our review suggests that mangrove and salt marsh vegetation afford context-dependent protection from erosion, storm surge, and potentially small tsunami waves. In biophysical models, field tests, and natural experiments, the presence of wetlands reduces wave heights, property damage, and human deaths. Meta-analysis of wave attenuation by vegetated and unvegetated wetland sites highlights the critical role of vegetation in attenuating waves. Although we find coastal wetland vegetation to be an effective shoreline buffer, wetlands cannot protect shorelines in all locations or scenarios; indeed large-scale regional erosion, river meandering, and large tsunami waves and storm surges can overwhelm the attenuation effect of vegetation. However, due to a nonlinear relationship between wave attenuation and wetland size, even small wetlands afford substantial protection from waves. Combining man-made structures with wetlands in ways that mimic nature is likely to increase coastal protection. Oyster domes, for example, can be used in combination with natural wetlands to protect shorelines and restore critical fishery habitat. Finally, coastal wetland vegetation modifies shorelines in ways (e.g. peat accretion) that increase shoreline integrity over long timescales and thus provides a lasting coastal adaptation measure that can protect shorelines against accelerated sea level rise and more frequent storm inundation. We conclude that the shoreline protection paradigm still stands, but that gaps remain in our knowledge about the mechanistic and context-dependent aspects of shoreline protection.},
keywords = {coastal, GCE, protection, shoreline, wetland},
url = {http://www.springerlink.com/content/k200735m7g521p67/},
author = {Bromberg-Gedan, Keryn and Kirwan, M. and Barbier, Edward B. and Wolanski, Eric and Silliman, Brian R.}
@article {65329,
title = {Quantitative analysis of a deeply sequenced marine microbial metatranscriptome},
journal = {International Society for Microbial Ecology},
volume = {5},
year = {2011},
pages = {462-472},
abstract = {The potential of metatranscriptomic sequencing to provide insights into the environmental factors that regulate microbial activities depends on how fully the sequence libraries capture community expression (that is, sample-sequencing depth and coverage depth), and the sensitivity with which expression differences between communities can be detected (that is, statistical power for hypothesis testing). In this study, we use an internal standard approach to make absolute (perliter) estimates of transcript numbers, a significant advantage over proportional estimates that can be biased by expression changes in unrelated genes. Coastal waters of the southeastern United States contain 1x10^12 bacterioplankton mRNA molecules per liter of seawater (~200 mRNA molecules per bacterial cell). Even for the large bacterioplankton libraries obtained in this study (~500 000 possible protein-encoding sequences in each of two libraries after discarding rRNAs andsmall RNAs from 41 million 454 FLX pyrosequencing reads), sample-sequencing depth was only 0.00001\%. Expression levels of 82 genes diagnostic for transformations in the marine nitrogen, phosphorus and sulfur cycles ranged from below detection (<1x10^6 transcripts per liter) for 36 genes (for example, phosphonate metabolism gene phnH, dissimilatory nitrate reductase subunitnapA) to >2.7x10^9 transcripts per liter (ammonia transporter amt and ammonia monooxygenase subunit amoC). Half of the categories for which expression was detected, however, had too few copy numbers for robust statistical resolution, as would be required for comparative (experimental or time-series) expression studies. By representing whole community gene abundance and expressionin absolute units (per volume or mass of environment),},
keywords = {bacterioplankton, biogeochemistry, GCE, gene expression, marine, metatranscriptomics},
doi = {10.1038/ismej.2010.141},
url = {http://www.nature.com/ismej/journal/vaop/ncurrent/full/ismej2010172a.html},
author = {Gifford, Scott. and Sharma, S. and Rinta-Kanto, J.M. and Moran, Mary Ann.}
@article {80942,
title = {Relationships between vegetation and environmental factors in newly formed tidal marshes of the Yangtze River estuary},
volume = {19},
year = {2011},
pages = {341-349},
abstract = {The Yangtze River delta is characterized by rapidly accreting sediments that form tidal flats that are quickly colonized by emergent vegetation including Scirpus mariqueter and the invasive species Spartina alterniflora. We measured soil surface elevation, water table depth, soil salinity, water content and compaction in the tidal flat, the Scirpus and Spartina zones and their borders to identify relationships between environmental factors and colonization by Scirpus and Spartina. With increasing elevation from tidal flat to Spartina, inundation frequency and duration, moisture and depth to water table decreased whereas soil salinity, temperature and compaction increased. High soil moisture and groundwater and low salinity were the characteristics of the tidal flat and its border with Scirpus. The Spartina zone and its border with Scirpus were characterized by greater salinity and elevation relative to the other zones. Our findings suggest that soil salinity controls patterns of plant zonation in the newly formed tidal salt marshes whereas elevation is of secondary importance. Our results suggest that patterns of vegetation zonation in tidal marshes of the Yangtze River delta are controlled by environmental factors, especially (low) salinity that favors colonization by Scirpus in the lower elevations of the marsh.},
keywords = {environmental factors, GCE, tidal marshes, Yangtze River},
author = {He, Y. and Li, X. and Craft, C. and Ma, Z. and Sun, Y.}
@article {80947,
title = {Resource Partitioning and why it matters},
volume = {2},
year = {2011},
pages = {8},
keywords = {GCE, None listed},
url = {http://www.nature.com/scitable/knowledge/library/resource-partitioning-and-why-it-matters-17362658},
author = {Griffin, John N. and Silliman, Brian R.}
@mastersthesis {65363,
title = {Smouldering oceans: on the photochemically mediated oxidation of dissolved organic matter in coastal waters},
year = {2011},
pages = {194},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {Marine dissolved organic carbon (DOC) is one of the largest and most dynamic pools of reduced carbon on earth. Photochemical processes have the potential to significantly affect the content of this DOC pool. Photochemical oxidation to carbon monoxide and carbon dioxide are two direct pathways for the removal of DOC from the marine system. Indirectly, photochemical processes can lead to the removal of DOC through the alteration of chemical structures rendering them more biologically labile. In order to assess the influence of photochemistry on the coastal carbon cycle the variability of these processes must be well constrained. To calculate photochemical production in marine waters, it is crucial to know how light is absorbed by chromophoric dissolved organic matter (CDOM), as well as the spectral efficiency of the resulting photochemical reactions (i.e. the apparent quantum yield (AQY) spectra). The challenges of using visible wavelength CDOM absorption data to model ultraviolet absorption data are investigated. Direct measurements of ultraviolet absorption data model photochemical processes best. When this is not possible, visible data can be used with an accuracy of +/- 10\% in coastal waters. Either a hyperbolic absorption model or one using correction factors applied to a traditional exponential model will allow for similar accuracy in the ultraviolet portion of the absorption spectrum. The variability of photochemical oxidation of dissolved organic carbon in a coastal system was studied in order to constrain remote sensing calculations. The variability of CO and CO2 AQY spectra were relatively well constrained in three estuaries of Georgia, USA. The AQY for CO varied within +/- 12.7\% year-round while CO2 varied within +/- 33.6\% year-round. Hyperspectral remote sensing reveals finescale hydrodynamic structure in estuarine systems and is readily adaptable to photochemical modeling applications. Defining the variability of photochemistry?s influence on the biological lability of DOC is a complex undertaking. Unlike direct photochemical oxidation of DOC to CO and CO2, the biologically labile products (BLPs) of incomplete oxidation can themselves be photochemically reactive. Competition between production and destruction of BLPs during irradiation is a significant consideration when determining the quantitative influence of photochemistry on marine systems.},
keywords = {biological lability, carbon dioxide, carbon monoxide, Chromophoric Dissolved Organic Matter, dissolved organic carbon, estuaries, GCE, photochemistry, remote sensing},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/HReader_PhD_2011.pdf},
author = {Reader, Heather E.}
@article {65393,
title = {Top-predators suppress rather than facilitate plants in a trait-mediated tri-trophic cascade},
journal = {Biology Letters},
year = {2011},
keywords = {cascade, GCE, top-predator, tropic},
author = {Griffin, John. and Brun, K. and Soomsdat, Nicole. and Butler, Jack. and Silliman, Brian R.}
@article {65396,
title = {Trophic cascades across diverse plant ecosystems},
journal = {Nature Education Knowledge},
year = {2011},
keywords = {ecosystems, GCE, trophic},
author = {Silliman, Brian R. and Holdredge, Christine.}
@article {65412,
title = {The Value of Estuarine and Coastal Ecosystem Services},
journal = {Ecological Monographs},
volume = {81},
year = {2011},
pages = {169-193},
abstract = {The global decline in estuarine and coastal ecosystems (ECEs) is affecting a number of critical benefits, or ecosystem services. We review the main ecological services across a variety of ECEs, including marshes, mangroves, nearshore coral reefs, seagrass beds, and sand beaches and dunes. Where possible, we indicate estimates of the key economic values arising from these services, and discuss how the natural variability of ECEs impacts their benefits, the synergistic relationships of ECEs across seascapes, and management implications. Although reliable valuation estimates are beginning to emerge for the key services of some ECEs, such as coral reefs, salt marshes, and mangroves, many of the important benefits of seagrass beds and sand dunes and beaches have not been assessed properly. Even for coral reefs, marshes, and mangroves, important ecological services have yet to be valued reliably, such as cross-ecosystem nutrient transfer (coral reefs), erosion control (marshes), and pollution control (mangroves). An important issue for valuing certain ECE services, such as coastal protection and habitat},
keywords = {coastal, ecosystem services, estuarine, GCE},
doi = {10.1890/10-1510.1},
url = {http://www.esajournals.org/doi/pdf/10.1890/10-1510.1},
author = {Barbier, Edward B. and Hacker, Sally D. and Koch, Evamaria W. and Stier, A. and Silliman, Brian R.}
@article {65428,
title = {Abiotic stress mediates top-down and bottom-up control in a Southwestern Atlantic salt marsh},
journal = {Oecologia},
volume = {163},
year = {2010},
pages = {181-191},
abstract = {Increasing evidence has shown that nutrients and consumers interact to control primary productivity in natural systems, but how abiotic stress affects this interaction is unclear. Moreover, while herbivores can strongly impact zonation patterns in a variety of systems, there are few examples of this in salt marshes. We evaluated the effect of nutrients and herbivores on the productivity and distribution of the cordgrass Spartina densiflora along an intertidal stress gradient, in a Southwestern Atlantic salt marsh. We characterized abiotic stresses (salinity, ammonium concentration, and anoxia) and manipulated nutrients and the presence of the herbivorous crab Neohelice (Chasmagnathus) granulata, at different tidal heights with a factorial experiment. Abiotic stress increased at both ends of the tidal gradient. Salinity and anoxia were highest at the upper and lower edge of the intertidal, respectively. Nutrients and herbivory interacted to control cordgrass biomass, but their relative importance varied with environmental context. Herbivory increased at lower tidal heights to the point that cordgrass transplants onto bare mud substrate were entirely consumed unless crabs were excluded, while nutrients were most important where abiotic stress was reduced. Our results show how the impact of herbivores and nutrients on plant productivity can be dependent on environmental conditions and that the lower intertidal limits of marsh plants can be controlled by herbivory.},
keywords = {abiotic, atlantic, bottom-up, GCE, salt marsh, stress, top-down},
doi = {10.1007/s00442-009-1504-9},
url = {http://www.springerlink.com/content/t2517rh1590t2812/},
author = {Alberti, J. and Casariego, A. M. and Daleo, P. and Fanjul, E. and Silliman, Brian R. and Bertness, Mark D. and Iribarne, O.}
@article {65440,
title = {Alkalinity distribution in the western North Atlantic Ocean margins},
journal = {Journal of Geophysical Research},
volume = {115},
year = {2010},
pages = {15},
abstract = {Total alkalinity (TA) distribution and its relationship with salinity (S) along the western North Atlantic Ocean (wNAO) margins from the Labrador Sea to tropical areas are examined in this study. Based on the observed TA-S patterns, the mixing processes that control alkalinity distribution in these areas can be categorized into a spectrum of patterns that are bracketed by two extreme mixing types, i.e., alongshore current-dominated and river-dominated. Alongshore current-dominated mixing processes exhibit a segmented mixing line with a shared mid-salinity end-member. In such cases (i.e., Labrador Sea, Gulf of Maine, etc.), the y-intercept of the high salinity segment of the mixing line is generally higher than the local river alkalinity values, and it reflects the mixing history of the alongshore current. In contrast, in river-dominated mixing (Amazon River, Caribbean Sea, etc.), good linear relationships between alkalinity and salinity are generally observed, and the zero salinity intercepts of the TA-S regressions roughly match those of the regional river alkalinity values. TA-S mixing lines can be complicated by rapid changes in the river end-member value and by another river nearby with a different TA value (e.g., Mississippi-Atchafalaya/Gulf of Mexico). In the wNAO margins, regression intercepts and river end-members have a clear latitudinal distribution pattern, increasing from a low of \&$\#$8764;300},
keywords = {akalinity, biological removal, coastal ocean mixing, GCE},
doi = {10.1029/2009JC005482},
url = {http://www.agu.org/pubs/crossref/2010/2009JC005482.shtml},
author = {Cai, Wei-Jun. and Hu, Xinping. and Huang, Wei-Jen. and Jiang, Liqing. and Wang, Yongchen. and Peng, Tsung-Hung.}
@article {65448,
title = {Ascomycete fungal communities associated with early decay leaf blades of three Spartina species and a Spartina hybrid in the San Francisco Bay},
journal = {Oecologica.},
volume = {162},
year = {2010},
pages = {435-442},
abstract = {Ascomycetous fungi play an important role in the early stages of decomposition of Spartina alterniflora, but their role in the decomposition of other Spartina species has not been investigated. Here we use fingerprint (T-RFLP) and phylogenetic analyses of the 18S-to-28S internal transcribed spacer (ITS) region to compare the composition of the ascomycete fungal communities on early decay blades of Spartina species (S. alterniflora, S. densiflora, S. foliosa, and a hybrid (S. alterniflora x S. foliosa) collected from three salt marshes in San Francisco Bay and one in Tomales Bay, California, U.S.A. Phaeosphaeria spartinicola was found on all samples collected and was often dominant. Two other ascomycetes, Phaeosphaeria halima and Mycosphaerella sp. strain 2, were also common. These three species are the same ascomycetes previously identified as the dominant fungal decomposers on S. alterniflora on the east coast. Ascomycetes appeared to exhibit varying degrees of host-specificity, demonstrated by grouping patterns on phylogenetic trees. Neither the exotic S. alterniflora nor the hybrid supported fungal flora different from that of the native S. foliosa. However, S. densiflora had a significantly different fungal community than the other species, and hosted at least two unique ascomycetes. Significant differences in the fungal decomposer communities were also detected within species (two clones of S. foliosa), but these were minor and may be due to morphological differences among the plants.},
keywords = {ascomycete, decay, fungi, GCE, microbiology, plant, spartina},
doi = {10.1007/s00442-009-1460-4},
url = {http://www.springerlink.com/content/t7186704g8100t51/},
author = {Lyons, Justine I. and Alber, Merryl. and Hollibaugh, James T.}
@article {65453,
title = {Avian communities of the Altamaha River estuary in Georgia, USA},
journal = {The Wilson Journal of Ornithology},
volume = {122},
year = {2010},
pages = {532},
abstract = {We surveyed male breeding birds in five habitats (bottomland forest, maritime oak [Quercus spp.], pine [Pinus spp.] forest, maritime shrub, saltmarsh) of coastal Georgia, USA using distance-sampling methods to estimate population densities. We examined species-habitat relationships using indicator species analysis (ISA). Acadian Flycatcher (Empidonax virescens) in bottomland forest, Northern Parula (Parula americana) in maritime oak, Brown-headed Nuthatch (Sitta pusilla) in pine forest, Clapper Rail (Rallus longirostris) in saltmarsh, and White-eyed Vireo (Vireo griseus) in shrub habitat ranked highest for Partners in Flight (PIF) priority species by densities. The ISA indicated fewer PIF priority species were associated with saltmarsh, but more species (6) were unique to saltmarsh than any other habitat. Indicator species occurred more often in maritime oak than bottomland forest (8 vs. 6), but both habitats had similar numbers of PIF priority species (4). Shrub habitat covered the smallest area (,0.2\%) and had three PIF priority species, including Painted Bunting (Passerina ciris), the only PIF species with extremely high priority in this study.},
keywords = {birds, GCE, live oak forest, maritime forest, pine forest, salt marsh, species of concern, tidal forest},
doi = {10.1676/09-186.1},
url = {http://findarticles.com/p/articles/mi_hb5046/is_3_122/ai_n55386556/},
author = {Brittain, Ross. and Meretsky, Vicky J. and Craft, Christopher B.}
@article {65469,
title = {Blue crab (Callinectes sapidus Rathbun, 1896) settlement at three Georgia (USA) estuarine sites.},
journal = {Estuaries and Coasts},
volume = {33},
year = {2010},
pages = {688-698},
abstract = {The blue crab, Callinectes sapidus Rathbun, 1896, represents the second most important fishery for coastal Georgia; yet, little is known about environmental forces that affect planktonic postlarval settlement in the region. Here, we describe a study to examine the physical mechanisms responsible for blue crab settlement in the extensive salt marsh system of coastal Georgia. Bottom and surface samplers were placed at three sites along a salinity gradient from a low-salinity site in the Altamaha River to a high-salinity area of the Duplin River, Sapelo Island, GA, USA during 2005. Megalopae and juvenile monitoring occurred from July through December. The majority of both megalopae (86.8\%) and juvenile (89.3\%) blue crabs were recovered in bottom samplers at the low-salinity Altamaha River site during August and early September. Few megalopae were collected at the surface of the Altamaha River or at the two higher-salinity sites in the Duplin and North Rivers. Downwelling winds were unable to explain all settlement events; however, winds with an onshore component regularly preceded settlement events. The use of a multiple-regression model revealed a lagged relationship (r\&$\#$8201;=\&$\#$8201;0.5461, lag = 0},
keywords = {blue crab, callinectes sapidus, GCE, postlarvae},
doi = {10.1007/s12237-009-9259-4},
url = {http://www.springerlink.com/content/w72171p1560t652v/},
author = {Bishop, Thomas. Dale. and Miller, W. R and Walker, R.L. and Hurley, Dorset. and Menken, Theron. and Tilburg, Charles E.}
@article {65480,
title = {Carbon sequestration and nutrient (N, P) accumulation in river-dominated tidal marshes, Georgia, USA},
journal = {Soil Science Society of America Journal},
volume = {74},
year = {2010},
pages = {1027-1038},
abstract = {Soil organic C, N, and P were measured in salt, brackish, and tidal freshwater marshes in river-dominated estuaries (Ogeechee, Altamaha, and Satilla) of the Georgia coast to evaluate the effects of salinity on C, N, and P storageand accumulation. Tidal freshwater marshes had greater concentrations of organic C (10.81\% w/w) and N (0.71\% w/w)than brackish (7.71\% C, 0.50\% N) or salt (5.95\% C, 0.35\% N) marshes. Soil accretion rates of ^137Cs were greaterin tidal freshwater (4.78 mm yr^1) and brackish marshes (4.41 mm yr^1) than in salt marshes (1.91 mm yr^1). Consequently, organic C and N accumulation was greater in tidal freshwater (124 and 8.2 g m^2 yr^1) and brackish (93 and 6.5 g m^2 yr^1) marshes than salt marshes (40 and 2.4 g m^2 yr^1). Phosphorus accumulation was greater in the brackish marshes. Lower salinity tidal freshwater and brackish marshes remove more C, N, and P; however, salt marshes dominate the spatial extent of the study area (60\%) vs. brackish (33\%) and tidal freshwater marshes (7\%). Combinig measurements of C, N, and P accumulation with tidal marsh area, we estimated that tidal freshwater, brackish, and salt marshes stored or removed the equivalent of 2 to 20\% of watershed N inputs entering the estuaries from the terrestrial landscape. After accounting for N2 fixation and denitrification, tidal marshes collectively removed the equivalent of 13 to 32\% of the N entering estuaries. Tidal marshes, especially tidal freshwater and brackish marshes, are important for improving water quality and decreasing the impacts of Neutrophication of estuarine ecosystems.},
keywords = {carbon, GCE, geology, marsh, nitrogen, nutrients, phosphorus, soils},
doi = {10.2136/sssaj2009.0171},
url = {https://www.soils.org/publications/sssaj/abstracts/74/3/1028},
author = {Loomis, Mark. and Craft, Christopher B.}
@article {65481,
title = {Carbonate mineral saturation states along the U.S. east coast},
journal = {Limnology and Oceanography},
volume = {55},
year = {2010},
pages = {2424},
abstract = {To assess the impact of ocean acidification on the carbonate chemistry of the shelf waters off the southeastern United States (South Atlantic Bight [SAB]), we measured carbonate mineral saturation states from January 2005 to May 2006. The findings reveal that aragonite (Varag: 2.6},
keywords = {carbonate mineral saturation states, chemistry, east coast, GCE},
doi = {10.4319/lo.2010.55.6.2424},
url = {http://www.aslo.org/lo/toc/vol_55/issue_6/2424.html},
author = {Jiang, Liqing. and Hartmann, Justin. and Zhang, Longuin. and Cai, Wei-Jun. and Feely, Richard A. and Wang, Yongchen. and Guo, Xianghui. and Gledhill, Dwight K. and Hu, Xinping. and Arzayus, Felipe. and Chen, Feizhou.}
@article {65508,
title = {Comparative Phylogeography of East Coast American Salt Marsh Communities},
journal = {Estuaries and Coasts},
volume = {33},
year = {2010},
pages = {828-839},
abstract = {Identifying differential population structure within metacommunities is key toward describing the mechanisms that maintain biodiversity in natural systems. At both local and regional scales on the North American Atlantic coast, we assessed phylogeographic and genetic diversity patterns of six common salt marsh invertebrates using equivalent sampling schemes and sequence data from the same mitochondrial locus. In general, our results suggest little genetic structure across four previously sampled biogeographic regions and a slight increase in genetic diversity from northern to southern areas; however, two of the species (Geukensia demissa and Uca pugilator) exhibited significant differentiation between the northernmost populations and other regions, consistent with a number of previous studies. Although the minimal genetic structure recovered in this community is consistent with expectations based on the larval life history of the species examined, confirmation of this result suggests that latitudinal shifts in ecological interactions in salt marsh systems are environmentally driven, rather than due to heritable adaptation.},
keywords = {community ecology, GCE, genetics, invertebrates, salt marsh},
doi = {10.1007/s12237-009-9220-6},
author = {Diaz-Ferguson, Edgardo. and Robinson, John D. and Silliman, Brian R. and Wares, John P.}
@article {65532,
title = {The Cycle of Vertical and Horizontal Mixing in a Tidal Creek},
journal = {Journal of Geophysical Research},
volume = {115},
year = {2010},
pages = {C01004},
abstract = {An experimental study of vertical mixing and along-channel dispersion parameterizedin terms of horizontal mixing near the mouth of the Duplin River (a tidal creek borderedby extensive intertidal salt marshes on Sapelo Island, Georgia) was carried out overseveral spring/neap cycles in the fall of 2005. Vertical mixing is modulated on both M4and fortnightly frequencies with maximum turbulent stresses being generated near thebed on periods of maximum flood and ebb and propagating into the water columnshowing a linear dependence with depth. Values are significantly greater on spring tidethan on neap. Horizontal mixing evaluated by salt fluxes is driven and dominated bytidal dispersion, which is also modulated by the fortnightly spring/neap cycle. Net export of salt from the lower Duplin is shown to be due to residual advection modified by upstream tidal pumping. The tidal dispersion coefficient exhibits a pulsating character with greater values on spring tide followed by smaller values on neap tide.},
keywords = {duplin river, GCE, georgia, mixing processes, salt flux, sapelo island, signature publication, tidal mixing},
doi = {10.1029/2008JC005204},
url = {http://www.agu.org/journals/ABS/2010/2008JC005204.shtml},
author = {McKay, Paul. and Di Iorio, Daniela.}
@article {65700,
title = {Is Diet Quality an Overlooked Mechanism for Bergmann{\textquoteright}s Rule?},
journal = {The American Naturalist},
volume = {175},
year = {2010},
pages = {269-276},
abstract = {Bergmann{\textquoteright}s rule (body size increases with latitude) has long interested biologists; however, its mechanism remains unclear. An overlooked mechanism (latitudinal variation in plant quality) might help explain Bergmann{\textquoteright}s rule. We studied three herbivores. In the field, the planthopper Prokelisia and the sea hare Aplysia, but not the long-horned grasshopper Orchelimum, were larger at high latitudes, following Bergmann{\textquoteright}s rule. In the laboratory, all three species grew larger or faster on high-latitude plants. High-latitude diets increased Prokelisia size and Aplysia growth rates by 8\% and 72\%, respectively, enough to explain the increase in field body size toward high latitudes. Therefore, latitudinal variation in herbivore body size could be influenced by latitudinal variation in plant quality, which may directly or indirectly also affect body size in detritivores, parasitoids, and predators. Studies of Bergmann{\textquoteright}s rule should consider the influence of biotic factors on body size in addition to abiotic factors such as temperature and precipitation.},
keywords = {bergmann, biogeography, diet, GCE, latitude, nutrition, physiology, plants, signature publication, size},
doi = {10.1086/649583},
url = {http://www.journals.uchicago.edu/doi/abs/10.1086/649583},
author = {Ho, Chuan-Kai. and Pennings, Steven C. and Carefoot, Thomas H.}
@article {65558,
title = {Distribution and retention of Petrolisthes armatus in a coastal plain estuary: the role of vertical movement in larval transport},
journal = {Estuarine Coastal and Shelf Science},
volume = {88},
year = {2010},
pages = {260-266},
abstract = {Since transport of planktonic larval stages is essential to population maintenance and expansion of many marine species, we examined the spatial and temporal distribution of Petrolisthes armatus (Gibbes, 1850) larvae and the possible underlying physical and behavioral mechanisms responsible for these distributions using a combination of field observations and numerical modeling. The field study consisted of observations of larval abundance and distribution as well as hydrographic surveys of the Satilla River estuary on the east coast of the USA in August 2006. Larvae were found throughout the water column within the tributaries but primarily at depth in the main river. A numerical model was used to examine the effect of flow and possible larval behavior responsible for the observed distribution and the consequences for larval retention in the estuary. Model results that included downward larval movement agreed with the field observations. This agreement provides support for the hypothesis that P. armatus larvae vertically migrate within the water column, which aids in their retention within the estuary.},
keywords = {crabs, estuary, GCE, larvae, larval-transport, models, petrolisthes armatus (green porcelain crab), vertical movement, zoeae},
doi = {10.1016/j.ecss.2010.04.004},
url = {http://dx.doi.org/10.1016/j.ecss.2010.04.004},
author = {Tilburg, Charles E. and Seay, Jennie E. and Bishop, Thomas. Dale. and Miller, W. R and Meile, Christof.}
@article {65579,
title = {Ecosystem development on a coastal barrier island dune chronosequence},
journal = {Journal of Coastal Research},
volume = {26},
year = {2010},
pages = {726-732},
abstract = {Soil and litter organic carbon, nitrogen, and phosphorus were measured across a dune chronosequence on Sapelo Island, Georgia, U.S.A., to characterize ecosystem development and nutrient cycling during primary succession. As successional theory predicts, litter biomass and soil organic matter increased with dune age. The proportion of nutrients contained in the litter also increased with dune age. No litter was present in the grass-dominated foredunes, whereas in the forested dunes litter accounted for 37\%, 17\%, and 0.11\% of the ecosystem (soil plus litter) C, N, and P, respectively. Soil C and N pools increased from the foredunes to older dune classes. Surface soil (0},
keywords = {carbon, dune, ecosystem, GCE, geology, island, morella cerifera, nitrogen, phosphorus., succession},
doi = {10.2112/08-1167},
url = {http://www.bioone.org/doi/abs/10.2112/08-1167.1},
author = {Tackett, Nick. and Craft, Christopher B.}
@article {65580,
title = {Ecosystem functions of tidal fresh, brackish and salt marshes on the Georgia coast},
journal = {Estuaries and Coasts},
volume = {33},
year = {2010},
pages = {161-169},
abstract = {We examined patterns of habitat function (plant species richness), productivity (plant aboveground biomass and total C), and nutrient stocks (N and P in aboveground plant biomass and soil) in tidal marshes of the Satilla, Altamaha, and Ogeechee Estuaries in Georgia, USA. We worked at two sites within each salinity zone (fresh, brackish, and saline) in each estuary, sampling a transect from the creekbank to the marsh platform. In total, 110 plant species were found. Site-scale and plot-scale species richness decreased from fresh to saline sites. Standing crop biomass and total carbon stocks were greatest at brackish sites, followed by freshwater then saline sites. Nitrogen stocks in plants and soil decreased across sites as salinity increased, while phosphorus stocks did not differ between fresh and brackish sites but were lowest at salty sites. These results generally support past speculation about ecosystem change across the estuarine gradient, emphasizing that ecosystem function in tidal wetlands changes sharply across the relatively short horizontal distance of the estuary. Changes in plant distribution patterns driven by global changes such as sea level rise, changing climates, or fresh water withdrawal are likely to have strong impacts on a variety of wetland functions and services.},
keywords = {aboveground biomass, GCE, macrophytes, nitrogen, nutrients, phosphorus, species richness, vegetation},
doi = {10.1007/s12237-009-9230-4},
url = {http://www.springerlink.com/content/1207kq6120636357/},
author = {Wieski, Kazimierz. and Guo, Hongyu. and Craft, Christopher B. and Pennings, Steven C.}
@article {65582,
title = {Ecosystem services as a common language for coastal ecosystem-based management},
journal = {Conservation Biology},
volume = {24},
year = {2010},
pages = {207-216},
abstract = {Ecosystem-based management is logistically and politically challenging because ecosystems are inherently complex and management decisions affect a multitude of groups. Coastal ecosystems, which lie at the interface between marine and terrestrial ecosystems and provide an array of ecosystem services to different groups, aptly illustrate these challenges. Successful ecosystem-based management of coastal ecosystems requires incorporating scientific information and the knowledge and views of interested parties into the decision-making process. Estimating the provision of ecosystem services under alternative management schemes offers a systematic way to incorporate biogeophysical and socioeconomic information and the views of individuals and groups in the policy and management process. Employing ecosystem services as a common language to improve the process of ecosystem-based management presents both benefits and difficulties. Benefits include a transparent method for assessing trade-offs associated with management alternatives, a common set of facts and common currency on which to base negotiations, and improved communication among groups with competing interests or differing worldviews. Yet challenges to this approach remain, including predicting how human interventions will affect ecosystems, how such changes will affect the provision of ecosystem services, and how changes in service provision will affect the welfare of different groups in society. In a case study from Puget Sound, Washington, we illustrate the potential of applying ecosystem services as a common language for ecosystem-based management.},
keywords = {ecosystem services, ecosystem-based management, GCE, management},
doi = {10.1111/j.1523-1739.2009.01355.x},
url = {http://onlinelibrary.wiley.com/doi/10.1111/j.1523-1739.2009.01355.x/abstract},
author = {Granek, Elise F. and Barbier, Edward B. and Aswani, S. and Ruckelshaus, M. and Perillo, M. E. and Silliman, Brian R. and Muthiga, Nyawira. and Bael, D. and Wolanski, Eric. and Polasky, Stephen. and Kappel, Carrie V. and Reed, D.J. and Stoms, D.M. and Koch, Evamaria W. and Kennedy, Christopher J. and Cramer, Abby. and Hacker, Sally D.}
@article {65591,
title = {Effects of Five Years of Nitrogen and Phosphorus Additions on a Zizaniopsis miliacea Tidal Freshwater Marsh, Georgia (USA).},
journal = {Aquatic Botany},
volume = {95},
year = {2010},
pages = {17-23},
abstract = {The purpose of this experiment was to determine if nitrogen (N) or phosphorus (P) acts as the limiting nutrient for tidal freshwater marsh vegetation. To answer this question, we added N, P, and N+ P to a tidal freshwater marsh dominated by Zizaniopsis miliacea (Michx.) (giant cutgrass) in Georgia, USA, for five years to determine their effects on aboveground and belowground biomass and nutrient (N, P) uptake. Nitrogen and P were applied twice per year at an annual rate of 50 gm-2 year-1 and 10gm-2 year-1, respectively. Aboveground biomass and leaf C, N, and P were sampled in August of each year. Belowground biomass and C, N, and P content were measured in August of year five. After two years, plots receiving N and N+ P had significantly greater aboveground biomass than the control and P plots. This trend continued through the fifth year of the study and resulted in two to three times more aboveground biomass at the end of the fifth year in the N (1570 gm-2) and N+ P (1264 gm-2) plots relative to P (710 gm-2) and control (570 gm-2) plots. After five years of nutrient additions, macro-organic matter (MOM), the living plus dead root and rhizome mat (0},
keywords = {cutgrass, eutrophication, GCE, nitrogen, nutrients, phosphorus, tidal fresh marsh},
doi = {10.1016/j.aquabot.2011.03.003},
author = {Ket, Wes. and Schubauer-berigan, Joe. and Craft, Christopher B.}
@article {65593,
title = {Effects of Increased Salinity and Inundation on Inorganic N and P Sorption by Tidal Freshwater Floodplain Forest Soils, Georgia (USA).},
journal = {Estuaries and Coasts},
year = {2010},
keywords = {desorption, GCE, nitrogen, nutrients, phosphorus, salt water intrusion, sorption, tidal forests},
author = {Jun, Mi. hee. and Craft, Christopher B.}
@article {65599,
title = {Effects of upwelling on short term variability in microbial processes in estuarine sediments},
journal = {Aquatic Microbial Ecology},
volume = {58},
year = {2010},
pages = {261-271},
abstract = {We examined short-term variability in sediment microbial processes and biogeochemistry in response to decreased irradiance accompanying an upwelling event. Potential nitrification, extractable nutrients, solid phase iron and pore water sulfide concentrations were measured several times at 3 locations in Elkhorn Slough, California, USA. Benthic fluxes of nitrate+nitrite, ammonium, phosphate, sediment oxygen consumption and denitrification from N2/Ar flux were also measured. Fog that was associated with upwelling in Monterey Bay reduced photosynthetically active radiation in Elkhorn Slough, which led to increased duration of water column hypoxia. Solid phase Fe3+ concentrations and potential nitrification rates declined while pore water sulfide increased over this period. While potential nitrification rates from this study are lower than rates from estuaries that do not experience hypoxia or anoxia, nitrifiers in Elkhorn Slough appear to be capable of adjusting to changing environmental conditions, specifically of tolerating low levels of sulfide. The nitrifying assemblage was similar to the community of ammonia-oxidizing bacteria and ammonia-oxidizing archaea that was previously reported from this system. Eutrophic shallow estuaries like Elkhorn Slough are delicately poised such that their sediment biogeochemistry responds quickly to relatively small changes in the light environment.},
keywords = {ammonia, ammonia oxidation, aoa, aob, crenarchaea, elk horn slough, GCE, hypoxia, irradiance, nitrification, upwelling},
doi = {10.3354/ame01387},
url = {http://www.int-res.com/articles/ame_oa/a058p261.pdf},
author = {Caffrey, Jane M. and Hollibaugh, James T. and Bano, Nasreen. and Haskins, John.}
@article {81017,
title = {Effects of upwelling on short term variability in microbial processes in estuarine sediments},
volume = {58},
year = {2010},
pages = {261-271},
abstract = {We examined short-term variability in sediment microbial processes and biogeochemistry in response to decreased irradiance accompanying an upwelling event. Potential nitrification, extractable nutrients, solid phase iron and pore water sulfide concentrations were measured several times at 3 locations in Elkhorn Slough, California, USA. Benthic fluxes of nitrate+nitrite, ammonium, phosphate, sediment oxygen consumption and denitrification from N2/Ar flux were also measured. Fog that was associated with upwelling in Monterey Bay reduced photosynthetically active radiation in Elkhorn Slough, which led to increased duration of water column hypoxia. Solid phase Fe3+ concentrations and potential nitrification rates declined while pore water sulfide increased over this period. While potential nitrification rates from this study are lower than rates from estuaries that do not experience hypoxia or anoxia, nitrifiers in Elkhorn Slough appear to be capable of adjusting to changing environmental conditions, specifically of tolerating low levels of sulfide. The nitrifying assemblage was similar to the community of ammonia-oxidizing bacteria and ammonia-oxidizing archaea that was previously reported from this system. Eutrophic shallow estuaries like Elkhorn Slough are delicately poised such that their sediment biogeochemistry responds quickly to relatively small changes in the light environment.},
keywords = {Ammonia-oxidizing bacteria, benthic flux, estuaries, GCE, microbes, microbial ecology, nitrification, nitrogen, sediments, upwelling},
doi = {10.3354/ame01387},
url = {http://www.int-res.com/abstracts/ame/v58/n3/p261-271/},
author = {Caffrey, Jane M. and Hollibaugh, James T. and Bano, Nasreen and Haskins, John}
@article {65604,
title = {Environmental Factors Shaping Microbial Community Structure in Salt Marsh Sediments.},
journal = {Marine Ecology Progress Series},
volume = {399},
year = {2010},
pages = {15-26},
abstract = {We examined benthic microbial communities in three contrasting subtidal salt marsh sediments over the course of a year to investigate the relationship between environmental conditions and benthic microbial community structure. Samples were collected monthly from a high energy, sandy beach, a tidal creek bed, and a Spartina alterniflora marsh border. The concentrations and biomasses of benthic microalgae (BMA), total and potentially active bacteria (measured by an enzyme-activated fluorogenic compound), heterotrophic protists, and metazoan meiofauna were measured at each location. Sediment grain size and porewater pH explained most of the variability in biomass distributions; variations in benthic biomass did not correlate well with temperature. There was a seasonal shift from a BMA-dominated community in the spring and summer months to bacteria-dominated communities in the autumn at all locations, when inactive bacteria were most abundant. When normalized to sediment porewater volume, benthic protists concentrations were not significantly related to sediment porosity. Benthic protist porewater concentrations (mean: 3.4x103, range: 0.1},
keywords = {bacteria, biomass, GCE, marine sediments, microzoobenthos, protists, salt marsh},
doi = {10.3354/meps08385},
url = {http://www.int-res.com/abstracts/meps/v399/p15-26/},
author = {First, Matthew R. and Hollibaugh, James T.}
@article {65622,
title = {Facilitation cascade explains positive relationship between native biodiversity and invasion success},
journal = {Ecology},
volume = {91},
year = {2010},
pages = {1269-1275},
abstract = {The pervasive impact of invasive species has motivated considerable research to understand how characteristics of invaded communities, such as native species diversity, affect the establishment of invasive species. Efforts to identify general mechanisms that limit invasion success, however, have been frustrated by disagreement between landscape-scale observations that generally find a positive relationship between native diversity and invasibility and smaller-scale experiments that consistently reveal competitive interactions that generate the opposite relationship. Here we experimentally elucidate the mechanism explaining the large-scale positive associations between invasion success and native intertidal diversity revealed in our landscape-scale surveys of New England shorelines. Experimental manipulations revealed this large-scale pattern is driven by a facilitation cascade where ecosystem-engineering species interact nonlinearly to enhance native diversity and invasion success by alleviating thermal stress and substrate instability. Our findings reveal that large-scale diversity},
keywords = {biodiversity, ecosystem engineer, facilitation cascade, foundation species, GCE, invasion paradox, invasive species, marine conservation, nonlinear ecological interactions},
doi = {10.1890/09-1301.1},
url = {http://www.esajournals.org/doi/abs/10.1890/09-1301.1},
author = {Altieri, Andrew H. and van Wesenbeeck, Bregje K. and Bertness, Mark D. and Silliman, Brian R.}
@article {65639,
title = {Flow cytometric measurement of ingestion and digestion of bacteria by ciliates and recovery of a digestion-resistant Campylobacter jejuni},
journal = {Applied and Environmental Microbiology},
year = {2010},
keywords = {cryptic survival, GCE, legionella, protist, trojan horse},
author = {First, Matthew R. and Park, N. Y. and Berrang, M. E. and Meinersmann, R. J. and Bernhard, J. M. and Gast, R. J. and Hollibaugh, James T.}
@article {65652,
title = {Habitat cascades: the conceptual context and global relevance of facilitation cascades via habitat formation and modification.},
journal = {Integrative and Comparative Biology},
volume = {50},
year = {2010},
pages = {158-175},
abstract = {The importance of positive interactions is increasingly acknowledged in contemporary ecology. Most research has focused on direct positive effects of one species on another. However, there is recent evidence that indirect positive effects in the form of facilitation cascades can also structure species abundances and biodiversity. Here we conceptualize a specific type of facilitation cascade},
keywords = {cascades, GCE, habitat, VCR},
doi = {10.1093/icb/icq042},
url = {http://icb.oxfordjournals.org/content/50/2/158.short},
author = {Thomsen, Mads S. and Wernberg, T and Alteiri, A. and Tuya, F. and Gulbransen, D. and McGlathery, Karen J. and Holmer, M. and Silliman, Brian R.}
@article {65701,
title = {Island Archaeology and the Native American Economies (2500 B.C.},
journal = {Journal of Field Archaeology},
volume = {35},
year = {2010},
pages = {283-297},
abstract = {Our research along the Georgia coast of the southeastern United States explores the role that small islands played in Native American economies over some 4000 years (ca. 2500 B.C.},
keywords = {coastal archaeology, GCE, island archaeology, Native American, settlement patterns, signature publication, Southeastern United States},
doi = {10.1179/009346910X12707321358991},
url = {http://www.ingentaconnect.com/content/maney/jfa/2010/00000035/00000003/art00002},
author = {Thompson, Victor D. and Turck, John A.}
@article {65756,
title = {Multiscale Diversity in the Marshes of the Georgia Coastal Ecosystems LTER},
journal = {Estuaries and Coasts},
volume = {33},
year = {2010},
pages = {865-877},
abstract = {Factors that maintain genetic and species diversity may act in concert in natural ecosystems. Here, we investigate correlations between genetic diversity (in eight salt marsh species) and community species diversity. A significant positive correlation existed between genetic diversity and species richness, although the relationship was not significant for any species individually. Nonetheless, four of the eight comparisons showed strong positive relationships between genetic and species diversity. Additionally, several abiotic variables were used in a model selection procedure to determine what site-level characteristics might drive differences in genetic diversity in this system. The rate of larval influx, as measured by barnacle abundance on Spartina alterniflora, was the strongest predictor of site-level genetic diversity in our samples. Our results suggest that estuarine management efforts should consider recruitment rates when selecting areas for protection.},
keywords = {diversity, GCE, genetics, invertebrates, marsh, plants, settlement, signature publication},
doi = {10.1007/s12237-009-9188-2},
url = {http://www.springerlink.com/content/a261g14m0016q708/},
author = {Robinson, John D. and Diaz-Ferguson, Edgardo. and Poelchau, Monica. and Pennings, Steven C. and Bishop, Thomas. Dale. and Wares, John P.}
@article {65771,
title = {Nutrient enrichment enhances hidden differences in phenotype to drive a cryptic plant invasion},
journal = {Oikos},
volume = {119},
year = {2010},
pages = {1776-1784},
abstract = {Many mechanisms of invasive species success have been elucidated, but those driving cryptic invasions of non-native genotypes remain least understood. In one of the most successful cryptic plant invasions in North America, we investigate the mechanisms underlying the displacement of native Phragmites australis by its Eurasian counterpart. Since invasive Phragmites},
keywords = {GCE, invasion, nutrient, phenotype, plant},
doi = {10.1111/j.1600-0706.2010.18647.x},
url = {http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0706.2010.18647.x/abstract},
author = {Holdredge, Christine. and Bertness, Mark D. and Wettberg, E. V. and Silliman, Brian R.}
@article {65786,
title = {Pelagic community respiration on the continental shelf off Georgia, USA},
journal = {Biogeochemistry},
volume = {98},
year = {2010},
pages = {101},
abstract = {The South Atlantic Bight (SAB) has been a focus for the study of continental shelf ecosystem respiration during the past two decades. However, two questions concerning respiration in this area have yet to be answered. First, why do previous estimates of respiration in the SAB exceed measured carbon fixation rates by almost an order of magnitude? Second, considering that bacteria are responsible for most of the pelagic community respiration in the SAB, why is respiration almost uniform from the coastline to the shelf break, while bacterial production estimates decrease offshore? This study addresses these critical questions by presenting new pelagic community respiration data that were collected across the entire width of the continental shelf off Georgia, USA from June 2003 to May 2006. The respiration was calculated as in vitro changes of dissolved oxygen and dissolved inorganic carbon concentrations during deck incubations. The measured respiration rates ranged from 0.3(},
keywords = {CO2, GCE, metabolism, oceanography, respiration},
doi = {10.1007/s10533-009-9379-8},
url = {http://www.springerlink.com/content/n6684pw510j4627p/},
author = {Jiang, Liqing. and Cai, Wei-Jun. and Wang, Yongchen. and Diaz, J. and Yager, Patricia. and Hu, Xinping.}
@article {81066,
title = {Plasticity, not adaptation to salt level, explains variation along a salinity gradient in a salt marsh perennial},
volume = {33},
year = {2010},
pages = {840-852},
abstract = {Evolutionary ecologists have long been intrigued by the fact that many plant species can inhabit a broad range of environmental conditions, and that plants often exhibit dramatic differences in phenotype across environmental gradients. We investigated responses to salinity treatments in the salt marsh plant Borrichia frutescens to determine if the species is responding to variation in edaphic salt content through phenotypic plasticity or specialized trait response. We grew seedlings from fruits collected in high and low salt microhabitats, assigned seedlings to high and low salt treatments in a greenhouse and measured traits related to salt tolerance. All traits were highly plastic in response to salinity. Plants from the two microhabitats did not differ in trait means or respond differently to the treatments. These results suggest that environmental differences between the two microhabitats are not creating genotypes adapted to high and low salt levels. In addition, despite evidence for variation in allozyme markers in this population, there was no significant genotypic variation (family effect) in any of the trait means measured across microhabitats. There was variation in plasticity for only leaf Na and leaf B concentration. The high degree of plasticity for all traits and the lack of differences among microhabitats across the salinity gradient suggest plasticity may be fixed for this species.},
keywords = {borrichia frutescens, GCE, genetic specialization, local adaptation, phenotypic plasticity, salinity gradient, salt marsh plant, salt tolerance traits, sea ox-eye daisy},
doi = {10.1007/s12237-009-9186-4},
author = {Richards, Christina L. and White, Susan N. and McGuire, Mary Anne and Franks, Steven J. and Donovan, Lisa A. and Mauricio, Rodney}
@inbook {65832,
title = {The Rhythms of Space-Time and the Making of Monuments and Places during the Archaic},
booktitle = {Trend, Tradition, and Turmoil: What Happened to the Southeastern Archaic?},
year = {2010},
pages = {217-227},
publisher = {Anthropological Papers Number 93 of the American Museum of Natural History, New York},
organization = {Anthropological Papers Number 93 of the American Museum of Natural History, New York},
keywords = {GCE, isotope, sea level rise, settlement, shell ring},
author = {Thompson, Victor D.},
editor = {Sanger, Matt}
@mastersthesis {65887,
title = {Synoptic comparison of salt marsh spatial structure using hyperspectral imagery at NOAA National Estuarine Research Reserves},
year = {2010},
pages = {177},
school = {Creighton University},
address = {Omaha, NE},
abstract = {As a dynamic system, salt marshes are highly productive habitats. Exceedingly dependent on specific tolerances to tidal regimes, temperature, elevation, and salinity, the plant composition and structure of a salt marsh are highly variable. Due in part to their visible spatial patterns and the impracticality of large scale field observations, aerial and satellite remote sensing has provided an effective alternative for studying these plant communities. This research focused on the use of hyperspectral remote sensing to advance an overall understanding of salt marsh ecosystem productivity, diversity, and abundance within specific National Estuarine Research Reserves (NERRs) using AISA (Airborne Imaging Spectrometer for Different Applications) imagery.The overall goal of my thesis was to create a synoptic overview and site comparisons of salt marsh vegetation for seven NERRs, within their respective growing seasons, using three remote sensing vegetation indices. Additionally, within and between site geospatial patterns were examined using two landscape metrics. The seven sites were located in a range of climates, tidal, and river discharge regimes between Texas and Delaware.Across all sites, the NDVI and MSAVI indices were well suited for distinguishing structural differences and illustrating variations in relative biomass and plant vigor at each site. They both showed latitudinal and longitudinal shifts in histogram distributions, relatable to nutrient, tidal, and climate regimes. These indices were also useful for discriminating features unique to individual sites, such as exposed, intertidal mud flats (Georgia site) and robust Phramites australis stands (Delaware site).The VARIgreen index, more closely captured the photosynthetic capacity and "greenness" of salt marsh vegetation, and was more sensitive to phenological changes and foliage pigment densities. This index was more responsive to spring greening and late summer senescence. As a result, VARIgreen{\textquoteright}s distributional patterns appeared more sensitive to growing season patterns.Patches per unit area (PPU) was an effective landscape metric for measuring patchiness of vegetation index classes for the entire landscape. The Texas, Georgia, and South Carolina sites displayed the highest PPU values, while sites in Mississippi and West Florida had the lowest values. Although PPU illustrated the abundance of different patches in a single area, it was biased towards dominant classes. In comparison, the Shannon Diversity Index (SDI) captured the degree of equitability of all classes of patches. The largest class diversity and SDI values were found in the Delaware and West Florida sites.Ultimately, the vegetation indices and landscape metrics helped to show spatial variations at each site. As a result, site characterizations, unique to each site helped to explain the structure and productivity of the eight datasets.},
keywords = {community structure, GCE, landscape metrics, remote sensing, salt marshes, vegetation indices},
url = {http://hdl.handle.net/10504/16048},
author = {Seminara, Drew N.}
@article {65901,
title = {Transport and retention of a conservative tracer in an isolated creek},
journal = {Estuarine, Coastal and Shelf Science},
volume = {87},
year = {2010},
pages = {333-345},
abstract = {A study of tracer transport and retention in a small tidal creek and marsh system located in the southeastern US was conducted using a three-dimensional hydrodynamic model and data from a dye tracer release. The model simulated tidally driven flow, including inundation and drying out of the marshes and the dispersal of the dye tracer. Flow measurements in the tidal creek showed that the simulations appeared to generally duplicate the tidally driven flow into and out of the tidal creeks and marshes. The dye tracer experiment was conducted to test the hydrodynamic model},
keywords = {conservative tracers, flushing time, GCE, intertidal area, numerical simulation, sensitivity analysis, tidal creek},
doi = {10.1016/j.ecss.2010.01.010},
url = {http://dx.doi.org/10.1016/j.ecss.2010.01.010},
author = {Blanton, Jackson O. and Garrett, A. and Bollinger, J. and Hayes, D. and Koffman, L. and Amft, Julie. and Moore, Trent C.}
@article {65944,
title = {Adaptive Cycles of Coastal Hunter-Gatherers},
journal = {American Antiquity},
volume = {74},
year = {2009},
pages = {255-278},
abstract = {Along the southeastern Atlantic coast of Georgia, hunter-gatherer groups substantially altered the landscape for more than three millennia (ca. 4,200\&$\#$8213;1,000 B.P.) leaving behind a distinct material record in the form of shell rings, middens, and burial mounds. During this time, these groups experienced major changes in sea level and resource distribution. Specifically, we take a resilience theory approach to address these changes and discuss the utility of this theory for archaeology in general. We suggest that despite major destabilizing forces in the form of sea-level lowering and its concomitant effects on resource distribution, cultural systems rebounded to a structural pattern similar to the one expressed prior to environmental disruption. We propose, in part, the ability for people to return to similar patterns was the result of the high visibility of previous behaviors inscribed on the landscape in the form of shell middens and rings from the period preceding environmental disruption. Finally, despite a return to similar cultural formulations, hunter-gatherers experienced some fundamental changes resulting in modifications to existing behaviors (e.g., ringed villages) as well as the addition of new ones in the form of burial-mound construction.},
keywords = {archaeology, athropology, gatherer, GCE, human dimensions, hunter},
author = {Thompson, Victor D. and Turck, John A.}
@inbook {65957,
title = {Anthropogenic threats to Australasian coastal salt marshes},
booktitle = {Human Impacts on Salt Marshes: A Global Perspective},
year = {2009},
pages = {361-390},
publisher = {University of California Press},
organization = {University of California Press},
keywords = {anthropogenic, disturbance, ecology, GCE, human dimensions, salt marsh},
author = {Thomsen, Mads S. and Adams, P. and Silliman, Brian R.},
editor = {Bertness, Mark D.}
@article {65982,
title = {Benthic metabolism and the fate of dissolved inorganic nitrogen in intertidal sediments},
journal = {Estuarine Coastal and Shelf Science},
volume = {83},
year = {2009},
pages = {392-402},
abstract = {We determined patterns of benthic metabolism and examined the relative importance of denitrification (DNF) and dissimilatory nitrate reduction to ammonium (DNRA) as sinks for nitrate (NO3\&$\#$8722;) in intertidal sediments in the presence and absence of benthic microalgal (BMA) activity. By influencing the activity of BMA, light regulated the metabolic status of the sediments, and, in turn, exerted strong control on sediment nitrogen dynamics and the fate of inorganic nitrogen. A pulsed addition of 15N-labeled NO3\&$\#$8722; tracked the effect and fate of dissolved inorganic nitrogen (DIN) in the system. Under illuminated conditions, BMA communities influenced benthic fluxes directly, via DIN uptake, and indirectly, by altering the oxygen penetration depth. Under dark hypoxic and anoxic conditions, the fate of water column NO3\&$\#$8722; was determined largely by three competing dissimilatory reductive processes; DNF, DNRA, and, on one occasion, anaerobic ammonium oxidation (anammox). Mass balance of the added 15N tracer illustrated that DNF accounted for a maximum of 48.2\% of the 15NO3\&$\#$8722; reduced while DNRA (a minimum of 11.4\%) and anammox (a minimum of 2.2\%) accounted for much less. A slurry experiment was employed to further examine the partitioning between DNF and DNRA. High sulfide concentrations negatively impacted rates of both processes, while high DOC:NO3\&$\#$8722; ratios favored DNRA over DNF.},
keywords = {benthic metabolism, GCE, intertidal, nitrate sinks, sediments},
doi = {10.1016/j.ecss.2009.04.012},
url = {http://dx.doi.org/10.1016/j.ecss.2009.04.012},
author = {Porubsky, William P. and Weston, Nathaniel B. and Joye, Samantha B.}
@inbook {65987,
title = {Biogeochemical dynamics of coastal tidal flats},
booktitle = {Coastal Wetlands: An Integrated Ecosystem Approach},
year = {2009},
pages = {345-374},
publisher = {Elsevier},
organization = {Elsevier},
address = {Amsterdam, The Netherlands},
keywords = {biogeochemistry, GCE, nutrients, tidal flats},
url = {http://www.elsevier.com/wps/find/bookdescription.cws_home/716674/description},
author = {Joye, Samantha B. and Cook, P. and de Beer, D.},
editor = {Brinson, Mark}
@article {65998,
title = {Can conservation biologists rely on established community structure rules to manage novel systems? . . . Not in salt marshes},
journal = {Ecological Applications},
volume = {19},
year = {2009},
pages = {413},
abstract = {We experimentally examined plant zonation in a previously unstudied Chilean salt marsh system to test the generality of mechanisms generating zonation of plants across intertidal stress gradients. Vertical zonation in this system is striking. The low-lying clonal succulent, Sarcocornia fruticosa, dominates the daily flooded low marsh, while intermediate elevations are dominated by the much taller Spartina densiflora. Irregularly flooded higher elevations are dominated by Schoenoplectus californicus, with the small forb, Selliera radicans, found associated with Schoenoplectus at its base. Transplant studies of all four species into each zone both with and without competition revealed the mechanisms driving these striking patterns in plant segregation. In the regularly flooded low marsh, Sarcocornia and Spartina grow in the zone that they normally dominate and are displaced when reciprocally transplanted between zones with neighbors, but without neighbors they grow well in each other},
keywords = {community, conservation, ecology, GCE, management, salt marsh},
doi = {10.1890/07-1000.1},
url = {http://www.esajournals.org/doi/full/10.1890/07-1000.1},
author = {Farina, J.E. and Silliman, Brian R. and Bertness, Mark D.}
@mastersthesis {66002,
title = {Carbon Dioxide in Estuaries and Continental Shelves of Southeastern United States -- Air-Water Fluxes and the Underlying Biogeochemical Cycling},
year = {2009},
pages = {161},
school = {University of Georgia},
address = {Athens},
abstract = {The dissertation strives to understand the air-water fluxes of carbon dioxide (CO2) and their biogeochemical mechanisms in estuaries and continental shelves of Southeastern United States.It consists of two parts: CO2 in estuaries and CO2 on continental shelves.Part I: air-water CO2 fluxes in river- and marine-dominated estuaries. The first part of the dissertation is covered in Chapter 2. It is about a comparative study of air-water CO2 fluxes and their different biogeochemical mechanisms in river- and marine dominated estuaries. Recent studies have shown that CO2 degassing by estuaries (0.4 Pg C yr-1)could almost counterbalance 30\% of the CO2 sink by the open ocean (1.2-1.6 Pg C yr-1),suggesting the important role of estuaries in global air-water CO2 exchange. However, most estuarine CO2 studies have focused on river-dominated estuaries, while little attention has been given to marine-dominated estuaries; even though marine-dominated estuaries account for about half of the total surface area of global estuaries. In this study, surface water pCO2 was studied in these two types of estuaries in Georgia, USA from December 2002 to May 2004. This study showed that air-water CO2 fluxes in river-dominated estuaries were 2-3 times those in marine dominated estuaries. Findings show that DIC inputs from the river were responsible for the extraCO2 degassing in the river-dominated estuaries. Due to the large flux differences between these two types of estuaries, the current global estimates of air-water CO2 fluxes in estuaries (which are almost exclusively based on river-dominated estuaries) could have been overestimated.Part II: air-water CO2 fluxes on continental shelf of southeastern United States. This part of the dissertation is covered in Chapter 3, 4, and 5. Previous studies argued that contrary to the usual},
keywords = {air-sea exchange, carbon dioxide, GCE, spatial and seasonal variability},
author = {Jiang, Liqing.}
@article {66007,
title = {Centuries of human-driven change in salt marsh ecosystems},
journal = {Annual Review of Marine Science},
volume = {1},
year = {2009},
pages = {117-141},
abstract = {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 ecosystems},
keywords = {change, ecology, ecosystems, GCE, human impacts, salt marsh},
doi = {10.1146/annurev.marine.010908.163930},
url = {http://arjournals.annualreviews.org/doi/abs/10.1146/annurev.marine.010908.163930},
author = {Bromberg-Gedan, Keryn. and Silliman, Brian R. and Bertness, Mark D.}
@article {66042,
title = {A comparision between above-water surface and subsurface spectral reflectances collected over inland waters.},
journal = {GeoCarto International},
volume = {24},
year = {2009},
pages = {133-141},
abstract = {The objective of the research was to undertake a quantitative comparison of spectral reflectance measurements made slightly above the surface of water bodies with themeasurements made slightly below the surface. The study is focused on three rivers; two in Georgia, USA and one in Japan. As expected, the differences in reflectance are not constant and vary with the wavelength. The contribution of surface-reflection effects to the surface reflectance measured slightly above the water is both pronounced and highlyvariable, but while they do alter the magnitude of the upwelling signal, they do notchange the general shape of the spectral profiles. The correction of surface-reflectioneffects by assuming a proportionality factor (\&$\#$961;) is not considered to be efficient forinland fresh water bodies. For in-situ spectroscopy, the recommended approach is tomeasure upwelling radiance slightly below the water},
keywords = {altamaha river, GCE, monobe river, spectroscopy, st. marys river, water optics},
doi = {10.1080/10106040802460707},
author = {Bhatti, A.M. and Rundquist, D.C. and Schalles, John F. and Ramirez, L. and Nasu, S.}
@article {81136,
title = {Distribution and ecological role of the non-native macroalga Gracilaria vermiculophylla in Virginia salt marshes},
volume = {11},
year = {2009},
pages = {2303-2316},
abstract = {Intertidal salt marshes are considered harsh habitats where relatively few stress-resistant species survive. Most studies on non-native species in marshes describe terrestrial angiosperms. We document that a non-native marine macroalga, Gracilaria vermiculophylla, is abundant throughout Virginia},
keywords = {distribution, GCE, gracilaria vermiculophylla, invasive species, macroalgae, salt marsh},
doi = {10.1007/s10530-008-9417-9},
url = {http://www.springerlink.com/content/e5k373n266877734/},
author = {Thomsen, Mads S. and McGlathery, Karen J. and Schwarzschild, A. and Silliman, Brian R.}
@article {66097,
title = {Distribution and ecological role of the non-native macroalga Gracilaria vermiculophylla in Virginia salt marshes},
journal = {Biological Invasions},
volume = {11},
year = {2009},
pages = {2303-2316},
keywords = {GCE, VCR},
doi = {10.1007/s10530-008-9417-9},
url = {DOI 10.1007/s10530-008-9417-9},
author = {Thomsen, Mads S. and McGlathery, K. J. and Schwartzchild, A. and Silliman, Brian R.}
@article {66101,
title = {The diverse bacterial community in intertidal, anaerobic sediments at Sapelo Island, Georgia},
journal = {Microbial Ecology},
volume = {58},
year = {2009},
pages = {244-261},
abstract = {The phylogenetic diversity and composition of the bacterial community in anaerobic sediments from Sapelo Island, GA, USA were examined using 16S rRNA gene libraries. The diversity of this community was comparable to that of soil, and 1,186 clones formed 817 OTUs at 99\% sequence similarity. Chao1 estimators for the total richness were also high, at 3,290 OTUs at 99\% sequence similarity. The program RDPquery was developed to assign clones to taxonomic groups based upon comparisons to the RDP database. While most clones could be assigned to describe phyla, fewer than 30\% of the clones could be assigned to a described order. Similarly, nearly 25\% of the clones were only distantly related (<90\% sequence similarity) to other environmental clones, illustrating the unique composition of this community. One quarter of the clones were related to one or more undescribed orders within the \&$\#$947;-Proteobacteria. Other abundant groups included the \&$\#$948;-Proteobacteria, Bacteroidetes, and Cyanobacteria. While these phyla were abundant in other estuarine sediments, the specific members at Sapelo Island appeared to be different from those previously described in other locations, suggesting that great diversity exists between as well as within estuarine intertidal sediments. In spite of the large differences in pore water chemistry with season and depth, differences in the bacterial community were modest over the temporal and spatial scales examined and generally restricted to only certain taxa.},
keywords = {16s, bacteria, community, GCE, intertidal, microbiology, sediment},
doi = {10.1007/s00248-008-9481-9},
url = {http://www.springerlink.com/content/6743370258u06313/},
author = {Lasher, Chris. and Dyszynski, Glen. and Everett, Karen. and Ye, Wendy. and Sheldon, Wade M. and Joye, Samantha B. and Moran, Mary Ann. and Whitman, William B.}
@article {66105,
title = {Drought-associated shifts in Spartina alterniflora and S. cynosuroides in the Altamaha River estuary},
journal = {Wetlands},
volume = {29},
year = {2009},
pages = {215-224},
abstract = {In estuarine systems, informed water resource management decisions rely, in part, on bow in freshwater inflow and salinity affect a selected management target habitat changes). This examined the distribution of altemiflora and S. cynosuriodes the Altamaha River estuary in in association with an extensive during which time freshwater inflow decreased and salty water encroached into previollsly brackish areas. Bankside was of the estuary at the and end of the drought (2000. and again in 2004 after flows had increased. In addition, a removal which one or the other plant was removed from naturally mixed communities, was conducted drought (2001-2002). In all surveys, S. cynosuroides densities decreased at a location that to where average high tide salinities were> 14 psu, such that the downstream border shifted from approximately 3 to 6 km from the mouth of the river between 2000 and 2002 and then back to 3 km in 2004. Although the of S. altemiflora also shifted upstream between 2000 and 2002, upstream densities were in 2004 and distribution did not with In the removal densities and relative \% cover of S. increased in all treatments Vrl(}SU,rlJ"{\textquoteright}WS remained constant except in treatments where it was removed. Ve these results to suggest that S. is a strong invader that can into new habitat under stressful salinity, low flow) conditions, and that once it is established it can co-exist with S. The more response of S. cynosuroides (shifts occurred within 2 suggests that its downstream limit is a indicator of in inflow conditions in this system.},
keywords = {altamaha river, drought, GCE, spartina},
doi = {10.1672/08-39.1},
url = {http://www.bioone.org/doi/abs/10.1672/08-39.1},
author = {White, Susan N. and Alber, Merryl.}
@article {66129,
title = {Ecosystem development of a sandbar emergent tidal marsh, Altamaha River estuary, Georgia USA},
journal = {Wetlands},
volume = {29},
year = {2009},
pages = {314-322},
abstract = {Vegetation structure and soil properties were measured on a sandbar, a three year old sandbar emergent marsh (SEM), and five mature Spartina alterniflora Loisel marshes located near the mouth of the Altamaha River (Georgia, USA) to determine how quickly tidal marsh vegetation and soils develop during primary succession. Those data were compared to published data collected from young (10},
keywords = {ecosystem, emerged, GCE, sapelo island, tidal marsh},
doi = {10.1672/06-178.1},
url = {http://www.bioone.org/doi/abs/10.1672/06-178.1},
author = {Krull, Kandy. and Craft, Christopher B.}
@article {66149,
title = {Effects of nitrogen and phosphorus additions on primary production and invertebrate densities in a Georgia (USA) tidal freshwater marsh.},
journal = {Wetlands},
volume = {29},
year = {2009},
pages = {196-203},
abstract = {We added nitrogen (N), phosphorus (P), and N+P to a Zizaniopsis miliacea (Giant Cutgrass) dominated tidal freshwater marsh in Georgia USA to investigate nutrient limitation of tidal freshwater marsh primary production and invertebrate densities. After two years, aboveground biomass was significantly greater in the plots receiving N (2130 g m-2), and N+P (2066 g m-2) than in the control (886 g m-2) and P (971 g m-2) only treatments. We observed no enrichment of leaf N or P in response to nutrient additions. Rather leaf N decreased and CN increased in plots receiving N, suggesting that leaf N was diluted by increased production of carbon laden structural components used to support increased plant height. NP ratios (molmol) of the plant tissue were consistently < 30 (14},
keywords = {GCE, nitrogen, phosphorus, plant production, salt marsh, tidal marsh},
doi = {10.1672/07-79.1},
url = {http://www.bioone.org/doi/abs/10.1672/07-79.1},
author = {Frost, Josh W. and Schleicher, Tymeri. and Craft, Christopher B.}
@article {66176,
title = {Evidence for impacts of non-indigenous macroalgae: a meta-analysis of experimental field studies},
journal = {Journal of Phycology},
volume = {45},
year = {2009},
pages = {812-819},
abstract = {Invasions by nonindigenous macroalgal species (NIMS) potentially cause severe impacts on native species. We conducted a meta-analysis of 18 field-based manipulative experiments to quantify the direction and magnitude of impacts (Hedges effect size d, hereafter ES). We found significant small-to-medium negative effects on},
keywords = {algae, GCE, invasive species, meta-analysis},
doi = {10.1111/j.1529-8817.2009.00709.x},
url = {http://onlinelibrary.wiley.com/doi/10.1111/j.1529-8817.2009.00709.x/pdf},
author = {Thomsen, Mads S. and Wernberg, T and Tuya, F. and Silliman, Brian R.}
@article {66199,
title = {Forecasting the effects of accelerated sea level rise on tidal marsh ecosystem services},
journal = {Frontiers in Ecology and the Environment},
volume = {7},
year = {2009},
pages = {73-78},
abstract = {We used field and laboratory measurements, geographic information systems, and simulation modeling to investigate the potential effects of accelerated sea-level rise on tidal marsh area and delivery of ecosystem services along the Georgia coast. Model simulations using the Intergovernmental Panel on Climate Change (IPCC) mean and maximum estimates of sea-level rise for the year 2100 suggest that salt marshes will decline in area by 20\% and 45\%, respectively. The area of tidal freshwater marshes will increase by 2\% under the IPCC mean scenario, but will decline by 39\% under the maximum scenario. Delivery of ecosystem services associated with productivity (macrophyte biomass) and waste treatment (nitrogen accumulation in soil, potential denitrification) will also decline. Our findings suggest that tidal marshes at the lower and upper salinity ranges, and their attendant delivery of ecosystem services, will be most affected by accelerated sealevel rise, unless geomorphic conditions (ie gradual increase in elevation) enable tidal freshwater marshes to migrate inland, or vertical accretion of salt marshes to increase, to compensate for accelerated sea-level rise.},
keywords = {climate change, ecosystem services, GCE, sea level rise, signature publication, tidal marshes},
doi = {10.1890/070219},
url = {http://www.esajournals.org/doi/abs/10.1890/070219},
author = {Craft, Christopher B. and Clough, J. and Ehman, J. and Joye, Samantha B. and Park, R. and Pennings, Steven C. and Guo, Hongyu. and Machmuller, Megan.}
@inbook {66210,
title = {From climate change to snails: potential causes of salt marsh die-back along the U.S. Eastern Seaboard and Gulf Coasts},
booktitle = {Human Impacts on Salt Marshes: A Global Perspective},
year = {2009},
pages = {231-252},
publisher = {University of California Press},
organization = {University of California Press},
keywords = {climate change, dieback, GCE, invertebrates, molluscs, salt marsh, snails},
author = {Osgood, D. and Silliman, Brian R.},
editor = {Bertness, Mark D.}
@inbook {66214,
title = {Global change and tidal freshwater wetlands: Scenarios and impacts},
booktitle = {Tidal Freshwater Wetlands},
year = {2009},
pages = {253-310},
publisher = {Backhuys Publishers},
organization = {Backhuys Publishers},
address = {Leiden, The Netherlands},
keywords = {climate change, climatology, freshwater, GCE, global change, tide, wetland},
author = {Neubauer, S.C. and Craft, Christopher B.},
editor = {Baldwin, A.H.}
@article {66219,
title = {Grazer facilitation of fungal infection and the control of plant growth in south-western Atlantic salt marshes},
journal = {Journal of Plant Ecology},
volume = {97},
year = {2009},
pages = {781-787},
abstract = {While great effort has been made in documenting the processes that drive plant-induced susceptibility after herbivore attack and it is widely accepted that herbivores can facilitate plant diseases, the relative importance of this interaction in controlling plant growth in natural systems remains largely unexplored.2. In south-western Atlantic salt marshes, we investigated the importance of disease after herbivory by examining: (i) whether or not a herbivorous crab facilitates disease (i.e. fungus infection) in marsh plants (Spartina alterniflora and S. densiflora) when clipping off small portions of leaves and (ii) the separate and interactive effects of crab grazing but fungal infection in controlling marsh plant growth.3.Our results show that crab grazing facilitates fungal infection in Spartina leaves. A factorial field experiment shows that both direct crab herbivory and fungal infection strongly suppress plant production (by more than 50\%).4.Synthesis. These experimental results demonstrate that fungal infection following herbivory attack can decrease salt marsh plant production and that increased disease susceptibility can be a fundamental factor in controlling plant production in natural ecosystems, even in cases where herbivores do not directly inoculate the pathogen but only damage plant tissue.},
keywords = {facilitation, fungal infection, GCE, herbivory, plant production, salt marshes, spartina, top-down control},
doi = {10.1111/j.1365-2745.2009.01508.x},
url = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2745.2009.01508.x/abstract},
author = {Daleo, P. and Silliman, Brian R. and Alberti, J. and Escapa, M. and Canepuccia, A. and Pena, N. and Iribarne, O.}
@article {66226,
title = {Habitat-specific decomposition of saltmarsh detritus along a marine-terrestrial gradient},
year = {2009},
keywords = {decomposition, detritivorous soil fauna, GCE, marine-terrestrial ecotone, saltmarsh},
author = {Seer, Franziska. and Putze, Gregor. and Pennings, Steven C. and Zimmer, Martin.}
@article {66273,
title = {Interspecific interactions in the decomposition of common saltmarsh detritus},
year = {2009},
keywords = {armases, decomposition, GCE, juncus, littoraria, melampus, quercus, spartina, synergistic interaction},
author = {Mews, Malte. and Pennings, Steven C. and Zimmer, Martin.}
@article {66275,
title = {Intra-guild predator/prey-interactions promote decomposition of low-quality detritus in a saltmarsh system},
year = {2009},
abstract = {Intra-guild facilitation among detritivores is expected to promote decomposition processes. On the other hand, intra-guild predation of omnivorous predators on detritivores will reduce detritivore-mediated decomposition rates. To this end, it is surprising that relatively little attention has thus far been paid to omnivorous detritivores that also prey on other detritivores. We investigated the spatial subsidy of litter with a terrestrial origin provided by trees located on the terrestrial fringe of saltmarshes, and how its decomposition is affected by intra-guild interactions of detritivorous snails and omnivorous crabs. In field mesocosms, we studied whether decomposition of leaf and needle litter of live oak (Quercus virginiana) and loblolly pine (Pinus taeda) was affected by saltmarsh detritivores (Gastropoda: Littoraria irrorata and Melampus bidentatus) and predacious omnivores (Decapoda: Armases cinereum). Both crabs and snails alone increased decomposition (mass loss) rates of oak litter, while a combination of both resulted in the same mass loss as in animal-free controls, probably due to crabs feeding on snails rather than litter. Neither crabs nor snails alone affected mass loss of pine litter, but a combination of both significantly increased decomposition rates. Irrespective of the litter type, crabs increased mortality of the snails but gained biomass only on pine litter and only when detritivorous snails were present. Our findings indicate that detritivorous prey organisms (snails) increase the nutritive value of a terrestrial food source (pine litter) to the omnivorous saltmarsh crab Armases. Unidirectional facilitation of crabs by snails promotes the decomposition of this low-quality litter. On a terrestrial food source of intermediate quality (oak litter), negative effects of the predator prevail, resulting in a drop of decomposition rates when crabs were present, probably owing to increased mortality of detritivorous snails.},
keywords = {decomposition processes, GCE, intra-guild predation, omnivory, saltmarsh, trophic interactions},
author = {Ewers, Christine. and Beiersdorf, Anika. and Wieski, Kazimierz. and Pennings, Steven C. and Zimmer, Martin.}
@inbook {66278,
title = {An introduction to human impacts on salt marshes: Are marshes at risk?},
booktitle = {Human Impacts on Salt Marshes: A Global Perspective},
year = {2009},
publisher = {University of California Press},
organization = {University of California Press},
keywords = {GCE, human impacts, risk, salt marsh},
author = {Silliman, Brian R. and Grosholtz, T. and Bertness, Mark D.},
editor = {Bertness, Mark D.}
@article {66300,
title = {Latitudinal variation in herbivore pressure in Atlantic Coast salt marshes},
journal = {Ecology},
volume = {90},
year = {2009},
pages = {183-195},
abstract = {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 \&$\#$8805;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.},
keywords = {biogeography, community, ecology, GCE, herbivory, latitude, plants, salt marsh},
doi = {10.1890/08-0222.1},
url = {http://www.esajournals.org/doi/pdf/10.1890/08-0222.1},
author = {Pennings, Steven C. and Ho, Chuan-Kai. and Salgado, Cristiano S. and Wieski, Kazimierz. and Dav and Kunza, Amy E. and Wason, Elizabeth L.}
@article {66314,
title = {The Long-Term Ecological Research community metadata standardisation project: a progress report},
journal = {International Journal of Metadata, Semantics and Ontologies},
volume = {4},
year = {2009},
pages = {141-153},
keywords = {AND, ARC, BES, BNZ, CCE, GCE, HBR, LNO, LUQ, PIE, SBC, SEV},
doi = {10.1504/IJMSO.2009.02775},
author = {San Gil, Inigo. and Melendez, E. and Walsh, J.M. and Kortz, M. and Conners, J. and Yarmey, L. and Kaplan, N. and Boose, E.R. and Powell, L. and Gries, C. and Schroeder, R. and Baker, K.S. and Ackerman, T. and Ramsey, K. and Benson, B. and Chipman, J. and Laundre, J.A. and Garritt, H. and Henshaw, D.L. and Collins, B. and Gardner, C and Bohm, S. and Campbell, J. and OBrien, M. and Gao, J. and Sheldon, W. and Lyon, S. and Bahauddin, D. and Servilla, M and Costa, D and Brunt, J. W. and Denny, E. G. and Vanderbilt, Kristin L. and Riordan, B. and Koskela, R.K. and Downing, J. P. and Grabner, S.}
@article {66331,
title = {Microbial Community Response to Seawater Amendment in Low-Salinity Tidal Sediments},
journal = {Microbial Ecology},
volume = {58},
year = {2009},
pages = {558-568},
abstract = {Rising sea levels and excessive water withdrawals upstream are making previously freshwater coastal ecosystems saline. Plant and animal responses to variation in the freshwater-saline interface have been well studied in the coastal zone; however, microbial community structure and functional response to seawater intrusion remains relatively unexplored. Here, we used molecular approaches to evaluate the response of the prokaryotic community to controlled changes in porewater salinity levels in freshwater sediments from the Altamaha River, Georgia, USA. This work is a companion to a previously published study describing results from an experiment using laboratory flow-through sediment core bioreactors to document biogeochemical changes as porewater salinity was increased from 0 to 10 over 35 days. As reported in Weston et al. (Biogeochemistry, 77:375-408, 62), porewater chemistry was monitored, and cores were sacrificed at 0, 9, 15, and 35 days, at which time we completed terminal restriction fragment length polymorphism and 16S rRNA clone library analyses of sediment microbial communities. The biogeochemical study documented changes in mineralization pathways in response to artificial seawater additions, with a decline in methanogenesis, a transient increase in iron reduction, and finally a dominance of sulfate reduction. Here, we report that, despite these dramatic and significant changes in microbial activity at the biogeochemical level, no significant differences were found between microbial community composition of control vs. seawater-amended treatments for either Bacterial or Archaeal members. Further, taxa in the seawater-amended treatment community did not become more "marine-like" through time. Our experiment suggests that, as seawater intrudes into freshwater sediments, observed changes in metabolic activity and carbon mineralization on the time scale of weeks are driven more by shifts in gene expression and regulation than by changes in the composition of the microbial community.},
keywords = {biogeochemistry, community, GCE, microbial ecology, sediments},
doi = {10.1007/s00248-009-9556-2},
url = {http://www.springerlink.com/content/44411m5237863955/},
author = {Edmonds, Jennifer W. and Weston, Nathaniel B. and Joye, Samantha B. and Mou, Xiaozhen. and Moran, Mary Ann.}
@article {66334,
title = {Microzooplankton growth and trophic interactions and their effects on herbivory in coastal and offshore environments.},
journal = {Aquatic Microbial Ecology},
volume = {54},
year = {2009},
pages = {255-267},
abstract = {We performed serial dilution experiments to estimate rates of gross phytoplankton growth (},
keywords = {ciliates, dinoflagellates, food web model, GCE, microbial food web, microplankton, serial dilution experiments, trophic cascades, zooplankton},
doi = {10.3354/ame01271},
url = {http://dx.doi.org/10.3354/ame01271},
author = {First, Matthew R. and Miller, H. L and Lavrentyev, Peter J. and Pinckney, James L. and Burd, Adrian B.}
@article {66340,
title = {The model high molecular weight DOC compound, dextran, is ingested by the benthic ciliate, Uronema marinum, but does not supplement ciliate growth},
journal = {Aquatic Microbial Ecology},
volume = {57},
year = {2009},
pages = {79-87},
abstract = {Phagotrophic ciliates are capable of growth solely on dissolved compounds. Whether ciliates use dissolved compounds in the environment for growth is unclear. We investigated the ability of the marine benthic ciliate, Uronema marinum, to ingest a model high molecular weight dissolved organic carbon (HMW-DOC) compound, dextran, at concentrations typical for coastal salt marsh sediments (3},
keywords = {benthic food web, carbohydrates, cell metabolism, ciliate, GCE, microbenthos, pinocytosis},
doi = {10.3354/ame01338},
url = {http://dx.doi.org/10.3354/ame01338},
author = {First, Matthew R. and Hollibaugh, James T.}
@article {66361,
title = {Natural Attenuation Of Nitrogen Loading From Septic Effluents: Spatial And Environmental Controls},
journal = {Water Research},
volume = {44},
year = {2009},
pages = {1399-1408},
abstract = {We assess the role of septic systems as potential nitrogen (N) sources to coastal open water bodies. To quantify the potential role of septic tanks, we document the distribution pattern and functionality of septic tanks in McIntosh County in Georgia, USA, and examine factors governing the mitigation of septic N loading in coastal groundwater. Employing a field calibrated 2D variable-density reaction-transport model, we focus on the role of setback distance of a leaky septic source from the receiving surface waters, on transport and biogeochemical characteristics of the subsurface environment, and on leachate composition and reactivity. We conclude that the removal of bioavailable nitrogen via denitrification may be increased by increasing the septic system setback distance, in particular in brackish and saline coastal settings where sulfide produced in sulfate reduction can limit N2 production.},
keywords = {coastal eutrophication, denitrification, GCE, nitrogen transformation, septic tank, sulfide inhibition},
doi = {10.1016/j.watres.2009.11.019},
author = {Meile, Christof. and Porubsky, William P. and Walker, R.L. and Payne, Karen.}
@article {66376,
title = {Non-linearity in ecosystem services: temporal and spatial variability in coastal protection},
journal = {Frontiers in Ecology and the Environment},
volume = {7},
year = {2009},
pages = {29-37},
abstract = {Natural processes tend to vary over time and space, as well as between species. The ecosystem services these natural processes provide are therefore also highly variable. It is often assumed that ecosystem services are provided linearly (unvaryingly, at a steady rate), but natural processes are characterized by thresholds and limiting functions. In this paper, we describe the variability observed in wave attenuation provided by marshes, mangroves, seagrasses, and coral reefs and therefore also in coastal protection. We calculate the economic consequences of assuming coastal protection to be linear. We suggest that, in order to refine ecosystem-based management practices, it is essential that natural variability and cumulative effects be considered in the valuation of ecosystem services},
keywords = {ecology, ecosystem services, GCE, variability},
doi = {10.1890/080126},
url = {http://www.esajournals.org/doi/abs/10.1890/080126},
author = {Koch, Evamaria W. and Polasky, Stephen. and Halpern, Benjamin S. and Kennedy, Christopher J. and Kappel, Carrie V. and Wolanski, Eric. and Barbier, Edward B. and Silliman, Brian R. and Reed, Denise J. and Perillo, M. E. and Hacker, Sally D. and Granek, Elise F. and Primavera, Jurgenne H. and Muthiga, Nyawira.}
@inbook {66401,
title = {Patterns of salt marsh loss within coastal regions of North America: pre-settlement to present},
booktitle = {Human Impacts on Salt Marshes: A Global Perspective},
year = {2009},
pages = {253-266},
publisher = {University of California Press},
organization = {University of California Press},
keywords = {disturbance, GCE, paleoecology, salt marsh},
author = {Bromberg, Keryn. and Silliman, Brian R.},
editor = {Bertness, Mark D.}
@article {66422,
title = {Plasticity, Not Adaptation to Salt Level, Explains Variation Along a Salinity Gradient in a Salt Marsh Perennial},
journal = {Estuaries and Coasts},
volume = {33},
year = {2009},
pages = {840-852},
abstract = {Evolutionary ecologists have long been intrigued by the fact that many plant species can inhabit a broad range of environmental conditions and that plants often exhibit dramatic differences in phenotype across environmental gradients. We investigated responses to salinity treatments in the salt marsh plant Borrichia frutescens to determine if the species is responding to variation in edaphic salt content through phenotypic plasticity or specialized trait response. We grew seedlings from fruits collected in high- and low-salt microhabitats, assigned seedlings to high- and low-salt treatments in a greenhouse, and measured traits related to salt tolerance. All traits were highly plastic in response to salinity. Plants from the two microhabitats did not differ in trait means or respond differently to the treatments. These results suggest that environmental differences between the two microhabitats are not creating genotypes adapted to high and low salt levels. In addition, despite evidence for variation in allozyme markers in this population, there was no significant genotypic variation (family effect) in any of the trait means measured across microhabitats. There was variation in plasticity for only leaf Na and leaf B concentration. The high degree of plasticity for all traits and the lack of differences among microhabitats across the salinity gradient suggest plasticity in many traits may be fixed for this species.},
keywords = {GCE, marsh, plants, plasticity, salinity, salt, variability},
doi = {10.1007/s12237-009-9186-4},
url = {http://www.plantbio.uga.edu/~donovan/Publication\%20PDFs/Richards\%20et\%20al.\%20Estuaries\%20\&\%20Coasts\%202009.pdf},
author = {Richards, Christina L. and White, Susan N. and McGuire, Mary Anne. and Franks, Steven J. and Donovan, Lisa A. and Mauricio, Rodney.}
@article {66424,
title = {Population growth away from the coastal zone: Thirty years of land use change and nutrient export from the Altamaha River, GA},
journal = {Science of the Total Environment},
volume = {407},
year = {2009},
pages = {3347-3356},
abstract = {We used more than thirty years of water quality monitoring data collected by the United States Geological Survey at several stations in the Altamaha River and its tributaries to examine the relationship between population density, agricultural land use, and nutrient export from the watershed. Population densities in the Altamaha River watershed increased during the study period, most notably in the upper watershed near metropolitan Atlanta, while agricultural land use declined throughout the watershed. NOx, TN and P in rivers were related to human population densities, while OC and NH+4 concentrations in rivers were apparently related to agricultural land use. A general pattern of increasing NOx and TN and decreasing NH4+, P and OC over time throughout the watershed reflected changing population and land use. The overall average load from the Altamaha River to the coastal zone during the study period was 1.1, 5.6,16.9,0.9 and 262 kmol km-2 yr-1, delivering 40,197, 596, 30, and 9213 106 mol yr-1 of NH4+, NOx, TN, P and OC, respectively, to the coastal zone. The nutrient export patterns suggest that N and P loading to rivers in the Altamaha River watershed was greatest in the upper watershed where high population densities were found, and in-stream processing, dilution, and only moderate inputs during transit through the lower watershed resulted in relatively low export from the watershed to coastal waters.},
keywords = {altamaha river, GCE, LOADING, nutrient, organic carbon, watershed},
doi = {10.1016/j.scitotenv.2008.12.066},
url = {http://dx.doi.org/10.1016/j.scitotenv.2008.12.066},
author = {Weston, Nathaniel B. and Hollibaugh, James T. and Joye, Samantha B.}
@article {66442,
title = {A re-assessment of the ecology of the so-called saltmarsh crab Armases cinereum},
year = {2009},
keywords = {digestive enzymes, FEEDING PREFERENCE, GCE, gut microbiota, habitat, marine-terrestrial ecotone, migration, saltmarsh, stable isotopes},
author = {Huebner, Lena. and Pennings, Steven C. and Zimmer, Martin.}
@inbook {66479,
title = {Salt marshes under global siege},
booktitle = {Human Impacts on Salt Marshes: A Global Perspective},
year = {2009},
pages = {391-398},
publisher = {University of California Press},
organization = {University of California Press},
keywords = {disturbance, ecology, GCE, salt marsh},
author = {Silliman, Brian R. and Grosholtz, T. and Bertness, Mark D.},
editor = {Bertness, Mark D.}
@inbook {66498,
title = {Shoreline development and the future of New England salt marsh landscapes},
booktitle = {Human Impacts on Salt Marshes: A Global Perspective},
year = {2009},
pages = {137-148},
publisher = {University of California Press},
organization = {University of California Press},
keywords = {development, ecology, GCE, landscape, salt marsh},
author = {Bertness, Mark D. and Silliman, Brian R. and Holdredge, Christine.},
editor = {Bertness, Mark D.}
@article {66503,
title = {SLR and ecosystem services: a response to Kirwan and Guntenspergen.},
journal = {Frontiers in Ecology and the Environment},
volume = {7},
year = {2009},
pages = {127-128},
keywords = {cimate change, ecosystem services, GCE, salt water intrusion, sea level rise, tidal marshes},
url = {http://gce-lter.marsci.uga.edu/public/uploads/Craft_et_al_2009_Writeback_20120221T135811.pdf},
author = {Craft, Christopher B. and Clough, J. and Ehman, J. and Joye, Samantha B. and Park, R. and Pennings, Steven C. and Guo, Hongyu. and Machmuller, Megan.}
@inbook {66545,
title = {Tidal marsh creation},
booktitle = {Coastal Wetlands},
year = {2009},
pages = {715-786},
publisher = {Elsevier},
organization = {Elsevier},
address = {Amsterdam, The Netherlands},
keywords = {GCE, salt marsh, tidal},
url = {http://www.elsevier.com/wps/find/bookdescription.cws_home/716674/description},
author = {Broome, S. W. and Craft, Christopher B.},
editor = {Brinson, M. M.}
@inbook {66547,
title = {Top-down control and human intensification of consumer pressure in southern U.S. salt marshes},
booktitle = {Human Impacts in Salt Marshes: A Global Perspective},
year = {2009},
pages = {103-114},
publisher = {University of California Press},
organization = {University of California Press},
address = {Berkeley, California},
keywords = {ecology, GCE, human consumer, salt marsh, top-down},
url = {http://books.google.com/books?id=dZbvgaYT6JYC\&lpg=RA1-PA391\&ots=LjWVzcJu4D\&dq=Salt\%20Marshes\%20Under\%20Global\%20Siege\&pg=PP6$\#$v=onepage\&q=Salt\%20Marshes\%20Under\%20Global\%20Siege\&f=false},
author = {Silliman, Brian R. and Bertness, Mark D. and Thomsen, Mads S.},
editor = {Bertness, Mark D.}
@article {66550,
title = {Transport and dispersion of a conservative tracer in coastal waters with large intertidal areas},
journal = {Estuaries and Coasts},
volume = {32},
year = {2009},
pages = {573-592},
abstract = {In late December 1991, an accidental release of 5,700 CI of tritiated water (HTO) from the Savannah River Site was transported via site streams into the Savannah River where it was carried downstream to the coastal zone. HTO released into a semitropical Georgia estuary was forced into the tidal marshes surrounding the estuary as well as discharged directly into the Atlantic Ocean. The spreading of HTO was studied with a 3D hydrodynamic model (ALGE) that includes flooding and draining of intertidal areas. Comparisons of model simulations to measured HTO concentration showed that ALGE simulated well the general increase and decrease of HTO as its plume passed a given area. The},
keywords = {conservativetracers, GCE, hydrodynamic modeling, tritium},
doi = {10.1007/s12237-009-9141-4},
url = {http://www.springerlink.com/content/772817k644w71071/},
author = {Blanton, Jackson O. and Garrett, A. and Bollinger, J. and Hayes, D. and Koffman, L. and Amft, Julie.}
@article {66572,
title = {Using Facilitation Theory to Enhance Mangrove Restoration},
journal = {Ambio},
volume = {38},
year = {2009},
pages = {109},
abstract = {Despite advances in positive interactions and facilitation theory in ecological research (1, 2), the concepts have failed to make a big impact on mangrove restoration ecology. Restoration applications of facilitation include reaping the community benefits of foundation species, positive density dependence, and facilitation cascades (3). In their June 2008 article,},
keywords = {ecology, GCE, mangrove, restoration},
doi = {10.1579/0044-7447-38.2.109},
url = {http://www.bioone.org/doi/pdf/10.1579/0044-7447-38.2.109},
author = {Bromberg-Gedan, Keryn. and Silliman, Brian R.}
@article {66587,
title = {Watershed nitrogen input and riverine export on the west coast of the U.S.},
journal = {Biogeochemistry},
volume = {93},
year = {2009},
pages = {219-233},
abstract = {This study evaluated the sources, sinks, and factors controlling net export of nitrogen from watersheds on the west coast of the US. We calculated input of new N to 22 watersheds for 1992 and 2002. 1992 inputs ranged from 541-11,644 kg N km-2 yr-1, with an overall area-weighted average of 1,870 kg N km-2 yr-1. In 2002, the range of inputs was 490-10,875 kg N km-2 yr-1, averaging 2,158 kg N km-2 yr-1. Fertilizer was the most important source of new N, averaging 956 (1992) and 1,073 kg N km-2 yr-1 (2002). Atmospheric deposition was the next-most important input, averaging 833 (1992) and 717 kg N km-2 yr-1 (2002), followed by biological N fixation in agricultural lands. Riverine N export, calculated based on measurements taken at the furthest downstream USGS water quality monitoring station, averaged 165 (1992) and 196 kg N km-2 yr-1 (2002), although data were available for only 7 watersheds at the latter time point. Downstream riverine N export was correlated with variations in streamflow (export=0.94*streamflow-5.65, R2=0.66), with N inputs explaining an additional 16\% of the variance (export=1.06*streamflow+0.06*input},
keywords = {GCE, nitrogen budgets, nutrient inputs, riverine export, watersheds, west coast},
doi = {10.1007/s10533-009-9299-7},
url = {http://www.springerlink.com/content/n3813vng61jr4572/},
author = {Schaefer, Sylvia C. and Hollibaugh, James T. and Alber, Merryl.}
@article {66613,
title = {Air-sea CO2 fluxes on the US South Atlantic Bight: Spatial and temporal variability},
journal = {Journal of Geophysical Research-Ocean},
volume = {113},
year = {2008},
pages = {C07019},
abstract = {The partial pressure of carbon dioxide (pCO2) in surface seawater on the South Atlantic Bight (SAB) of the United States was measured during six cruises from January 2005 to May 2006. The high-resolution pCO2 data allow us to create the first maps of the sea surface pCO2 over the SAB for all seasons. Contrary to an earlier study that was based on limited spatial and seasonal coverage, this study shows that the SAB is a net sink of atmospheric CO2 on an annual basis (-0.48},
keywords = {atmosphere, carbon dioxide, CO2, GCE, south atlantic bight, variability},
doi = {10.1029/2007JC004366},
url = {http://www.agu.org/journals/jc/jc0807/2007JC004366/},
author = {Jiang, Liqing. and Cai, Wei-Jun. and Wang, Yongchen. and Wanninkhof, R. and Luger, H.}
@mastersthesis {66638,
title = {Benthic Microbial Food Webs: Spatial and Temporal Variations and the Role of Heterotrophic Protists in Salt Marsh Sediments},
year = {2008},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {In order to determine if the loss of bacterial biomass varies over time, I investigated the microbial food web structure at two time scales in the salt marsh sediments of Sapelo Island, Georgia. Samples were collected monthly for one year at three contrasting subtidal locations: a high energy sandy beach, a muddy Spartina marsh, and a tidal creek bed. Concentrations of benthic microalgae (BMA), bacteria, heterotrophic protists, and metazoan meiofauna were measured at each location. Additionally, short-term dynamics of sediment microbial populations and bacterivory rates were investigated over a diel period in an intertidal creek bed to determine if variable rates of protist grazing could significantly impact bacterial standing stock. Although bacterivory rates were variable throughout the day, there were no periods of the day when protists could effectively reduce bacterial biomass. Yearly sampling revealed high variation in the microbial food web structure, mostly among sample locations. However, I observed a shift from a BMA-dominated community in the spring/ early summer months to a bacterial-dominated food web in the late summer/fall at all locations. Bacteria and heterotrophic protist concentrations were significantly related to porewater volume (6.9},
keywords = {GCE, microbial ecology, protists, salt marsh, sediments},
url = {http://gce-lter.marsci.uga.edu/public/uploads/first_matthew_r_200805_phd_20090909T164044.pdf},
author = {First, Matthew R.}
@mastersthesis {66644,
title = {Biogeochemical dynamics in coastal sediments and shallow aquifers},
year = {2008},
pages = {222},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {Patterns of benthic metabolism and the relative importance of assimilatory and dissimilatory processes as sinks for nitrate (NO3-) in intertidal sediments were examined. Under illuminated, nitrogen (N)-replete conditions, sequential nutrient limitation of benthic microalgae (BMA) was observed, with N limitation preceding silicate limitation; and biological assimilation dominated nitrate uptake. Conversely, under dark hypoxic and anoxic conditions, water column NO3- uptake was dominated largely by three competing dissimilatory reductive processes; denitrification (DNF), dissimilatory nitrate reduction to ammonium (DNRA), and, on one occasion, anaerobic ammonium oxidation (anammox). High sulfide concentrations negatively impacted DNF and DNRA rates, while high dissolved organic carbon (DOC):NO3- ratios favored DNRA over DNF. Under baseline conditions sediments exhibited tight coupling between photosynthesis and respiration. Nitrogen addition shifted the metabolic status of the sediments from a balance between autotrophy and heterotrophy to net autotrophy, and the sediments became a source of DOC. The role of groundwater as a source of nutrients and organics to the coastal ocean was evaluated using a combination of radium isotopes and geochemical characterization. Geochemical data indicated significant spatial variations in groundwater chemical composition and radium activity ratios indicated geographically distinct hydrological regimes. Spatial variations in microbially mediated processes, DOC distribution, and/or groundwater residence time contributed to this pattern. Radium based geochemical loading rates illustrated a substantial groundwater contribution of organics, DIC, nutrients, methane and nitrous oxide to the Okatee estuary. The groundwater biogeochemical dynamics along a shallow monitoring well transect on a coastal hammock were evaluated by density-dependent reaction transport model. A switch in the redox status of the DIN pool occurred during the spring-neap tidal transition (spring high NO3- low NH4+; neap low NO3- high NH4+). The observed N redox-switch was evaluated with regard to the relative roles of nitrification, DNF, DNRA, ammonium adsorption, and variations in inflowing water geochemistry between spring and neap tides. The latter was found to most significantly affect the observed pattern in DIN dynamics. Additionally, the fate of DOC and DIN originating from a septic system was studied. Simulation results indicated that while DNF increased ~15 fold, higher N removal rates could not keep pace with the increase in DIN loading, resulting in higher export of DIN to coastal waters.},
keywords = {ammonium, anaerobic ammonium oxidation, benthic fluxes, benthic microalgae, biogeochemistry, denitrification, dissimilatory nitrate reduction, dissolved organic carbon, GCE, groundwater, intertidal sediments, nitrogen, nutrients, sediment-water column exchange},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/Porubsky_William_P_200812_PhD.pdf},
author = {Porubsky, William P.}
@mastersthesis {66670,
title = {Centrifugal organization in a Georgia salt marsh plant community},
year = {2008},
pages = {67},
school = {University of Houston},
address = {Houston, Texas},
abstract = {In this study I evaluate whether a centrifugal model helps explain vegetation patterns in a Georgia salt marsh using a combination of sampling data and manipulative experiments. The centrifugal model predicts that multiple stress gradients radiate out from a shared core habitat and that plants should occupy discrete ranges along these gradients. The results from this study indicated that there were two clear stress gradients, salinity and water-logging, along which species and habitats occupied discrete ranges, supporting the centrifugal model. The centrifugal model predicts that productivity should be greatest at the benign end of each stress gradient and least at the most stressful end. The results from this study generally supported the centrifugal model. Juncus and Borrichia, which occupied the most benign habitat, had the highest biomass. The stressful ends of the gradients, occupied by Salicornia virginica, short Spartina alterniflora and medium Spartina alterniflora, all had relatively low biomass. The centrifugal model predicts that diversity should be highest in intermediate levels of stress. Salicornia virginica and Spartina alterniflora zones always had the lowest species richness and diversity, supporting the centrifugal model. However, the Borrichia zone always had the greatest or second greatest level of species richness and diversity, not supporting the centrifugal model. The centrifugal model predicts that when species are transplanted outside of the benign habitat they will do poorly, with or without neighbors present, where species at the stressful ends of the gradients will do well when transplanted into the benign habitat without neighbors, but poorly when neighbors are present. The results of the transplant experiments strongly supported the centrifugal model. In conclusion, I found strong evidence that the centrifugal model was useful in explaining plant community structure in a Georgia salt marsh. This model also provides a unified theory for vegetation patterns in northeast and southeast USA salt marshes, where zonation due to high salinities caused by increased evapotranspiration in the low-latitude climates can be equated to the disturbance-caused temporary increases in salinity in high-latitude climates.},
keywords = {community ecology, GCE, georgia, plants, salt marsh, sapelo island},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/ALynes_MS_Thesis_2008.pdf},
author = {Lynes, Alana R.}
@article {66708,
title = {A comparative study of carbon dioxide degassing in river- and marine-dominated estuaries},
journal = {Limnology and Oceanography},
volume = {53},
year = {2008},
pages = {2603-2615},
abstract = {The partial pressure of carbon dioxide (pCO2), concentration of total dissolved inorganic carbon (DIC) and total alkalinity (TA) were measured at both high tide and low tide in the surface water of three Georgia (United States of America) estuaries from September 2002 to May 2004. Of the three estuaries, Sapelo and Doboy Sounds are marine-dominated estuaries, while Altamaha Sound is a river-dominated estuary. During all sampling months, the three estuaries were supersaturated in CO2 with respect to the atmosphere (39.5-342.5 Pa, or 390 - 3380},
keywords = {air-water fluxes, carbon dioxide, estuaries, GCE, marine-dominated, river-dominated},
url = {http://gce-lter.marsci.uga.edu/public/uploads/Jiang_et_al._2008b_20081111T84730.pdf},
author = {Jiang, Liqing. and Cai, Wei-Jun. and Wang, Yongchen.}
@article {66720,
title = {Consequences of omnivory for trophic interactions on a salt-marsh shrub},
journal = {Ecology},
volume = {89},
year = {2008},
pages = {1714-1722},
abstract = {Although omnivory is common in nature, its impact on trophic interactions is variable. Predicting the food web consequences of omnivory is complicated because omnivores can simultaneously produce conflicting direct and indirect effects on the same species or trophic level. We conducted field and laboratory experiments testing the top-down impacts of an omnivorous salt marsh crab, Armases cinereum, on the shrub Iva frutescens and its herbivorous and predatory arthropod fauna. Armases is a},
keywords = {ecology, GCE, omnivory, plant, shrub, trophic interactions},
doi = {10.1890/07-1069.1},
url = {http://www.esajournals.org/perlserv/?request=get-abstract\&doi=10.1890\%2F07-1069.1\&ct=1},
author = {Ho, Chuan-Kai. and Pennings, Steven C.}
@article {66721,
title = {Consumer Control of Salt Marshes Driven by Human Disturbance},
journal = {Conservation Biology},
volume = {22},
year = {2008},
pages = {618-623},
abstract = {Salt marsh ecosystems are widely considered to be controlled exclusively by bottom},
keywords = {consumer, disturbance, dogma, GCE, human, salt marsh},
doi = {10.1111/j.1523-1739.2008.00962.x},
author = {Bertness, Mark D. and Silliman, Brian R.}
@article {66740,
title = {Defining Linkages between the GSC and NSF{\textquoteright}s LTER Program: How the Ecological Metadata Language (EML) Relates to GCDML and Other Outcomes.},
journal = {Omics},
volume = {12},
year = {2008},
pages = {151-156},
keywords = {AND, GCE, LNO, NTL, PIE, SBC},
doi = {10.1089/omi.2008.0015},
author = {San Gil, Inigo. and Pan, J.Y and Palanisamy, G. and Henshaw, D. and OBrien, M. and Kinkel, L. and McMahon, K. and Kottman, R. and Amaral-Zettler, L. and Hobbie, J. and Goldstein, P. and Sheldon, W. and Guralnick, R.P. and Brunt, J. W. and Michener, W. K. and Schmidt, T. and Servilaa, M. and Aguilar, R. and Gries, C. and Gray, T. and Field, D. and Cole, J.}
@article {66770,
title = {The Dynamics of Top-down and Bottom-up control in New England salt marshes},
journal = {Oikos},
volume = {117},
year = {2008},
pages = {1050-1056},
abstract = {Traditionally, salt marsh ecosystems were thought to be controlled exclusively by bottom},
keywords = {ecology, GCE, salt marsh},
doi = {10.1111/j.0030-1299.2008.16296.x},
author = {Sala, N. and Bertness, Mark D. and Silliman, Brian R.}
@article {66792,
title = {The effect of secondary circulation on the salt distribution in a sinuous coastal plain estuary: Satilla River, GA, USA},
journal = {Continental Shelf Research},
volume = {29},
year = {2008},
pages = {15-28},
abstract = {An analysis of observational data suggests salt exchange in a sinuous coastal plain estuary is significantly impacted by counter-rotating residual horizontal eddies formed by channel curvature in meandering channels. The parts of adjacent eddies that advect material downstream follow the deep part of the channel where the flow continually criss-crosses from one side of the channel to the other and follows a relatively unimpeded trajectory to the sea. On the other hand, the parts of adjacent eddies that advect material upstream cross the channel at a different location where it encounters a series of shoals. In this case, the resulting upstream transport of salt is relatively inefficient and retards the rate at which salt can disperse upstream into the estuary. The strength of these circulations is modulated by the spring/neap cycle, allowing for a stronger gravitational mode of exchange to develop near neap tides, but has minimal impact on the length of the salt intrusion. It is suggested that the impeded upstream salt transport accounts for the observation that an impulse of river discharge advects a given isohaline 10 km downstream in 20 days, but that after the impulse, 70 days are required to return the isohaline to a similar position, counter to the notion of a simple dependence of intrusion length on river discharge.},
keywords = {channel meanders, GCE, salt exchange, secondary circulation, stratification},
doi = {10.1016/j.csr.2008.03.018},
author = {Seim, Harvey E. and Blanton, Jackson O. and Elston, Susan A.}
@article {66858,
title = {Exploring marine bacterial diversity in coastal Georgia salt marshes using DNA technology},
journal = {The American Biology Teacher},
volume = {70},
year = {2008},
pages = {279-283},
abstract = {An important aspect of teaching biology is to expose students to the concept of biodiversity. For this purpose, bacteria are excellent examples. Prokaryotes were the first inhabitants on Earth, surviving and even thriving under very harsh conditions as new species continuously evolved. In fact, it is believed that there are more than 5 x 10^30 prokaryotes living on Earth today (Whitman et al., 1998). Our current knowledge of these tiny organisms is very limited, and less than 1\% of all bacterial species have been described (Horner-Devine et al., 2004). However, the prominent roles bacteria play in nature are not easy to overlook: Their functions range from providing essential nutrients to plants through nitrogen-fixation (such as for Rhizobium leguminosarum) to enhancement of nutrient absorption in animal intestines (such as for Escherichia coli). As a result, identifying unknown species of bacteria and extending our understanding of known ones are important tasks for 21st Century scientists.},
keywords = {bacteria, diversity, dna, education, GCE, microbial ecology, molecular biology, salt marshes},
author = {Dong, Yihe. and Guerrero, Stella. and Moran, Mary Ann.}
@article {66903,
title = {Grasshopper (Orthoptera: Tettigoniidae) species composition and size across latitude in Atlantic Coast salt marshes},
journal = {Estuaries and Coasts},
volume = {31},
year = {2008},
pages = {335-343},
abstract = {Although grasshoppers are common salt marsh herbivores, we know little about geographic variation in their species composition. We documented latitudinal variation in species composition of the tettigoniid grasshopper fauna of Atlantic Coast salt marshes. Tettigoniids (N=740 adults) were collected from the Spartina alterniflora zone of 31 salt marsh sites across a latitudinal range of 13.19},
keywords = {atlantic coast, GCE, grasshopper, invertebrate, latitude, orthoptera, salt marsh, tettigoniidae},
author = {Wason, Elizabeth L. and Pennings, Steven C.}
@article {66916,
title = {Heat budget for a shallow, sinuous salt marsh estuary},
journal = {Continental Shelf Research},
volume = {28},
year = {2008},
pages = {1740},
abstract = {An experimental study of temperature cycles and the heat budget in the Duplin River, a tidal creek bordered by extensive intertidal salt marshes, was carried out in late summer of 2003 and spring of 2004 near Sapelo Island on the central Georgia coast in the southeastern US. Three water masses are identified with differing temperature and salinity regimes, the characteristics of which are dictated by channel morphology, tidal communication with the neighboring sound, ground water hydrology, the extent of local intertidal salt marshes and side channels and the spring},
keywords = {duplin river, GCE, georgia us, heat budget, salt marsh estuary, sapelo island, tidal mixing},
doi = {10.1016/j.csr.2008.04.008},
author = {McKay, Paul. and Di Iorio, Daniela.}
@article {66943,
title = {Impact of fertilization on a salt marsh food web in Georgia},
journal = {Estuaries and Coasts},
volume = {31},
year = {2008},
pages = {313-325},
abstract = {We examined the response of a salt marsh food web to increases in nutrients at 19 coastal sites in Georgia. Fertilization increased the nitrogen content of the two dominant plants, Spartina alterniflora and Juncus roemerianus, indicating that added nutrients were available to and taken up by both species. Fertilization increased Spartina cover, height and biomass and Juncus height, but led to decreases in Juncus cover and biomass. Fertilization increased abundances of herbivores (grasshoppers) and herbivore damage, but had little effect on decomposers (fungi), and no effect on detritivores (snails). In the laboratory, herbivores and detritivores did not show a feeding preference for fertilized versus control plants of either species, nor did detritivores grow more rapidly on fertilized versus control plants, suggesting that changes in herbivore abundance in the field were driven more by plant size or appearance than by plant nutritional quality. Community patterns in control plots varied predictably among sites (i.e. 17 of 20 regression models examining variation in biological variables across sites were significant), but variation in the effects of fertilization across sites could not be easily predicted (i.e. only 6 of 20 models were significant). Natural variation among sites was typically similar or greater than impacts of fertilization when both were assessed using the coefficient of variation. Overall, these results suggest that eutrophication of salt marshes is likely to have stronger impacts on plants and herbivores than on decomposers and detritivores, and that impacts at any particular site might be hard to distinguish from natural variation among sites.},
keywords = {ecology, fertilization, food webs, GCE, marsh, nutrients, plant},
author = {McFarlin, Caroline R. and Brewer, J. S. and Buck, Tracy L. and Pennings, Steven C.}
@article {67016,
title = {Like herbivores, parasitic plants are limited by host nitrogen content},
journal = {Plant Ecology},
volume = {196},
year = {2008},
pages = {245-250},
abstract = {Herbivores generally benefit from increased plant nitrogen content, because the nitrogen content of animals is much higher than that of plants. Consequently, high plant nitrogen alleviates the profound stoichiometric imbalance that herbivores face in their diets. Parasitic plants provide the opportunity to test this generalization for consumers across kingdoms. We fertilized two microhabitats in a California salt marsh that were dominated by Salicornia virginica or a mixture of S. virginica and Jaumea carnosa. The nitrogen content of both host plants and of the holoparasite Cuscuta salina (dodder) increased in fertilized plots in both microhabitats. Cuscuta preferred to attack Jaumea, although Jaumea had lower nitrogen content than Salicornia. When host nitrogen content was altered by fertilizing plots, however, the percent cover of the parasite doubled. Although parasitic plants and their hosts have similar tissue nitrogen contents, suggesting no stoichiometric imbalance between host and consumer, parasitic plants do not feed on host tissue, but on host xylem and phloem, which are very low in nitrogen. Consequently, parasitic plants face the same dietary stoichiometric constraints as do herbivores, and both herbivores and holoparasitic plants may respond positively to increases in host nitrogen status.},
keywords = {cuscuta, fertilization, GCE, nitrogen, nutrients, parasitic plant},
doi = {10.1007/s11258-007-9348-z},
url = {http://www.springerlink.com/content/8120554604018231/},
author = {Pennings, Steven C. and Simpson, Juliet C.}
@inbook {67101,
title = {Nitrogen Cycling in Estuarine and Nearshore Sediments},
booktitle = {Nitrogen in the Marine Environment, Second Edition},
year = {2008},
pages = {867-915},
publisher = {Elsevier Inc.},
organization = {Elsevier Inc.},
keywords = {biogeochemistry, estuary, GCE, nearshore, nitrogen, nutrient cycling, nutrient dynamics},
doi = {10.1016/B978-0-12-372522-6.00019-0},
url = {http://dx.doi.org/10.1016/B978-0-12-372522-6.00019-0},
author = {Joye, Samantha B. and Anderson, Iris.},
editor = {Carpenter, Edward J.}
@article {67115,
title = {A numerical study of tidal asymmetry in Okatee Creek, South Carolina},
journal = {Estuarine Coastal and Shelf Science},
volume = {78},
year = {2008},
pages = {190-202},
abstract = {The Okatee River, South Carolina is characterized by a narrow tidal channel and an extensive area of intertidal salt marshes. Current mea- surements in the upstream portion Okatee Creek show that tidal flow features an asymmetric pattern: ebb current is stronger than flood current. The ebb dominance is mainly caused by deformation of the dominant astronomical tidal constituent M2. An unstructured grid, finite volume coastal ocean model (FVCOM) with wet-dry point treatment method is applied to examine physical mechanisms of M4 overtide generation. Modelexperimentsshowthatmeanabsoluteamplitudeandphaseerrorsare3.1cmand1.7\&$\#$1113089; forM2elevation,2.4cms\&$\#$1113090;1and0.8\&$\#$1113089; forM2current major axis, 2.1 cm and 1.8\&$\#$1113089; for M4 elevation, and 2.1 cm s\&$\#$1113090;1 and 24.6\&$\#$1113089; for M4 current major axis. The overall pattern of tidal asymmetry is qualitatively reproduced. Various sensitivity experiments suggest that the generation of M4 overtide is a result of nonlinear interaction of tidal currents with irregular creek geometry and bottom topography. Consistent with the classical view, the large volume of intertidal water storage is the major reason for ebb dominance in the creek. However, the zero-inertia assumption (i.e., negligible advective terms) is probably not valid for the entire tidal cycle. Besides the pressure gradient force and the bottom friction force, terms related to lateral shear of the along-estuary velocity (i.e., advective inertia and horizontal eddy viscosity) may also contribute in horizontal momentum balance. Exclusion of the flooding-draining processes over the intertidal zone will severely underestimate tidal currents in the river channel and make the tidal asymmetry less prominent. Published by Elsevier Ltd.},
keywords = {ebb dominance, fvcom, GCE, intertidal salt marsh, numerical simulation, okatee creek, tidal asymmetry},
doi = {10.1016/j.ecss.2007.11.027},
url = {http://dx.doi.org/10.1016/j.ecss.2007.11.027},
author = {Huang, H. and Chen, C. and Blanton, Jackson O. and Andrade, Francisco.}
@article {67117,
title = {Nutrient replete benthic microalgae as a source of labile dissolved organic carbon to coastal waters},
journal = {Estuaries and Coasts},
volume = {31},
year = {2008},
pages = {860-876},
abstract = {Dissolved organic carbon (DOC) flux dynamics were examined in the context of other biogeochemical cycles in intertidal sediments inhabited by benthic microalgae. In August 2003, gross oxygenic photosynthetic (GOP) rates, oxygen penetration depths, and benthic flux rates were quantified at seven sites along the Duplin River, GA, USA. Sediments contained abundant benthic microalgal (BMA) biomass with a maximum chlorophyll a concentration of 201 mg chl a m-2. Oxygen microelectrodes were used to determine GOP rates and O2 penetration depth, which were tightly correlated with light intensity. Baseline and 15N-nitrate amended benthic flux core incubations were employed to quantify benthic fluxes and to investigate the impact of BMA on sediment water exchange under nitrogen (N)-limited and N-replete conditions. Unamended sediments exhibited tight coupling between GOP and respiration and served as a sink for water column dissolved inorganic nitrogen (DIN) and a source of silicate and dissolved inorganic carbon (DIC). The BMA response to the N addition indicated sequential nutrient limitation, with N limitation followed by silicate limitation. In diel (light},
keywords = {benthic, biogeochemistry, DOC, GCE, microalgae, nutrients, organic carbon},
doi = {10.1007/s12237-008-9077-0},
url = {http://www.springerlink.com/content/j6531n2472m364u4/?p=4887a9488d8a46098b68a028eafc3b71\&pi=0},
author = {Porubsky, William P. and Velasquez, Liliana E. and Joye, Samantha B.}
@article {67138,
title = {Patterns of plant diversity in Georgia and Texas salt marshes},
journal = {Estuaries and Coasts},
volume = {31},
year = {2008},
pages = {673-681},
abstract = {A fundamental question in ecology is how biological interactions and biogeographic processes interact to determine the biodiversity of local sites. We quantified patterns of plant species diversity on transects across elevation at 59 salt marsh sites in Georgia and 49 sites in Texas. Although these regions have similar climates and floras, we anticipated that diversity might differ because of differences in tidal regime. Diversity was measured at global, regional, site, and plot scales to consider processes occurring at all levels. Species pools were similar between regions. Texas had greater diversity at the site and plot scales, suggesting that processes occurring at the site scale differed. The greater diversity of Texas sites and plots was associated with wider distributions of individual species across the marsh landscape, and proportionally more middle marsh (a high diversity zone) and less low marsh (a low diversity zone) than in Georgia marshes. Preliminary data suggested that these differences were not due to differences in salinity regime or standing biomass between regions, leaving differences in tidal regime as the most plausible hypothesis accounting for differences in plant diversity. We speculate that the less-predictable tidal regime in Texas leads to temporal variation in abiotic conditions that limit the ability of any one species to competitively exclude others from particular marsh zones.},
keywords = {diversity, ecology, GCE, georgia, plant, populations, salt marsh, texas},
author = {Kunza, Amy E. and Pennings, Steven C.}
@mastersthesis {67161,
title = {Plant-herbivore interactions in U.S. Atlantic Coast salt marshes: the effect of omnivory and geographic location},
year = {2008},
pages = {116},
school = {University of Houston},
address = {Houston, TX},
abstract = {Plant-herbivore interactions are common and have been the focus of muchresearch. Ecologists have realized that in order to better understand the generality ofplant-herbivore interactions, there is a need to study factors that mediate theseinteractions. Here, I first address whether plant-herbivore interactions are affected byomnivores, second test whether latitudinal variation in plant quality might explainvariation in herbivore body size, and finally examine whether geographic origin of plants and herbivores affects herbivore performance.First, I examined the top-down impacts of an omnivorous crab, Armasescinereum, on the shrub Iva frutescens and its arthropod fauna. My hypothesis was that Armases would benefit Iva through a trophic cascade, and that this benefit would be stronger than the direct negative effect of Armases on Iva. Field and laboratory experiments both supported this hypothesis. Although Armases is an omnivore, it produced strong top-down forces and a trophic cascade because it fed preferentially on herbivores rather than plants when both were available. Second, I tested the hypothesis that latitudinal variation in plant quality might help explain Bergmann},
keywords = {aphid, beetle, crab, GCE, grasshopper, herbivory, insect, latitude, salt marsh, secondary production, top-down bottom-up},
author = {Ho, Chuan-Kai.}
@article {67181,
title = {Protistan bacterivory and benthic microbial biomass in an intertidal creek mudflat},
journal = {Marine Ecology Progress Series},
volume = {361},
year = {2008},
pages = {59-68},
abstract = {We examined 8 sediment samples collected at 3 h intervals at Dean Creek (Sapelo Island, Georgia) to assess the impact of protist bacterivory on the standing crops of benthic bacterial biomass. The combined biomass of the benthic microalgae (BMA), bacteria, heterotrophic protists, and meiofauna ranged from 0.41 to 0.57 mg C g^},
keywords = {benthic food web, ciliates, GCE, meiofauna, microphytobenthos, microzoobenthos, protozoa, salt marsh, sapelo island, tidal creeks},
doi = {10.3354/meps07422},
url = {http://dx.doi.org/10.3354/meps07422},
author = {First, Matthew R. and Hollibaugh, James T.}
@article {67190,
title = {Rank clocks and plant community dynamics},
journal = {Ecology},
volume = {89},
year = {2008},
pages = {3534-3541},
abstract = {Summarizing complex temporal dynamics in communities is difficult to achieve in a way that yields an intuitive picture of change. Rank clocks and rank abundance statistics provide a graphical and analytical framework for displaying and quantifying community dynamics. We used rank clocks, in which the rank order abundance for each species is plotted over time in temporal clockwise direction, to display temporal changes in species abundances and richness. We used mean rank shift and proportional species persistence to quantify changes in community structure in long-term data sets from fertilized and control plots in a late successional old field, frequently and infrequently burned tallgrass prairie, and Chihuahuan desert grassland and shrubland communities. Rank clocks showed that relatively constant species richness masks considerable temporal dynamics in relative species abundances. In the old field, fertilized plots initially experienced high mean rank shifts that stabilized rapidly below that of unfertilized plots. Rank shifts were higher in infrequently burned vs. annually burned tallgrass prairie and in desert grassland compared to shrubland vegetation. Proportional persistence showed that arid grasslands were more dynamic than mesic grasslands. We conclude that rank clocks and rank abundance statistics provide important insights into community dynamics that are often hidden by traditional univariate approaches.},
keywords = {CDR, community, dynamics, ecology, GCE, plant, rank clocks, SEV},
doi = {10.1890/07-1646.1},
url = {http://www.esajournals.org/doi/abs/10.1890/07-1646.1},
author = {Collins, S. L. and Clark, Christopher M. and Suding, K.N. and Cleland, Elsa E and Batty, M. and Pennings, Steven C. and Gross, Katherine L. and Grace, James B. and Gough, Laura. and Fargione, J. E.}
@inbook {67220,
title = {Restoration of coastal zones},
booktitle = {Ecologicial Engineering},
year = {2008},
pages = {637-644},
publisher = {Elsevier B.V.},
organization = {Elsevier B.V.},
edition = {1st},
address = {Oxford},
keywords = {coastal dunes, ecology, engineering, GCE, restoration, tidal marsh},
author = {Craft, Christopher B. and Bertram, Jillian. and Broome, S. W.},
editor = {Fath, B. D.}
@article {67229,
title = {Salt marsh dieback: An overview of recent events in the US.},
journal = {Estuarine, Coastal and Shelf Science},
volume = {80},
year = {2008},
pages = {1-11},
abstract = {This paper provides an overview of the marsh dieback events that have been observed along the east and gulf coasts of the U.S. over the past decade. It is likely that some of the recently reported changes in marsh vegetation were affected by physical or biotic disturbances that are known to generate bare areas, such as overgrazing or wrack smothering. Other areas may be experiencing a state change such as that caused by long-term changes in sea level. However, sites in many areas are not readily explained by these causes and are considered to have experienced},
keywords = {dieback, drought, GCE, gulf coast, mid-atlantic, northeast, salt marsh, southeast, spartina, USA},
doi = {10.1016/j.ecss.2008.08.009},
author = {Alber, Merryl. and Swenson, Erick M. and Adamowicz, Susan C. and Mendelssohn, Irving A.}
@article {67294,
title = {Species responses to nitrogen fertilization in herbaceous plant communities, and associated species traits},
journal = {Ecology},
volume = {89},
year = {2008},
pages = {1175},
abstract = {This synthetic dataset contains plant species relative abundance measures from 35 nitrogen (N) fertilization experiments conducted at 10 sites across North America. The dataset encompasses the fertilization responses of 691 species from 1,159 experimental plots. The methodology varied among experiments, in particular with regards to the type and amount of N added, plot size, species composition measure (biomass harvest, pin count or percent cover), additional experimental manipulations, and experimental duration. At each site, each species has been classified according to a number of easily identified categorical functional traits, including life history, life form, the number of cotyledons, height relative to the canopy, potential for clonal growth, and nativity to the United States. Additional data are available for many sites, indicated by references to publications and websites. Analyses of these data have shown that N enrichment significantly alters community composition in ways that are predictable on the basis of plant functional traits as well as environmental context. This dataset could be used to answer a variety of questions about how plant community composition and structure respond to environmental changes.},
keywords = {ARC, community, ecology, fertization, GCE, plant, SEV, SGS, species traits},
author = {Cleland, Elsa E and Burke, Indie C. and Lauenroth, G. P. and Robertson, J. C. and Simpson, Juliet C. and Tilman, D. and Suding, K.N. and Clark, Christopher M. and Collins, S. L. and Fargione, J. E. and Gough, Laura. and Gross, Katherine L. and Milchunas, DG. and Pennings, Steven C. and Bowman, W. D.}
@article {67314,
title = {A study of estuarine flow using the roving adcp data},
journal = {Ocean Science Journal},
volume = {43},
year = {2008},
pages = {81-90},
abstract = {A study of estuarine flows during a neap tide was performed using 13-hour roving acoustic Doppler current profiles (ADCP) and conductivity-temperature-depth (CTD) profiles in the Altamaha River estuary, Georgia, U.S.A. The least-squared harmonic analysis method was used to fit the tidal (M2) component and separate the flow into two components: the tidal and residual (M2-removed) flows. We applied this method to depth-averaged data. Results show that the M2 component demonstrates over 95\% of the variability of observation data. As the flow was dominated by the M2 tidal component in a narrow channel, the tidal ellipse distribution was essentially a back-and-forth motion. The amplitude of M2 velocity component increased slightly from the river mouth (0.45 m/sec) to land (0.6 m/sec) and the phase showed fairly constant values in the center of the channel and rapidly decreasing values near the northern and southern shoaling areas. The residual flow and transport calculated from depth-averaged flow shows temporal variability over the tidal time scale. Strong landward flows appeared during slack waters which may be attributed to increased baroclinic forcing when turbulent mixing decreases.},
keywords = {adcp, current, estuary, flow, GCE},
doi = {10.1007/BF03020584},
url = {http://www.springerlink.com/content/mn37822204u01566/},
author = {Kang, KiRyong. and Di Iorio, Daniela.}
@mastersthesis {67326,
title = {Temporal and Spatial Variability of Transport and Mixing Mechanisms: Using Heat and Salt in the Duplin River, Georgia},
year = {2008},
pages = {217},
school = {University of Georgia},
address = {Athens GA},
abstract = {A study of the Duplin River, a shallow, sinuous, tidal creek which connects the salt marshes of Sapelo Island, on the central Georgia coast, with the waters of Doboy Sound and the coastal Atlantic Ocean, was conducted to quantify the physical processes which regulate the flux and zonation of heat and salt throughout the creek system.Three water masses are identified with differing temperature and salinity regimes. Hourly scale heat budgets are constructed for the upper (warmer) and lower (cooler) areas of the Duplin River showing the diminishing importance of tidal advection away from the mouth of the creek along with the concomitant increase in the importance of both direct atmospheric fluxes and of interactions with the marsh and side creeks. The heat budget is re-examined on daily averaged scales revealing the decreased importance of advective fluxes relative to direct atmospheric fluxes on this scale but the constant importance of marsh/creek interactions regardless of time scale or season. Tidally averaged along channel salt fluxes are calculated and a contrast is drawn between the lower and the upper Duplin. The main channel of the lower Duplin is bordered by creekless marsh, marsh hammocks and hard upland and salt fluxes are largely constrained to the main channel with salinity in the lower Duplin closely tracking observed salt fluxes. The upper Duplin is isolated from the lower Duplin by a sinuous channel and is subject to significant local fresh groundwater input. The upper Duplin acts as a reversing estuary on a fortnightly time scale. Salt fluxes are not constrained to the main channel but show a significant influence of the marsh. Vertical mixing is shown to be modulated on both M4 and fortnightly frequencies with turbulent stresses being generated near the bed and propagating into the water column on periods of max flood and ebb and being significantly greater on spring tide than on neap. Horizontal mixing is driven by tidal dispersion, which is modulated by the fortnightly spring/neap cycle. Net export of salt from the lower Duplin is shown to be due to residual advection modified by upstream tidal pumping which, in the absence of external forcing, exhibits a pulsating character with net export taking place for a short period on spring tide followed by a longer period of net import of salt.A box model is developed to explore subtidal inputs of groundwater and salt into the three water masses of the Duplin River. The results of this model are examined to draw insights into the magnitude and spatial distribution of these processes and their effect on the Duplin River water masses.},
keywords = {box model, dispersion, duplin river, estuary, GCE, georgia, groundwater, heat budget, marsh-creek interaction, reversing estuary, salt flux, salt marsh, sapelo island, tidal creek, tidal pumping, u.s, vertical mixing},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/GCEPub453_Mckay_PhD_2008.pdf},
author = {McKay, Paul.}
@article {67357,
title = {Understanding and forecasting the effects of sea level rise and intense windstorms on coastal and upland ecosystems: the need for a continental-scale network of observatories},
journal = {Frontiers in Ecology},
volume = {6},
year = {2008},
pages = {255-263},
abstract = {We identify a continental-scale network of sites to evaluate how two aspects of climate change},
keywords = {climate, coastal, forecasting, GCE, meteorology, Network, observatories, PIE, sea level, upland, windstorms},
doi = {10.1890/070153},
author = {Hopkinson, Charles S. and Lugo, Ariel. and Alber, Merryl. and Covich, Alan. and Van Bloem, S. J.}
@article {67378,
title = {Variation in Prokaryotic Community Composition as a Function of Resource Availability in Tidal Creek Sediments},
journal = {Applied and Environmental Microbiology},
volume = {74},
year = {2008},
pages = {1836-1844},
abstract = {n anaerobic coastal sediments, hydrolytic and/or fermentative bacteria degrade polymeric material and produce labile intermediates, which are used by terminal metabolizers to complete the conversion of organic material to CO2. We used molecular approaches to evaluate the response of two bacterial terminal metabolizer groups from a coastal tidal creek sediments, sulfate reducers and methanogens, to controlled changes in carbon resource supply. Tidal creek sediment bioreactors were established in April and August 2004. For each date, intact sediment sections were continuously supplied with flowthrough seawater that was either unamended or amended with the high-molecular-weight polysaccharide dextran. Biogeochemical data indicate that the activity of fermenting bacteria and the terminal metabolizers was limited by organic carbon supply during both experiments, with a significant increase in net volatile fatty acid (VFA) production and rates of sulfate reduction and methanogenesis following dextran addition. Community composition (measured by using terminal restriction fragment length polymorphism analysis, and functional gene [dsrA, mcrA] clone libraries) changed from April to August. However, community composition was not different between amended and unamended cores within each month, despite the change in resource level. Moreover, there was no relationship between community richness and evenness with resource level. This lack of variation in community composition with C addition could be attributed to the dynamic environment these sediment communities experience in situ. Fluctuations in VFA concentrations are most likely very high, so that the dominant bacterial species must be able to outcompete other species at both high and low resource levels.},
keywords = {community, GCE, microbiology, nutrients, sediment, tidal creek},
doi = {10.1128/AEM.00854-07},
url = {http://aem.asm.org/cgi/content/abstract/74/6/1836},
author = {Edmonds, Jennifer W. and Weston, Nathaniel B. and Joye, Samantha B. and Moran, Mary Ann.}
@article {67408,
title = {Ammonia oxidation and ammonia-oxidizing Bacteria and Archaea populations from estuaries with differing histories of hypoxia},
journal = {ISME Journal},
volume = {1},
year = {2007},
pages = {660-662},
abstract = {Nitrification, the oxidation of NH4+ to NO2- and subsequently to NO3-, plays a central role in the nitrogen cycle and is often a critical first step in nitrogen removal from estuarine and coastal environments. The first and rate limiting step in nitrification is catalyzed by the enzyme ammonia monooxygenase (AmoA). We evaluate the relationships between the abundance of ammonia oxidizing archaea (AOA) and ammonia oxidizing bacteria (AOB) amoA genes; potential nitrification rates; and environmental variables to identify factors influencing AOA abundance and nitrifier activity in estuarine sediments. Our results showed that potential nitrification rates increased as abundance of AOA amoA increased. In contrast, there was no relationship between potential nitrification rates and AOB amoA abundance. This suggests that AOA are significant in estuarine nitrogen cycling. Surprisingly, more of the variability in potential nitrification rates was predicted by salinity and pore water sulfide than by dissolved oxygen history.},
keywords = {ammonia, ammonia_oxidation, aoa, aob, crenarchaea, GCE, hypoxia, nitrification},
doi = {10.1038/ismej.2007.79},
author = {Caffrey, Jane M. and Bano, Nasreen. and Kalanetra, Karen. and Hollibaugh, James T.}
@article {67433,
title = {Bacterioplankton assemblages transforming dissolved organic compounds in coastal seawater},
journal = {Environmental Microbiology},
volume = {9},
year = {2007},
pages = {2025-2037},
abstract = {To characterize bacterioplankton functional assemblages that transform specific components of the coastal seawater dissolved organic carbon (DOC) pool, bromodeoxyuridine (BrdU) was used to label the bacterioplankton cells that were active following addition of single-DOC model compounds: two organic osmolytes [dimethylsulfoniopropionate (DMSP) and glycine betaine (GlyB)] and two aromatic monomers [para-hydroxybenzoic acid (pHBA) and vanillic acid (VanA)]. Bacterial populations were analysed based on in situ fluorescent immunodetection of BrdU incorporation followed by fluorescence-activated cell sorting (FACS). Sorted cells were then characterized by 16S rDNA-based analysis. Populations with high BrdU incorporation level (HI) developed within 8 h of introduction of 100 nM model compound. Terminal restriction fragment length polymorphisms (T-RFLP) analysis indicated that the HI populations in all four amendments were composed of bacteria from the same major taxa (phylum and subphylum levels), but the relative abundance of each differed. High-resolution clone libraries (each containing ~200 clones) showed that the HI populations in the GlyB and VanA amendments consisted of both metabolic generalists and specialists within the l-Proteobacteria (mainly members of the Roseobacter clade),},
keywords = {bacteria, bacterioplankton, DOC, GCE, microbial ecology, organic carbon, transformation},
doi = {10.1111/j.1462-2920.2007.01318},
author = {Mou, Xiaozhen. and Hodson, Robert E. and Moran, Mary Ann.}
@mastersthesis {67528,
title = {Determination of gas exchange velocities based on measurements of air-sea CO2 partial pressure gradients and direct chamber fluxes in the Duplin River, Sapelo Island, GA},
year = {2007},
pages = {84},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {CO2 fluxes were determined directly, using a floating chamber for ten to fifteen minute intervals over the winter between 2006 and 2007 from Marsh Landing Dock on Sapleo Island, Georgia. Air-Sea pCO2 differences were measured alongside the fluxes using a coupled equilibrator and infrared gas detector whereby gas transfer velocities (k) were calculated. In addition, current speeds were measured using an acoustic doppler current profiler and correlated with gas transfer velocities along side wind speeds. In the Duplin River, with the exception of spring tides, wind is an important variable controlling k in agreement with prior empirical measurement of estuarine k values. However, bottom generated turbulence was responsible for more than half of the magnitude of measured gas transfer velocities for 17 out of 100 of the deployments. In addition, gas transfer velocities during spring tides may be able to substantially increase k, however independent verification with an un-tethered floating chamber is needed to verify this in the Duplin River.},
keywords = {carbon dioxide, CO2, duplin river, flux, gas, GCE, pressure},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/Justin_Hartman_MS_Thesis_2007.pdf},
author = {Hartmann, Justin.}
@article {67609,
title = {Environmental and plant community determinants of species loss following nitrogen enrichment},
journal = {Ecology Letters},
volume = {10},
year = {2007},
pages = {596-607},
abstract = {Global energy use and food production have increased nitrogen inputs to ecosystems worldwide, impacting plant community diversity, composition, and function. Previous studies show considerable variation across terrestrial herbaceous ecosystems in the magnitude of species loss following nitrogen (N) enrichment. What controls this variation remains unknown. We present results from 23 N-addition experiments across North America, representing a range of climatic, soil and plant community properties, to determine conditions that lead to greater diversity decline. Species loss in these communities ranged from 0 to 65\% of control richness. Using hierarchical structural equation modelling, we found greater species loss in communities with a lower soil cation exchange capacity, colder regional temperature, and larger production increase following N addition, independent of initial species richness, plant productivity, and the relative abundance of most plant functional groups. Our results indicate sensitivity to N addition is co-determined by environmental conditions and production responsiveness, which overwhelm the effects of initial community structure and composition.},
keywords = {CDR, community, ecology, enrichment, fertilization, GCE, nitrogen, nutrients, plant, species loss},
doi = {10.1111/j.1461-0248.2007.01053.},
author = {Clark, Christopher M. and Cleland, Elsa E and Collins, S. L. and Fargione, J. E. and Gough, Laura. and Gross, Katherine L. and Pennings, Steven C. and Suding, K.N. and Grace, James B.}
@article {67656,
title = {Freshwater input structures soil properties, vertical accretion, and nutrient accumulation of Georgia and U.S. tidal marshes},
journal = {Limnology \& Oceanography},
volume = {52},
year = {2007},
pages = {1220-1230},
abstract = {To identify relationships between freshwater input and marsh soil properties, measurements of bulk density, nutrients (carbon [C], nitrogen [N], phosphorus [P]), accretion, and accumulation were compared in tidal marshes of three estuaries of Georgia that varied in delivery of freshwater. Soil organic C and N (0-30 cm) were two times greater in marshes of the freshwater-dominated Altamaha River than in the salt marshes of Doboy Sound and Sapelo River. 137Cs accretion and accumulation of organic C and N were three to five times greater in freshwater-dominated marshes than in salt marshes. The patterns observed in Georgia marshes were geographically general; data for tidal freshwater and brackish marsh soils compiled from 61 studies in the conterminous United States showed lower bulk density and higher percent organic C and N than salt marshes, regardless of geographic region. Salinity, a proxy for freshwater input, was inversely correlated with percent soil organic C and N and with vertical accretion in Georgia marshes and in marshes elsewhere in the conterminous United States. There was no relationship between above- or belowground emergent plant production and salinity of Georgia marshes but the rate of root decomposition was positively related to salinity, and decomposition rate was negatively related to percent soil organic C and C accumulation. In Georgia tidal marshes and elsewhere, soil organic matter content and accumulation are mediated by freshwater through its effects on decomposition.},
keywords = {freshwater, GCE, input structures, marsh, nutrient accumulation, soil, tidal, vertical accretion},
author = {Craft, Christopher B.}
@inbook {67727,
title = {Integrating hydrologic and geophysical data to constrain coastal surficial aquifer processes at multiple spatial and temporal scales},
booktitle = {Subsurface Hydrology: Data Integration for Properties and Processes},
volume = {171},
year = {2007},
pages = {161-182},
publisher = {American Geophysical Union Geophysical Monograph, Series Volume 171},
organization = {American Geophysical Union Geophysical Monograph, Series Volume 171},
abstract = {Since 1997, repeated, coincident geophysical surveys and extensive hydrologic studies in shallow monitoring wells have been used to study static and dynamic processes associated with surface water-groundwater interaction at a range of spatial scales at the estuarine and ocean boundaries of an undeveloped, permeable barrier island in the Georgia part of the U.S. South Atlantic Bight. Because geophysical and hydrologic data measure different parameters, at different resolution and precision, and over vastly different spatial scales, reconciling the coincident data or even combining complementary data sets has required a range of approaches. This study uses geophysical imaging and inversion, hydrogeochemical analyses and well-},
keywords = {coastal, GCE, geophysical, hydrologic, spatial scale, surficial aquifer, temporal scale},
doi = {10.1029/171GM13},
author = {Schultz, Gregory M. and Ruppel, Carolyn D. and Fulton, Patrick.},
editor = {Singha, K.}
@article {67767,
title = {Latitudinal variation in plant-herbivore interactions in European salt marshes},
journal = {Oikos},
volume = {116},
year = {2007},
pages = {543:549},
abstract = {Ecological interactions often vary geographically. Work in salt marshes on the Atlantic Coast of the United States has documented community-wide latitudinal gradients in plant palatability and plant traits that may be driven in part by greater herbivore pressure at low latitudes. To determine if similar patterns exist elsewhere, we studied six taxa of saltmarsh plants ( Atriplex, Juncus, Limonium, Salicornia, Spartina and Suaeda) at European sites at high (Germany and the Netherlands) and low (Portugal and Spain) latitudes. We conducted feeding assays using both native and non-native consumers, and documented patterns of herbivore damage in the field. As in the United States, high-latitude plants tended to be more palatable than low-latitude plants when offered to consumers in paired feeding assays in the laboratory, although assays with grasshopper consumers were less consistent than those with crab consumers, and plants in the field at low-latitude sites tended to experience greater levels of herbivore pressure than plants at high-latitude sites. Similarly, high-latitude leaf litter was more palatable than litter from low-latitude plants when offered to consumers in paired feeding assays in the laboratory. Latitudinal gradients in plant palatability and herbivore pressure may be a general phenomenon, and may contribute to latitudinal gradients in decomposition processes.},
keywords = {european, GCE, interactions, latitude, plant-herbivore, plants, salt marsh},
author = {Pennings, Steven C. and Pfauder, Anett. and Salgado, Cristiano S. and Zimmer, Martin. and Dias, Natalia. and Sprung, Martin. and Dav and Ho, Chuan-Kai. and Kunza, Amy E. and McFarlin, Caroline R. and Mews, Malte.}
@mastersthesis {67817,
title = {Molecular description of ascomycete fungal communities on Spartina spp. in the U.S.},
year = {2007},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {Ascomycetous fungi play a crucial role in the decomposition of salt marsh vegetation. The first part of this research used molecular methods to examine whether physical associations exist between individual bacterial and common ascomycetous fungal species that co-occur on decaying smooth cordgrass, Spartina alterniflora, in a southeastern U.S. salt marsh. We found that bacterial communities were unaffected by the identity of initial fungal decomposers, suggesting that few species-specific associations exist between those members of the Spartina decomposer community. The next part of the study involved a characterization of ascomycetes involved in the decomposition of different species of Spartina in different environments. In California, the fungi associated with S. alterniflora, S. foliosa, the hybrid between them, and S. densiflora were all characterized using terminal restriction fragment length polymorphism (T-RFLP) analysis of their internal transcribed spacer (ITS) region of rRNA genes as well as clone libraries. Although we found no effect from the hybridization of two host species, we did see significant differences in the fungal decomposer communities both within and among species. S. densiflora hosted several unique ascomycetes. Two previously described ascomycetes, Phaeosphaeria spartinicola and Mycosphaerella, were ubiquitous on all samples analyzed. On the east coast, ascomycete communities on samples of S. alterniflora and S. patens collected in four states (Georgia, North Carolina, New York, and Massachusetts) were compared, again using T-RFLP analysis of the interspacer region. Results show that diversity of the ascomycete taxa on S. patens hosts a higher number of unique ascomycete species than S. alterniflora, and that it has significantly higher diversity, but there were no consistent differences among states. P. spartinicola and Mycosphaerella again dominated most T-RFLP profiles. The data suggest that two fragments (147 and 149 bp), although not confirmed to represent separate taxa, were specific to host plant species. Preliminary data from samples of the same species of grass collected in states along the Gulf coast (FL, LA, MS, AL) confirm all conclusions drawn for samples collected along the east coast, including the higher diversity on S. patens, omnipresence of P. spartinicola and P. halima, and species-specificity of fragments at 147 and 149 bp.},
keywords = {ascomycete, diversity, fungi, GCE, molecular, mycology, salt marsh, spartina},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/Justine_Lyons_PhD_2007.pdf},
author = {Lyons, Justine I.}
@article {67964,
title = {The role of nitrogen in chromophoric and fluorescent dissolved organic matter formation},
journal = {Marine Chemistry},
volume = {103},
year = {2007},
pages = {46-60},
abstract = {Microbial and photochemical processes affect chromophoric dissolved organic matter (CDOM) dynamics in the ocean. Some evidence suggests that dissolved nitrogen plays a role in CDOM formation, although this has received little systematic attention in marine ecosystems. Coastal seawater incubations were carried out in the presence of model dissolved organic nitrogen (DON: amino sugars and amino acids) and dissolved inorganic nitrogen (DIN) compounds to assess their role in biological and photochemical production of CDOM. For several of the dissolved N compounds, microbial processing resulted in a pulse of CDOM that was mainly labile, appearing and disappearing within 7 days. In contrast, a net loss of CDOM occurred when no N was added to the microbial incubations. The greatest net biological CDOM formation was found upon addition of amino sugars (formation of fluorescent, mostly labile CDOM) and tryptophan (formation of non-fluorescent, refractory CDOM). Photochemical formation of CDOM was only found with tryptophan, the one aromatic compound tested. This CDOM was highly fluorescent, with excitation},
keywords = {chromophoric, dom, fluorescent, GCE, nitrogen, organic matter},
doi = {10.1016/j.marchem.2006.06.003},
author = {Biers, Erin J. and Zepp, Richard G. and Moran, Mary Ann.}
@inbook {67968,
title = {A saltmarsh decomposition system and its ascomycetous laccase genes},
booktitle = {Fungi in the Environment},
year = {2007},
pages = {357-370},
publisher = {Cambridge University Press},
organization = {Cambridge University Press},
address = {Cambridge, UK},
abstract = {Recently it has been discovered that fungal laccases can function as effective catalysts in oxidation of lignin, given the right conditions. We found that nearly all of the major and minor species of the ascomycete community of the saltmarsh grass smooth cordgrass (Spartina alterniflora) have laccase genes. Laccase genes of the three predominant decomposer species, two phaeosphaerias and a mycosphaerella, were present as the major fungal laccase genes found by PCR in naturally decaying cordgrass blades at both early (upright) and late (recumbent) stages of decay of attached blades. The two phaeosphaerias each possessed more than one laccase-gene type, and the types exhibited different frequencies within clone libraries for the two decay stages. The ubiquitous occurrence of multiple laccase genes reinforces the conclusion that cordgrass ascomycetes convert even the fibrous parts of cordgrass into fungal mass (0.5 kg fungal mass m^-2 marsh y^-1), enabling effective processing of the grass into the marsh foodweb.},
keywords = {acscomycetes, GCE, laccase genes, lignocellulose decay, phaeosphaeria, saltmarsh, spartina alterniflora},
author = {Newell, S. Y. and Lyons, Justine I. and Moran, Mary Ann.},
editor = {Watkinson, S.}
@article {67972,
title = {Savannah River, Georgia: Science to support adaptive implementation of environmental flows to a large coastal river, floodplain, and estuary},
journal = {Water Resources Impact},
volume = {9},
year = {2007},
pages = {21-24},
abstract = {A look at the Savannah River shows how a flood prone system can be managed to protect homes and cities while sustaining the estuary and other areas dependent on its water flows by being adaptive and responsive.},
keywords = {coastal, estuary, flows, GCE, management, savannah river},
author = {Wrona, A. B. and Batzer, Darold. and Alber, Merryl. and Sharitz, Rebecca R.}
@article {68052,
title = {Temperature controls a llatitudinal gradient in the proportion of waterhsed nitrogren exported to coastal ecosystems},
journal = {Biogeochemistry},
volume = {85},
year = {2007},
pages = {333-346},
abstract = {Increased export of biologically available nitrogen (N) to the coastal zone is strongly linked to eutrophication, which is a major problem in coastal marine ecosystems (NRC (2000) Clean Coastal Waters: Understanding and Reducing the Effects of Nutrient Pollution. National Academy Press, Washington, DC; Bricker et al. (1999) National Estuarine Eutrophication Assessment. Effects of nutrient enrichment in the nation},
keywords = {GCE, GIS, gradient, latitude, nitrogen, signature publication},
doi = {10.1007/s10533-007-9144-9},
url = {http://www.springerlink.com/content/u0146q6420406j04/},
author = {Schaefer, Sylvia C. and Alber, Merryl.}
@article {68055,
title = {Temporal and spatial trends in nitrogen and phosphorus inputs to the watershed of the Altamaha River, Georgia, USA},
journal = {Biogeochemistry},
volume = {86},
year = {2007},
pages = {231-249},
abstract = {The watershed of the Altamaha River, Georgia, is one of the largest in the southeastern U.S., draining 36,718 km2 (including parts of metro Atlanta). We calculated both nitrogen (fertilizer, net food and feed import, atmospheric deposition, and biological N fixation in agricultural and forest lands) and phosphorus (fertilizer and net food and feed import) inputs to the watershed for 6 time points between 1954 and 2002. Total nitrogen inputs rose from 1,952 kg N km-2 yr-1 in 1954 to a peak of 3,593 kg N km-2 yr-1 in 1982 and then declined to 2,582 kg N km-2 yr-1 by 2002. Phosphorus inputs rose from 409 kg P km-2 yr-1 in 1954 to 532 kg P km-2 yr-1 in 1974 before declining to 412 kg P km-2 yr-1 in 2002. Fertilizer tended to be the most important input of both N and P to the watershed, although net food and feed import increased in importance over time and was the dominant source of N input by 2002. When considered on an individual basis, fertilizer input tended to be highest in the middle portions of the watershed (Little and Lower Ocmulgee and Lower Oconee sub-watersheds) whereas net food and feed imports were highest in the upper reaches (Upper Oconee and Upper Ocmulgee sub-watersheds). Although the overall trend in recent years has been towards decreases in both N and P inputs, these trends may be offset due to continuing increases in animal and human populations.},
keywords = {altamaha river, GCE, georgia, nitrogen, phosphorus, spatial trends, temporal trends, watershed},
doi = {10.1007/s10533-007-9155-6},
url = {http://www.springerlink.com/content/233v31u287300447/},
author = {Schaefer, Sylvia C. and Alber, Merryl.}
@article {68087,
title = {Variations of turbulent flow with river discharge in the Altamaha River Estuary, Georgia},
journal = {Journal of Geophysical Research - Oceans},
volume = {112},
year = {2007},
abstract = {Turbulent flow characteristics under two significantly different river discharge periods were studied in the Altamaha River Estuary, GA using a variety of moored instrumentation, combined with detailed water column profiling from an anchored vessel. Estimates of the Reynolds stress, shear production (P), and dissipation rate (epsilon) were derived and compared for the two contrasting river conditions which essentially characterized the estuary as weakly stratified during low discharge (2001) and partially mixed during high discharge (2003). Wave effects were removed from the measurement of turbulent kinetic energy (TKE) using a linear filtration method and a -5/3 slope was fit for an indirect measurement of epsilon. We suggest two possible mechanisms for observed flood/ebb asymmetries in the shear production of energy: wave-induced bottom roughness change or the competing effects of the barotropic and baroclinic pressure gradients. For 2001 the buoyancy flux was estimated by calculating the dissipation of temperature variance from rapidly sampled temperature time series over two different tidal cycles. The mixing efficiency tau approached 0.25 but was on average 0.05. The mixing rate depended on the flow and stratification with highest values of 200 cm2/s during maximum flow and weakest stratification and lowest values of .1 cm2/s during low flow and greater stratification. A balance of production and dissipation of energy was achieved only during ebb tide in 2001, implying that turbulent transport of TKE maybe a consideration since buoyancy dissipation is too small for 2001 and would only enhance the imbalance further in 2003 because of strong stratification that exists during the flood and ebb tide.},
keywords = {altamaha river, estuary, GCE, georgia, oceanography, physics, river discharge, turbulent flow},
doi = {10.1029/2006JC003763},
author = {Di Iorio, Daniela. and Kang, KiRyong.}
@article {68128,
title = {Air-sea exchange of carbon dioxide in ocean margins: A province-based synthesis},
journal = {Geophysical Research Letters},
volume = {33},
year = {2006},
pages = {L12603},
abstract = {In determining global sea-to-air CO2 flux from measurements or models, the ocean margin has not been resolved from the land or the open ocean. Recent studies have indicated that shelves can be either a large sink or a source for atmospheric CO2. This CO2 sink/source term may substantially alter our current view of the global carbon budget for land and oceans. However, past fieldwork and synthesis have focused on a few shelves in the northern temperate zone while the vast majority of other shelves are ignored. By dividing the highly heterogeneous shelves into seven provinces, we suggest that the continental shelves are a sink for atmospheric CO2 at mid-high latitudes (-0.33 Pg C a-1) and a source of CO2 at low latitudes (0.11 Pg C a-1). Warm temperature and high terrestrial organic carbon input are most likely responsible for the CO2 release in low latitude shelves.},
keywords = {atmosphere, carbon dioxide, CO2, GCE, ocean margins, synthesis},
doi = {10.1029/2006GL026219},
author = {Cai, Wei-Jun. and Dai, Minhan. and Wang, Yongchen.}
@article {68174,
title = {The calculation of estuarine turnover times using freshwater fraction and tidal prism models: a critical evaluation},
journal = {Estuaries and Coasts},
volume = {29},
year = {2006},
pages = {133-146},
abstract = {Freshwater fraction and tidal prism models are simple methods for estimating the turnover time of estuarine water. The freshwater fraction method prominently features flushing by freshwater inflow and has sometimes been criticized because it appears not to include flushing by seawater, but this is accounted for implicitly because the average estuary salinity used in the calculation reflects all the processes that bring seawater into the estuary, including gravitational circulation and tidal processes. The model relies on measurable salinity differences among water masses and so must be used for estuaries with substantial freshwater inflow. Tidal prism models are based on flushing by flood tide inflow and ignore seawater inflow due to gravitational circulation. These models should only be applied to estuaries with weak or nonexistent gravitational circulation, which are generally those with little freshwater inflow. Using a framework that is less ambiguous and more directly applicable to the estimation of turnover times than those used previously, this paper critically examines the application of tidal prism models in well-mixed estuaries with complete tidal exchange, partial ebb return, or incomplete flood mixing and in partially mixed estuaries. Problems with self-consistency in earlier versions of these models also apply to the budgeting procedure used by the LOICZ (Land-Ocean Interactions in the Coastal Zone) program. Although freshwater fraction and tidal prism models are different approaches to estimating turnover times in systems with very different characteristics, consistent derivation shows that these models have much in common with each other and that they yield equivalent values that can be used to make comparisons across systems.},
keywords = {estuary, freshwater, GCE, modeling, salinity, tidal prism, turnover times},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/GCEPub287_Sheldon_Alber_Estuaries_2006.pdf},
author = {Sheldon, Joan E. and Alber, Merryl.}
@article {68222,
title = {Cold event in the South Atlantic Bight during summer of 2003: Anomalous hydrographic and atmospheric conditions},
journal = {Journal of Geophysical Research},
volume = {111},
year = {2006},
pages = {C06007},
abstract = {Unusually cold seawater temperatures were observed along much of the U.S. eastern seaboard during the summer of 2003. In this study, hydrographic and atmospheric observations from spring through summer were analyzed to track the evolution of the cold water event in the South Atlantic Bight (SAB) and investigate links to various forcing mechanisms. The hydrographic observations included 13 cross-shelf transects over the central region of the SAB, surface temperature time series from several NDBC stations, and bottom temperatures from a mid shelf mooring. Atmospheric data were obtained from NDBC stations. Additional data included water level from NOS stations and river discharge from USGS stations. The conditions observed during spring and summer of 2003 were compared with climatological values. Record precipitation and increased river discharge during spring produced strong salinity stratification over the inner and mid shelf. Anomalously intense and persistent upwelling-favorable winds were present from May until August. On the mid and outer shelf the resulting upwelling and subsurface shoreward penetration of cold water acted as a feedback mechanism to preserve the stratified conditions through the summer. The characteristics of the upwelled water corresponded to water from the lower part of the Gulf Stream water column. On the shelf the resulting temperature values under the thermocline were significantly lower than climatological temperatures by 5},
keywords = {anomalous, cold, GCE, hydrographic, oceanography, south atlantic bight},
doi = {10.1029/2005JC003105},
url = {http://www.agu.org/journals/jc/jc0606/2005JC003105/2005JC003105.pdf},
author = {Aretxabaleta, A. and Nelson, James R. and Blanton, Jackson O. and Seim, Harvey E. and Werner, F. E. and Bane, J M and Weisberg, R.}
@mastersthesis {68261,
title = {Culture-independent Characterization Of DOC-Transforming Bacterioplankton in Coastal Seawater},
year = {2006},
pages = {182},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {Bacterially-mediated transformation of aromatic monomers and organic osmolytes, two important components of the dissolved organic (DOC) pool in coastal seawater, is significant in the biogeochemical cycling of essential elements including carbon, sulfur and nitrogen. A study of bacterioplankton responding to the addition of 20 uM dimethylsulfoniopropionate (DMSP), a sulfur-containing organic osmolyte, suggested that a subset of the bacterial community could degrade DMSP. Cells developing high nucleic acid content in the presence of DMSP included members of alpha-Proteobacteria (mainly in the Roseobacter clade), beta-Proteobacteria and gamma-Proteobacteria, and a lower number of Actinobacteria and Bacteroidetes. The relative importance of DMSP-active taxa varied seasonally. Another study tested whether aromatic monomers and organic osmolytes are transformed by specialist bacterial taxa. The taxonomy of coastal bacterioplankton responding to the addition of 100 nM organic osmolyte [DMSP or glycine betaine (GlyB)] or aromatic monomer [para-hydroxybenzoic acid (pHBA) or vanillic acid (VanA)] was determined using incorporation of bromodeoxyuridine (BrdU) to track actively growing cells. 16S rDNA clones of active bacterioplankton indicated that both types of DOC were transformed by bacterial assemblages composed of the same major taxa, including Actinobacteria, Bacteroidetes, alpha-Proteobacteria (mainly members of the Roseobacter clade), beta-Proteobacteria, and gamma-Proteobacteria (mainly members of Altermonadaceae, Chromatiaceae, Oceanospirillaceae and Pseudomonadaceae). The relative abundance of each taxon differed, however. Members of the OM60/241 and OM185, SAR11, SAR86 and SAR116 bacterioplankton groups in the active cell group indicated the ability to transport and metabolize these compounds by these ubiquitous but poorly described environmental clusters. In a final study, the phylogenetic diversity and functional capability of bacterioplankton stimulated by the addition of DMSP or VanA were explored by metagenomic analysis. Metagenomic sequences revealed a similar taxonomic structure for the bacterioplankton enriched with both DOC types, and were generally consistent with the PCR-based 16S rDNA analysis of the same template. Likewise, similar distribution patterns of functional gene categories were found for the two enriched bacterioplankton communities. These results indicate that DMSP and VanA were transformed by metabolic generalists capable of degrading both compounds. These studies provide insights into the response of coastal bacterial communities to changing environmental conditions in an ecological time frame.},
keywords = {aromatic monomers, brdu incorporation, dmsp, DOC DEGRADATION, flow cytometric cell sorting, GCE, marine bacteria, metagenomics, microbiology, organic osmolytes, pyrosequencing},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/Mou_Xiaozhen_PhD_2006.pdf},
author = {Mou, Xiaozhen.}
@article {68272,
title = {Development of Hypoxia in Well-mixed Subtropical Estuaries in the Southeastern USA},
journal = {Estuaries and Coasts},
volume = {29},
year = {2006},
pages = {665},
abstract = {Estuaries throughout much of the South Atlantic Bight (southeastern U.S.) have been considered to be relatively pristine, but are now experiencing elevated concentrations of both organic and inorganic nutrients. As is true in many parts of the world, this eutrophication is correlated with coastal population growth. These estuaries have been assumed to be immune from extended hypoxia, in large part because they are well mixed and do not generally exhibit the water column stratification that is traditionally associated with low concentrations of dissolved oxygen. Data presented here show long-term (19 yr) decreases in dissolved oxygen in surface waters of the Skidaway estuary, a pattern that is occurring throughout coastal Georgia. More limited data from bottom waters exhibit the same trend. The decreases in dissolved oxygen occurred at the same time as observed increases in inorganic and organic nutrients and in bacteria concentrations, implying an increase in heterotrophic activity. These observations suggest that traditional paradigms long applied to stratified estuaries, wherein the cycle that leads to hypoxia is initiated by the uptake of inorganic nutrients by autotrophs that are then decomposed below the pycnocline, may need revision for well-mixed estuaries. Heterotrophic community metabolism, stimulated by anthropogenic loading of organic and inorganic nutrients, can overwhelm even vigorous vertical mixing and horizontal exchange to gradually cause declining oxygen concentrations and eventually hypoxia.},
keywords = {estuaries, eutrophication, GCE, hypoxia, oxygen, pollution, well-mixed},
author = {Verity, Peter G. and Alber, Merryl. and Bricker, Suzanne B.}
@book {68274,
title = {Development of wetland plant communities},
series = {Ecology of freshwater and estuarine wetlands},
year = {2006},
pages = {177-241},
publisher = {University of California Press},
organization = {University of California Press},
address = {Berkeley},
keywords = {ecology, estuarine, freshwater, GCE, wetlands},
author = {Sharitz, Rebecca R. and Pennings, Steven C.},
editor = {Sharitz, Rebecca R.}
@article {68379,
title = {Estimates of flushing times, submarine groundwater discharge, and nutrient fluxes to Okatee Estuary, South Carolina},
journal = {Journal of Geophysical Research},
volume = {111},
year = {2006},
abstract = {A physical model based on determining the fraction of the tidal prism that returns to the estuary on the next high tide is used to estimate the flushing time of the Okatee River estuary. The return flow factor (b) of 0.81 yields a flushing time of 2 days. A mass balance model of 228Ra and salinity is also used to estimate b. This model yields an average b = 0.79, virtually the same as the physical model. A third model based on the decay of 224Ra relative to 228Ra is used to determine the apparent age of water in the estuary. These ages range from 1.6 to 5 days, with an average of 3.4 days. These three independent estimates are in remarkably close agreement, certainly within the error of each estimate. We use these residence times to develop a mass balance model for the radium isotopes in the Okatee estuary. We consider decay, mixing, sedimentary input, river input, and submarine groundwater discharge (SGD). The major loss term for each isotope is mixing with water in Port Royal Sound; the major input for each isotope is SGD. At steady state these terms must balance. Knowing the water age and the radium isotope composition of groundwater entering the Okatee allows us to estimate an average SGD flux of 1 m3/s. The SGD flux is a factor of 3},
keywords = {flushing time, GCE, groundwater, hydrology, nutrient fluxes, okatee, radium, south carolina, submarine},
doi = {10.1029/2005JC003041},
author = {Moore, Willard S. and Blanton, Jackson O. and Joye, Samantha B.}
@article {68532,
title = {An Investigation of Salt Marsh Dieback in Georgia using Field Transplants},
journal = {Estuaries and Coasts},
volume = {29},
year = {2006},
pages = {54-62},
abstract = {In 2001 and 2002, Georgia salt marshes experienced a dieback event that affected more than 800 ha throughout the coastal zone. The dieback event was unprecedented in the state and affected both Spartina alterniflora and Juncus roemerianus. A transplant study was conducted from May to October 2003 to determine if healthy plants could survive in dieback areas. Transplants were carried out at two locations on the Georgia coast in areas of S. alterniflora dieback along the banks of tidal creeks, in an area of S. alterniflora dieback in the mid marsh, and in a J. roemerianus dieback area in the mid marsh. Transplant survival was nearly 100\% and growth (measured as increases in the height of the 5 tallest stems and the number of stems per experimental pot) was observed in both healthy (control) and dieback areas. J. romerianus grew more slowly than S. alterniflora, with no observed increase in stem height and an average 38\% increase in stem density as compared to an average 57\% increase in stem height and 137\% increase in stem density in S. alterniflora. Differences in growth were inconsistent but in most cases no significant differences were observed between healthy and dieback areas. Soil characteristics measured over the course of the experiment were generally comparable between healthy and dieback areas (redox potential averaged 69},
keywords = {dieback, disturbance, GCE, georgia, salt marsh},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/GCEPub281_Ogburn_Alber_Estuaries_2005.pdf},
author = {Ogburn, Matthew B. and Alber, Merryl.}
@article {68601,
title = {Microbial and geochemical ramifications of salinity intrusion into tidal freshwater sediments},
journal = {Journal of Geophysical Research},
volume = {111},
year = {2006},
pages = {G01009},
abstract = {The effects of salinity intrusion on the anaerobic microbial and geochemical dynamics of tidal freshwater sediments were investigated using flow-through sediment reactors. In freshwater control sediments, organic matter mineralization was dominated by methanogenesis (62\%), followed by sulfate reduction (18\%), denitrification (10\%), and iron reduction (10\%). Upon salinity intrusion, nutrient (ammonium, silicate, phosphate) concentrations increased and rates of methanogenesis declined. Iron-oxide bioavailability increased and microbial iron reduction appeared to account for >60\% of organic matter oxidation for several days after salinity intrusion. However, sulfate reduction was the dominant pathway (>50\%) of organic matter oxidation within 2 weeks of salinity intrusion, and accounted for >95\% of total organic matter mineralization after 4 weeks. Total in situ sediment organic matter mineralization doubled following salinity intrusion. Increased nutrient release, decreased methanogenesis and a rapid shift to sulfate reduction, with a coincident increase overall organic matter mineralization, accompanied salinity intrusion into previously freshwater riverine sediments.},
keywords = {freshwater sediments, GCE, geochemistry, microbial, mineralization, organic matter, PATHWAYS, salinity, tidal},
doi = {10.1029/2005JG000071},
author = {Weston, Nathaniel B. and Dixon, Ray E. and Joye, Samantha B.}
@mastersthesis {68670,
title = {Nutrient budgets for watersheds on the southeastern Atlantic coast of the United States: temporal and spatial variation},
year = {2006},
pages = {105},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {Nitrogen budgets were constructed for the watersheds of twelve rivers in the southeastern U.S. following the methodology of the SCOPE project. Total inputs ranged from 2,762-6,232 kg/km2/yr, with the largest contributions from fertilizer and net food/feed import. Export to the estuaries of these rivers was positively related to inputs and averaged 9\%. In contrast, reported export to estuaries further north averaged 25\%. These differences are consistent with temperature-driven changes in denitrifier activity and suggest a possible control for watershed nitrogen export. In order to evaluate changes in nutrient input over time, nitrogen and phosphorus budgets were constructed for the watershed of the Altamaha River estuary in Georgia for 1954, 1974, and 1992. Nutrient inputs increased between 1954 and 1974 and decreased in 1992 (from 2,007 to 3,553 to 2,977 kg N/km2/yr and 408 to 532 to 340 kg P/km2/yr). These changes were largely driven by trends in fertilizer use.},
keywords = {agriculture, atlantic coast, climate change, coastal, denitrification, GCE, nutrient budgets, reactive nitrogen, spatial, stream export, temperature, temporal, watersheds},
author = {Schaefer, Sylvia C.}
@inbook {68681,
title = {Optical remote sensing techniques to estimate phytoplankton chlorophyll a concentrations in coastal waters with varying suspended matter and CDOM concentrations.},
booktitle = {Remote Sensing of Aquatic Coastal Ecosystem Processes: Science and Management Applications},
year = {2006},
pages = {27 - 79},
publisher = {Springer},
organization = {Springer},
edition = {1st edition (February 28, 2006)},
address = {Netherlands},
keywords = {cdom, chlorophyll a, coastal remote sensing, GCE, phytoplankton, total suspended matter},
author = {Schalles, John F.},
editor = {Ledrew, E.F.}
@inbook {68687,
title = {Oxygen, carbon dioxide, and estuarine condition},
booktitle = {Changing Land Use Patterns in the Coastal Zone: Managing Environmental Quality in Rapidly Developing Regions Environmental Quality in Rapidly Developing Regions},
year = {2006},
publisher = {Springer-Verlag},
organization = {Springer-Verlag},
address = {New York},
keywords = {carbon dioxide, CO2, estuarine condition, estuary, GCE, oxygen},
author = {Pomeroy, Lawrence R. and Cai, Wei-Jun.},
editor = {Rawson, Mac V.}
@mastersthesis {68699,
title = {Patterns of plant diversity in two salt marsh regions},
year = {2006},
pages = {70},
school = {University of Houston},
address = {Houston, Texas},
abstract = {Although ecologists have been interested in explaining the diversity of ecological systems for many years, there is still no generally accepted theory to explain what determines diversity. Patterns of diversity are determined by which species are able to colonize a particular site and persist in a particular abiotic environment, and by biological interactions between species that may expand or contract their range across an abiotic gradient. By examining these patterns we can begin to understand which biotic and abiotic mechanisms are important for shaping the overall diversity of a system. I compared the salt marshes of Texas to those of Georgia to determine what differences in plant diversity patterns existed between these two systems with similar species pools and general abiotic environments. Both Gulf Coast and Atlantic Coast salt marshes are tidal systems and therefore plants must be tolerant to flooding, salinity, and anoxia. The major abiotic difference between the salt marshes of these two regions is the relatively irregular schedule and lower amplitude of tides in Texas. Tidal schedule and amplitude might affect plant distribution patterns by creating abiotic conditions that vary over time as much or more than over space, thereby altering competitive relationships between plant species.I quantified diversity patterns (richness and relative abundance) on transects across elevation at 59 salt marsh sites in Georgia and 49 sites in Texas. Diversity was measured at global, regional, site, and plot scales to consider processes occurring at all levels. Species pools were similar between regions. Texas had greater diversity at the site and plot scales, which was primarily due to processes occurring at the site level. The greater diversity of Texas was partially explained by the fact that Texas marshes had more middle marsh (a high diversity zone) and less low marsh (a low diversity zone) than Georgia marshes, and by the fact that most species were more widely distributed across the marsh landscape in Texas than in Georgia (i.e., zones were less discrete). Biomass data from a subset of plots and sites suggested that high diversity in Texas was not caused by lower productivity; instead, Texas marshes had greater standing biomass than Georgia marshes. Irregular flooding of Texas marshes might allow more species to exist in the marsh by making abiotic conditions more variable over time, thereby making the outcome of competitive interactions less predictable and rapid.This work suggests that Gulf Coast marshes may function differently in some ways than Atlantic Coast marshes. Managers of Gulf Coast marshes should not assume that paradigms based on the Atlantic Coast will automatically apply. In addition, because salt marsh diversity is determined by site-scale processes, protection efforts should focus on maintaining a range of different marsh types rather than simply maximizing the total marsh acreage protected in a region.},
keywords = {diversity, GCE, georgia, plant, salt marsh, species richness, texas},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/Kunza_MS_Thesis_2006.pdf},
author = {Kunza, Amy E.}
@article {68740,
title = {Pore water stoichiometry of terminal metabolic products, sulfate, and dissolved organic carbon and nitrogen in intertidal creek-bank sediments},
journal = {Biogeochemistry},
volume = {77},
year = {2006},
pages = {375-408},
abstract = {Porewater equilibration samplers were used to obtain porewater inventories of inorganic nutrients (NH4 +, NOx, PO4 3-), dissolved organic carbon (DOC) and nitrogen (DON), sulfate (SO4 2-), dissolved inorganic carbon (DIC), hydrogen sulfide (H2S), chloride (Cl-), methane (CH4) and reduced iron (Fe2+) in intertidal creek-bank sediments at eight sites in three estuarine systems over a range of salinities and seasons. Sulfate reduction (SR) rates and sediment particulate organic carbon (POC) and nitrogen (PON) were also determined at several of the sites. Four sites in the Okatee River estuary in South Carolina, two sites on Sapelo Island, Georgia and one site in White Oak Creek, Georgia appeared to be relatively pristine. The eighth site in Umbrella Creek, Georgia was directly adjacent to a small residential development employing septic systems to handle household waste. The large data set (>700 porewater profiles) offers an opportunity to assess system-scale patterns of porewater biogeochemical dynamics with an emphasis on DOC and DON distributions. SO4 2- depletion (SO4 2-)Dep was used as a proxy for SR, and (SO4 2-)Dep patterns agreed with measured (35S) patterns of SR. There were significant system-scale correlations between the inorganic products of terminal metabolism (DIC, NH4 + and PO4 3-) and (SO4 2-)Dep, and SR appeared to be the dominant terminal carbon oxidation pathway in these sediments. Porewater inventories of DIC and (SO4 2-)Dep indicate a 2:1 stoichiometry across sites, and the C:N ratio of the organic matter undergoing mineralization was between 7.5 and 10. The data suggest that septic-derived dissolved organic matter with a C:N ratio below 6 fueled microbial metabolism and SR at a site with development in the upland. Seasonality was observed in the porewater inventories, but temperature alone did not adequately describe the patterns of (SO4 2-)Dep, terminal metabolic products (DIC, NH4 +, PO4 3-), DOC and DON, and SR observed in this study. It appears that production and consumption of labile DOC are tightly coupled in these sediments, and that bulk DOC is likely a recalcitrant pool. Preferential hydrolysis of PON relative to POC when overall organic matter mineralization rates were high appears to drive the observed patterns in POC:PON, DOC:DON and DIC:DIN ratios. These data, along with the weak seasonal patterns of SR and organic and inorganic porewater inventories, suggest that the rate of hydrolysis limits organic matter mineralization in these intertidal creek-bank sediments.},
keywords = {dissolved organic matter, dom, GCE, inorganic, metabolites, pore water, redox, stoichiometry},
author = {Weston, Nathaniel B. and Porubsky, William P. and Samarkin, Vladimir. and MacAvoy, Steven E. and Erickson, Matthew. and Joye, Samantha B.}
@inbook {68742,
title = {Potential for groundwater-derived carbon, nitrogen and phosphorus inputs to coastal ecosystems in South Carolina and Georgia},
booktitle = {Implications of Land Use Change to Coastal Ecosystems},
year = {2006},
pages = {139-167},
publisher = {Springer-Verlag},
organization = {Springer-Verlag},
address = {New York},
keywords = {carbon, coastal, GCE, georgia, groundwater, inputs, nitrogen, phosphorus, south carolina},
author = {Joye, Samantha B. and Bronk, Deborah A. and Koopmans, Dirk. and Moore, Willard S.},
editor = {Rawson, Mac V.}
@mastersthesis {68752,
title = {Primary production, nitrogen cycling and the ecosystem role of mangrove microbial mats on Twin Cays, Belize},
year = {2006},
pages = {157},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {The seasonal variability of porewater nutrient concentrations, metabolism, nitrogen cycling (denitrification and nitrogen fixation), and primary production (oxygenic and anoxygenic photosynthesis and chemoautotrophy) was examined in benthic mangrove environments on Twin Cays, Belize. Twin Cays mangroves exhibit a tree-height gradient from tall seaward fringe trees, through a transition of intermediate tree heights to short dwarf trees surrounding interior ponds and lagoons. Detailed investigations of steady state porewater profiles of nutrients and terminal metabolic products in dwarf mangrove soils revealed strong seasonal differences in salinity, organic carbon and nitrogen inventories, redox conditions and reduced manganese concentrations. Substantial rates of organic matter remineralization were coupled primarily to sulfate reduction. Redox conditions contributed to variability in mat nitrogen fixation and denitrification response to nutrient addition, while dissolved organic carbon did not. Nitrogen fixation was controlled primarily by the sensitivity of nitrogenase to oxygen inhibition, whereas denitrification was limited by nitrate availability. Community composition of photosynthetic organisms appeared to be controlled by light fluctuations due to mangrove canopy light gaps and by differential tolerance to environmental stresses such as desiccation or nitrogen limitation. Dwarf mangrove cyanobacteria-dominated microbial mats achieved a high biomass of photopigments in well-illuminated soils. Transition and fringe soils were more shaded and contained diatoms and green algae and less cyanobacteria and anoxygenic photosynthetic bacteria than in dwarf soils. Oxygenic photosynthesis was the primary mode of carbon fixation (56\%) in all habitats under full sun, with a lesser contribution by anoxygenic photosynthesis (32\%) and chemoautotrophy (12\%). In situ light conditions underscore the gradient from highest rates of carbon fixation in dwarf mangrove habitat mats -2-1(0.21 g C m d) to diminished rates in shaded transition and fringe mangrove habitat mats (0.08 -2-1and 0.05 g C m d, respectively). Well-lit mats associated with dwarf mangrove habitats fix 18-20\% of the net primary productivity of Twin Cays},
keywords = {anoxygenic photosynthesis, benthic metabolism, carbon fixation, chemoautotrophy, cyanobacteria, denitrification, desiccation, GCE, mangrove, microbial mat, nitrogen fixation, oxygenic photosynthesis, porewater nutrients, primary production, respiration},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/Lee_Rosalynn_Y_200612_PhD.pdf},
author = {Lee, Rosalynn Y.}
@inbook {68788,
title = {The relationship of hydrodynamics and morphology in tidal-creek and salt-marsh systems in South Carolina and Georgia},
booktitle = {Implications of changing land use patterns to coastal ecosystems},
year = {2006},
pages = {93-107},
publisher = {Springer-Verlag},
organization = {Springer-Verlag},
address = {New York, NY},
abstract = {Salt marshes, typical of those found in South Carolina and Georgia, are covered and un-covered approximately twice daily by the rise and fall of the tide. Salt water is transported to the marshes by an array of tidal creeks ranging from 0 to 15 meters in depth and 5 to 500 meters in width. The water fills the creeks on the rising tide and then spills out into the marsh. As the tides fall, the creeks, starting first with the smallest, collect the water much as do the capillary blood vessels in mammals, and convey it to ever-larger creeks to where it is eventually transported into the sounds and estuaries. The banks of tidal creeks undergo considerable sediment erosion, while marsh surfaces are areas of sediment deposition, allowing them to keep pace with sea-level rise. When the marshes and creeks are treated as a whole, one sees that the water surface area changes from its smallest value at spring-tide low water to its maximum at spring-tide high water. The areas encompassed by neap tide fit somewhere in between. Thus, one can derive curves to estimate the variation of the water surface area in the salt marsh-tidal creek complex as a function of water depth. These curves, called hypsometric curves, are needed to estimate the flushing and flooding potential of a marsh. To understand how the hypsometry of a salt marsh system can be determined one can use an example from a small system of tidal creeks in and around the Okatee River in South Carolina. A series of six airborne aerial images was used to measure flooded water area during the flood phase of the tide. The water level was measured with a pressure sensor at the bottom of the main creek, thus providing a vertical reference level for the corresponding flooded area. The shape of this curve is governed by the morphology of the creek-marsh areas, i.e. distribution of wetted surface area as water level increases in the area of interest. The change in area as depth increases represents a certain volume that covers the marsh from its low-water stage to its high-water stage. This volume, defined as the tidal prism, equals the volume of water that flows through a cross-section of the tidal creek. The growth rate of the prism is equal to the velocity flowing through the cross-section of the creek (an equality based on a principle of fluid dynamics called continuity). The faster the horizontal area increases, the larger the transport of water must be to support the growth of the surface area. While the tide is largely responsible for increases in the area (and depth) covered, water level changes can also be induced by winds along the coast. Winds that blow coastal water to the south pile-up water in the estuaries and sounds, and water level there can increase by 0.5 m or so. Wind from the opposite direction can depress water levels by a comparable amount. There are several management issues associated with strong tidal currents flowing through the creeks. For example, the creation of docks and marinas along a tidal creek will impede flow where impediments did not previously exist. Boats comfortably afloat at the beginning of the project wind up becoming stuck in mud during certain parts of the tidal cycle several years later. The most common solution is to implement a dredging program to remove sediment that was being removed by the high tidal flow that existed before development. Thus, the economic service provided by nature must be subsidized through an expensive dredging program in order to keep the waterway usable. Alternatively, by developing a hypsometric profile for its waterways before development, a community can guide the siting of projects such as marinas, thereby reducing costs to taxpayers in the future. Using principles outlined by Friedrichs and Perry (2001) and Pethick (2001), it seems prudent that planning for development in and adjacent to tidal marshes take account of the natural balance between the tidal transport of water and sediment supply. This means that (1) the heavy marsh grass density must be maintained in order to provide an environment favorable to the settling of suspended sediments, (2) that the natural sediment supply from land should be maintained and (3) the inland migration of the marsh as sea level rises should be anticipated and planned for appropriately.},
keywords = {GCE, hypsometric curve, management, marsh, tidal currents, topography},
author = {Blanton, Jackson O. and Andrade, Francisco A. and Adelaide Ferreira, Marie.},
editor = {Rawson, Mac V.}
@article {68791,
title = {Relative impacts of Littoraria irrorata and Prokelisia marginata on Spartina alterniflora growth},
journal = {Estuaries},
volume = {29},
year = {2006},
pages = {639-644},
abstract = {Spartina alterniflora salt marshes along the southeastern United States are some of the most productive and well studied ecosystems in the world. The role of physicochemical forces in regulating Spartina growth is well understood, while the importance of grazers remains less clear. Recent studies have shown that the abundant marsh periwinkle, Littoraria irrorata, can exert strong control over Spartina through its grazing activities, but relatively little is known about its relative effects in comparison to other marsh plant consumers. To test the relative importance of snail and insect consumers on Spartina biomass, we conducted a 7-mo field experiment testing top-down regulation of Spartina with all combinations of L. irrorata (removed, control, c. 215 periwinkles m22) and Spartina planthopper, Prokelisia marginata (removed, control). Snail removal resulted in a 50\% increase in Spartina biomass while removal of planthoppers had no detectable effect. Planthopper density also increased by 50\% when snails were excluded. In this South Carolina marsh, L. irrorata exerts a stronger top-down control of Spartina than P. marginata. These results indicate trophic cascade regulation of Spartina salt marsh is more likely to occur through the predator(s)-Littoraria-plant interaction than through the predator(s)-Prokelisia-plant relationship.},
keywords = {GCE, littoraria irrorata, molluscs, prokelisia marginata, spartina alterniflora},
author = {Gustafson, Danny J. and Kilheffer, Jeff. and Silliman, Brian R.}
@article {68934,
title = {Tidal circulation and energy dissipation in a shallow, sinuous estuary},
journal = {Ocean Dynamics},
volume = {56},
year = {2006},
pages = {360-375},
abstract = {The tidal dynamics in a pristine, mesotidal (>2 m range), marsh-dominated estuary are examined using moored and moving vessel field observations. Analysis focuses on the structure of the M2 tide that accounts for approximately 80\% of the observed tidal energy, and indicates a transition in character from a near standing wave on the continental shelf to a more progressive wave within the estuary. A slight maximum in water level (WL) occurs in the estuary 10},
keywords = {circulation, energy dissipation, estuary, GCE, oceanography, tides},
doi = {10.1007/s10236-006-0078-x},
url = {http://www.springerlink.com/content/q5173t34035t5trj/?p=cc0ba380916a414a9619d6b49edbe176\&pi=1},
author = {Seim, Harvey E. and Blanton, Jackson O. and Elston, Susan A.}
@article {69018,
title = {Analysis of microbial gene transcripts in environmental samples},
journal = {Applied and Environmental Microbiology},
volume = {71},
year = {2005},
pages = {4121-4126},
abstract = {We analyzed gene expression in marine and freshwater bacterioplankton communities by the direct retrieval and analysis of microbial transcripts. Environmental mRNA, obtained from total RNA by subtractive hybridization of rRNA, was reverse transcribed, amplified with random primers, and cloned. Approximately 400 clones were analyzed, of which ?80\% were unambiguously mRNA derived. mRNAs appeared to be from diverse taxonomic groups, including both Bacteria (mainly alpha- and gamma-Proteobactria) and Archaea (mainly Euryarchaeota). Many transcripts could be linked to environmentally important processes such as sulfur oxidation (soxA), assimilation of C1 compounds (fdh1B), and acquisition of nitrogen via polyamine degradation (aphA). Environmental transcriptomics is a means of exploring functional gene expression within natural microbial communities without bias toward known sequences, and provides a new approach for obtaining community- specific variants of key functional genes.},
keywords = {environmental, GCE, gene, genetics, microbial ecology, molecular, transcripts},
author = {Poretsky, Rachel S. and Bano, Nasreen. and Buchan, Alison. and LeCleir, Gary. and Kleikemper, Jutta. and Pickering, Maria. and Pate, Whitney M. and Moran, Mary Ann. and Hollibaugh, James T.}
@mastersthesis {69054,
title = {Biogeochemistry in the coastal zone: changing land use, salinity intrusion, porewater stoichiometry and the mineralization of organic matter in estuarine sediments},
year = {2005},
pages = {188},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {Thirty years of population growth, land use change, and nutrient loading from the subwatersheds of the Altamaha River, GA were analyzed. Population growth, mainly in the upper watershed near the cities of Atlanta and Athens, resulted in increased nitrate delivery to the rivers and transport to the coastal zone. Delivery of freshwater appears to be declining, due to climate change and water withdrawal within the watershed. The effects of upriver salinity intrusion on the biogeochemistry of sediments from the tidal freshwater portion of the Altamaha River were investigated. Methanogenesis, which dominated in the freshwater sediments, declined quickly following salinity intrusion. Sulfate reduction was the dominant pathway of microbial organic matter mineralization within two weeks of salinity intrusion, although increased iron-oxide availability during initial salinity intrusion appears to have stimulated high rates of microbial iron reduction for a short period. Salinity-driven desorption of ammonium and increased rates of silica and phosphorus mineral dissolution following salinity intrusion increased overall export of ammonium, phosphate and silicate from salinity-impacted sediments. The mineralization of complex organic matter in sediments is mediated by a diverse consortium of microbes that hydrolyze, ferment, and terminally oxidize organic compounds. Patterns of estuarine sediment biogeochemistry, focusing on the role of dissolved organic carbon (DOC) and nitrogen, were determined with a multi-site, multi-season survey of estuarine porewater profiles in Georgia and South Carolina. This survey demonstrated system-scale correlations between the inorganic products of terminal metabolism (dissolved inorganic carbon, ammonium and phosphate) and sulfate depletion. DOC, as the substrate for terminal metabolism, was not correlated with other variables indicating that production and consumption of DOC were tightly coupled, and bulk DOC is largely a recalcitrant pool. Controls on the coupling between the hydrolytic/fermentative and terminal metabolic bacterial communities in estuarine sediments were further investigated using anaerobic flow-through bioreactors. We documented the temperature-driven decoupling of the production and consumption of key DOC intermediates due to variable temperature responses of these functional microbial groups. Production of labile DOC exceeded terminal oxidation at colder temperatures, resulting in accumulation of labile DOC. At higher temperatures, potential terminal oxidation rates exceeded those of labile DOC production and labile DOC availability limited rates of terminal oxidation.},
keywords = {biogeochemistry, denitrification, dissolved organic carbon, dissolved organic matter, estuary, fermentation, GCE, hydrolosis, iron reduction, land use, LOADING, methanogenesis, mineralization, nutrient, organic matter, population, porewater, salinity, salinity intrusion, stoichiometry, sulfate reduction, temperature, terminal metabolism, watershed},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/Weston_Nathaniel_PhD_2005.pdf},
author = {Weston, Nathaniel B.}
@article {69130,
title = {Culture-independent identification of bacterioplankton involved in DMSP transformations by flow cytometric cell sorting and subsequent molecular analyses},
journal = {Applied and Environmental Microbiology},
volume = {71},
year = {2005},
pages = {1405-1416},
abstract = {Marine bacterioplankton transform dimethylsulfoniopropionate (DMSP) into the biogeochemically important and climatically active gas dimethylsulfide. In order to identify specific bacterial taxa mediating DMSP processing in a natural marine ecosystem, we amended water samples from a southeastern U.S. salt marsh with 20 uM DMSP and tracked community shifts with flow cytometry (FCM) coupled to 16S rRNA gene analyses. In two out of four seasons studied, DMSP amendments induced the formation of distinct bacterioplankton populations with elevated nucleic acid (NA) content within 24 h, indicative of cells actively utilizing DMSP. The 16S rRNA genes of the cells with and without elevated NA content were analyzed following cell sorting and PCR amplification with sequencing and terminal restriction fragment length polymorphism approaches. Compared to cells in the control FCM populations, bacteria with elevated NA content in the presence of DMSP were relatively enriched in taxa related to Loktanella, Oceanicola, and Sulfitobacter (Roseobacter lineage, alpha-Proteobacteria); Caulobacter (alpha-Proteobacteria); and Brachymonas and Xenophilus (beta-Proteobacteria) in the May-02 sample and to Ketogulonicigenium (Roseobacter lineage, alpha-Proteobacteria) and novel gamma-Proteobacteria in the Sept-02 sample. Our study suggests that diverse bacterioplankton participate in the metabolism of DMSP in coastal marine systems and that their relative importance varies temporally.},
keywords = {bacterioplankton, dmsp, flow cytometry, GCE, molecular biology},
doi = {10.1128/AEM.71.3.1405},
author = {Mou, Xiaozhen. and Moran, Mary Ann. and Stepansuskas, Ramunas. and Gonzalez, Jose M. and Hodson, Robert E.}
@mastersthesis {69136,
title = {Defining science/defining stories: Teachers},
year = {2005},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {This qualitative study investigated teacher understandings and experiences as they came to redefine science through their participation in a program that supports teacher-scientist collaborations in field-based scientific research. This summer residential experience in ecology for teachers was designed to answer the call for opportunities for teachers to conduct real world, long-term scientific inquiry projects and thus provide for greater teacher-as-scientist authenticity in the classroom. The program intended to connect several issues in recent science education literature: the conflict between real science and school science; science knowledge construction; and authentic science experiences for teachers and students. In this field-based research setting, teachers were challenged to expand their understanding of how science is conducted and how science knowledge is constructed. The teachers came to recognize the essential role of exchanging ideas and brainstorming in informal, social settings in the knowledge acquisition process. They recognized that research ideas and the designs of experiments within this research community were not considered rigid or procedural. Instead, they saw those ideas and designs as flexible and under continuous development and revision},
keywords = {collaborations, education, GCE, science knowledge, stories},
author = {Hembree, Patricia A.}
@article {69140,
title = {Depth- and current-induced effects on wave propagation into the Altamaha River Estuary, Georgia},
journal = {Estuarine, Coastal and Shelf Science},
volume = {66},
year = {2005},
pages = {395-408},
abstract = {A study of sea surface wave propagation and its energy deformation was carried out using field observations and numerical experiments over a region spanning the midshelf of the South Atlantic Bight (SAB) to the Altamaha River Estuary, GA. Wave heights on the shelf region correlate with the wind observations and directional observations show that most of the wave energy is incident from the easterly direction. Comparing mid-shelf and inner-shelf wave heights during a time when there was no wind and hence no wave development led to an estimation of wave energy dissipation due to bottom friction with corresponding wave dissipation factor of 0.07 for the gently sloping continental shelf of the SAB. After interacting with the shoaling region of the Altamaha River, the wave energy within the estuary becomes periodic in time showing wave energy during flood to high water phase of the tide and very little wave energy during ebb to low water. This periodic modulation inside the estuary is a direct result of enhanced depth and current-induced wave breaking that occurs at the ebb shoaling region surrounding the Altamaha River mouth at longitude 81.23W. Modelling results with STWAVE showed that depth-induced wave breaking is more important during the low water phase of the tide than current-induced wave breaking during the ebb phase of the tide. During the flood to high water phase of the tide, wave energy propagates into the estuary. Measurements of the significant wave height within the estuary showed a maximum wave height difference of 0.4 m between the slack high water (SHW) and slack low water (SLW). In this shallow environment these wave-current interactions lead to an apparent bottom roughness that is increased from typical hydraulic roughness values, leading to an enhanced bottom friction coefficient.},
keywords = {altamaha river, current, depth, GCE, georgia, physics, propagation, wave},
author = {Kang, KiRyong. and Di Iorio, Daniela.}
@article {69161,
title = {Do individual plant species show predictable responses to nitrogen addition across multiple experiments?},
journal = {Oikos},
volume = {110},
year = {2005},
pages = {547-555},
abstract = {Abstract 1959},
keywords = {ARC, CDR, GCE, KNZ, NWT, SEV},
author = {Pennings, S and Clark, C.M. and Cleland, E.E. and Collins, S. L. and Gough, L. and Gross, K.L. and Milchunas, DG. and Suding, K.N.}
@article {81509,
title = {Do individual plant species show predictable responses to nitrogen addition across multiple experiments?},
volume = {110},
year = {2005},
pages = {547-555},
abstract = {A number of experiments have addressed how increases in nitrogen availability increase the productivity and decrease the diversity of plant communities. We lack, however, a rigorous mechanistic understanding of how changes in abundance of particular species combine to produce changes in community productivity and diversity. Single experiments cannot provide insight into this issue because each species occurs only once per experiment, and each experiment is conducted in only one location; thus, it is impossible from single experiments to determine whether responses of particular species are consistent across environments or dependent on the particular environmental context in which the experiment was conducted. To address this issue, we assembled a dataset of 20 herbaceous species that were each represented in at least 6 different fertilization experiments and tested whether responses were general across experiments. Of the 20 species, one consistently increased in relative abundance and five consistently decreased across replicate experiments. A partially-overlapping group of 8 species displayed responses to nitrogen that varied predictably among experiments as a function of geographic location, neighboring species, or a handful of other community characteristics (ANPP, precipitation, species richness, relative abundance of focal species in control plots, and community composition). Thus, despite modest replication and a limited number of predictor variables, we were able to identify consistent patterns in response of 10 out of 20 species across multiple experiments. We conclude that the responses of individual species to nitrogen addition are often predictable, but that in most cases these responses are functions of the abiotic or biotic environment. Thus, a rigorous understanding of how plant species respond to nitrogen addition will have to consider not only the traits of individual plant species, but also aspects of the communities in which those plants live.},
keywords = {ARC, distichlis, eutrophication, fertilization, GCE, juncus, KNZ, nitrogen, plant, Salicornia, spartina},
author = {Pennings, Steven C. and Clark, Christopher M. and Cleland, Elsa E and Collins, Scott L. and Gough, Laura and Gross, Katherine L. and Milchunas, Daniel G. and Suding, Katherine N.}
@article {69194,
title = {Effect of salinity and inorganic nitrogen concentrations on nitrification and denitri.cation rates in intertidal sediments and rocky bio.lms of the Douro River estuary, Portugal},
journal = {Water Research},
volume = {39},
year = {2005},
pages = {1783},
abstract = {The regulatory effects of salinity and inorganic nitrogen compounds on nitriflcation and denitrification were studied in intertidal sandy sediments and rocky biofilms in the Douro River estuary, Portugal, over a 12-month period. Nitrification and denitrification rates were measured in slurries of field samples and enrichment experiments using the difiuoromethane and the acetylene inhibition techniques, respectively. Salinity did not regulate denitrification in either environment, suggesting that halotolerant bacteria dominated the denitrifier communities. However, nitrification rates were stimulated when salinity increased from 0 to 15 practical salinity units. NO3- addition experiments revealed that NO3- availability stimulates denitrification rates in sandy sediments, but not in rocky biofilms; however, in rocky biofilms a positive and linear relationship was observed between denitrification rates and water column NO3- concentrations (r = 0.92) during the monthly surveys. The N2O:N2 ratios increased rapidly when NO3- increased from 63 to 363 uM; however, results from monthly surveys showed that environmental parameters other than NO3- availability may be important in controlling the variation in N2O production via denitrification. Ammonium additions to sandy sediments stimulated nitrification rates by 35\% for the 20 uM NH4+ addition, but NH4+ appeared to inhibit nitrification at high concentration addition (200 uM NH4+). In contrast, rocky biofilm nitrification was stimulated by 65\% when 200 uM NH4+ was added.},
keywords = {denitrification, duoro river, estuary, GCE, inorganic nitrogen, intertidal sediments, nitrification, portugal, rocky biofilms, salinity},
author = {Magalh and Joye, Samantha B. and Moreira, R. M. and Wiebe, William J. and Bordalo, A. A.}
@article {81527,
title = {Functional- and abundance-based mechanisms explain diversity loss due to N fertilization},
volume = {102},
year = {2005},
pages = {4387-4392},
abstract = {Human activities have increased N availability dramatically in terrestrial and aquatic ecosystems. Extensive research demonstrates that local plant species diversity generally declines in response to nutrient enrichment, yet the mechanisms for this decline remain unclear. Based on an analysis of >900 species responses from 34 N-fertilization experiments across nine terrestrial ecosystems in North America, we show that both trait-neutral and trait-based mechanisms operate simultaneously to influence diversity loss as production increases. Rare species were often lost because of soil fertilization, randomly with respect to traits. The risk of species loss due to fertilization ranged from >60\% for the rarest species to 10\% for the most abundant species. Perennials, species with N-fixing symbionts, and those of native origin also experienced increased risk of local extinction after fertilization, regardless of their initial abundance. Whereas abundance was consistently important across all systems, functional mechanisms were often system-dependent. As N availability continues to increase globally, management that focuses on locally susceptible functional groups and generally susceptible rare species will be essential to maintain biodiversity.},
keywords = {diversity, fertilization, GCE, nitrogen, SEV, SGS},
url = {http://www.pnas.org/cgi/content/abstract/0408648102v1},
author = {Suding, Katherine N. and Collins, Scott L. and Gough, Laura and Clark, Christopher M. and Cleland, Elsa E and Gross, Katherine L. and Milchunas, Daniel G. and Pennings, Steven C.}
@article {69278,
title = {Functional- and abundance-based mechanisms explain diversity loss due to N fertilization},
journal = {Proceedings of the National Academy of Sciences},
volume = {102},
year = {2005},
pages = {4387-4392},
abstract = {Abstract 1918},
keywords = {CDR, GCE, KBS, NWT, SEV, SGS},
author = {Suding, K.N. and Collins, S. L. and Gough, L. and Clark, C and Cleland, E.E. and Gross, K.L. and Milchunas, DG. and Pennings, S}
@article {69298,
title = {Habitat range and phenotypic variation in salt marsh plants},
journal = {Plant Ecology},
volume = {176},
year = {2005},
pages = {263-273},
abstract = {Ecologists have long speculated that species with wider environmental ranges would have broader ranges in phenotype; however, most tests of this hypothesis have involved small numbers of species and/or closely related taxa. We related phenotypic variation in twelve salt marsh plant species from six families to variation in four environmental variables using multiple regression. Within species, plant phenotype was predictably related to environmental variation. Salinity was the most common predictor of plant traits, followed by organic content, water content and elevation. Across species, regressions of single plant trait CVs on range (2},
keywords = {GCE, genetics, patterns, phenotypic, plants, salt marsh, variation},
author = {Richards, Christina L. and Pennings, Steven C. and Donovan, Lisa A.}
@book {81531,
title = {Handbook for LTER Education, First Edition},
year = {2005},
pages = {61},
publisher = {Long Term Ecological Research Network},
organization = {Long Term Ecological Research Network},
address = {Albuquerque, NM},
abstract = {This handbook is presented as a brief guidebook for those interested in the education programs and activities of the Long Term Ecological Research (LTER) network. The handbook is not intended to be exhaustive, but simply to give the reader an overview of LTER education efforts and to share some frameworks, materials, and best practices that have been developed and tested at LTER sites. The six chapters and eight appendices provide strategies and resources from current programs to design and develop a new program, collaborate with other sites, and to provide ideas for program expansion. Each chapter contains key references related to program design, development, implementation, and evaluation. It is important to note that each LTER site is unique and often requires site-specific plans for maximizing outreach efforts; however, all sites share the overall goals of the Schoolyard LTER (SLTER) and have several common approaches. Sharing frameworks and best practices facilitates the collaborative development and testing of the Schoolyard LTER (SLTER) as a model for the integration of ecology research and education. We encourage you to spend time reading the collection of documents on the LTER webpages that are related to education. Much of the information in this chapter can be found in detail in those documents.},
keywords = {education, GCE, LTER, Schoolyard},
url = {http://schoolyard.lternet.edu/LTEREduHandbook.pdf},
author = {Bestelmeyer, S. and Dailey, S. and Elser, M. and Hembree, Patricia A. and Landis, C. and O{\textquoteright}Connell, K. and Simmons, B and Sommer, S. and Steiner, S.}
@mastersthesis {69322,
title = {The importance of benthic primary production in salt marsh carbon cycles},
year = {2005},
pages = {90},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {Benthic microalgae are a central component of shallow coastal habitats and they may account for a significant fraction of the total primary production in these ecosystems. While several factors act in concert to generate the high photosynthetic rates observed in benthic microalgae, available data suggest light is of primary importance. Nutrient availability may also be important because increasing human population in the coastal zone has led to an oversupply of nutrients to aquatic habitats, in particular estuaries. The present study focused on the effects of light and nutrients on benthic primary production at two coastal Georgia sites: the Duplin River and the Satilla River. Benthic primary production and biomass along the Duplin varied over space and time. Nutrient addition experiments led to increased primary production by benthic microalgae (indicating nutrient limitation) with the addition of nitrogen and phosphorus at Sapelo Island but not at the Satilla River site.},
keywords = {benthic, carbon cycles, GCE, primary production, salt marsh},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/LVelasquez_MS_thesis_2005.pdf},
author = {Velasquez, Liliana E.}
@article {69336,
title = {Inorganic Nitrogen Dynamics in Intertidal Rocky Biofilms and Sediments of the Douro River Estuary (Portugal)},
journal = {Estuaries},
volume = {28},
year = {2005},
pages = {592-607},
abstract = {In this study rates of oxygen, ammonium (NH4+), nitrate (NO3-), nitrite (NO2-), and nitrous oxide (N2O) fluxes, nitrogen (N) fixation, nitrification, and denitrification were compared between two intertidal sites for which there is an abundant global literature, muddy and sandy sediments, and two sites representing the rocky intertidal zone where biogeochemical processes have scarcely been investigated. In almost all sites oxygen production rates greatly exceeded oxygen consumption rates. During daylight, NH4+ and NO3- uptake rates together with ammonification could supply the different N requirements of the primary producer communities at all four sites; N assimilation by benthic or epilithic primary producers was the major process of dissolved inorganic nitrogen (DIN) removal; N fixation, nitrification, and denitrification were minor processes in the overall light DIN cycle. At night, distinct DIN cycling processes took place in the four environments, denitrification rates ranged from 9 +/- 2 to 360 +/- 30 mmol N2 m^-2 h^-1, accounting for 10},
keywords = {biofilms, douro river, dynamics, estuary, GCE, intertidal, nitrogen cycle, portugal},
author = {Magalh and Wiebe, William J. and Joye, Samantha B. and Bordalo, A. A.}
@inbook {69347,
title = {Interactions between behaviour and physical forcing in the control of horizontal transport of decapod larvae},
booktitle = {Advances in Marine Biology},
volume = {47},
year = {2005},
pages = {107-214},
publisher = {Elsevier Science, Ltd.},
organization = {Elsevier Science, Ltd.},
address = {San Diego, CA},
keywords = {behavior, decapod, GCE, horizontal transport, larvae, physical forcing},
author = {Queiroga, Henrique. and Blanton, Jackson O.},
editor = {Fuiman, Lee}
@article {69361,
title = {Inversion of inductive electromagnetic data in high induction number terrains},
journal = {Geophysics},
volume = {70},
year = {2005},
pages = {G16-G28},
abstract = {Despite the increasing use of controlled-source frequency-domain EM data to characterize shallow subsurface structures, relatively few inversion algorithms have been widely applied to data from real-world settings, particularly in high-conductivity terrains. In this study, we develop robust and convergent regularized, least-squares inversion algorithms based on both linear and nonlinear formulations of mutual dipole induction for the forward problem. A modified version of the discrepancy principle based on a priori information is implemented to select optimal smoothing parameters that simultaneously guarantee the stability and best-fit criteria. To investigate the problems of resolution and equivalence, we consider typical layered-earth models in one and two dimensions using both synthetic and observed data. Synthetic examples show that inversions based on the nonlinear forward model more accurately resolve subsurface structure, and that inversions based on the linear forward model tend to drastically underpredict high conductivities at depth. Inversions of actual field data from well-characterized sites (e.g., National Geotechnical Experimentation Site; sand-dominated coastal aquifer in the Georgia Bight) are used to test the applicability of the model to terrains with different characteristic conductivity structure. A comparison of our inversion results with existing conepenetrometer and downhole-conductivity data from these field sites demonstrates the ability of the inversions to constrain conductivity variations in practical applications.},
keywords = {electromagnetic, GCE, geophysics, inductive, inversion},
author = {Schultz, Gregory M. and Ruppel, Carolyn D.}
@article {69370,
title = {Key factors influencing the transport of white shrimp (Litopenaeus setiferus) post-larvae into the Ossabaw Sound System, Georgia, USA},
journal = {Fisheries Oceanography},
volume = {14},
year = {2005},
pages = {175-194},
abstract = {We examined conditions under which white shrimp (Litopenaeus setiferus) post-larvae enter an estuarine channel receiving high freshwater discharge and one receiving negligible discharge in the Ossabaw Sound system of Georgia, USA, during 1997 and 1998. We used surface nets to collect plankton over several 14-day periods, during which consecutive tows were made at night against the flooding current at stations in the inlet channels. During these sampling periods, additional intensive periods of around-the-clock surface and near-bottom (using a bottom sled) plankton tows were made. Data on oceanographic conditions were obtained from moored instrument arrays and shipboard sampling. We identified three key factors that influenced the densities of post-larval white shrimp in time and space within the Ossabaw inlet system. The first factor was a critical minimum temperature of coastal waters of 27},
keywords = {fisheries, GCE, oceanography, ossabaw sound, post-larvae, shrimp},
doi = {10.1111/j.1365-2419.2005.00328.x},
url = {http://www.blackwell-synergy.com/doi/full/10.1111/j.1365-2419.2005.00328.x},
author = {Wenner, E. and Knott, D. and Barans, Charles. and Wilde, S. and Blanton, Jackson O. and Amft, Julie.}
@article {69386,
title = {Latitudinal variation in palatability of salt-marsh plants: are differences constitutive?},
journal = {Ecology},
volume = {86},
year = {2005},
pages = {1571-1579},
abstract = {Biogeographic theory argues that consumer},
keywords = {chemical defenses, GCE, herbivory, latitude, salt marsh},
author = {Salgado, Cristiano S. and Pennings, Steven C.}
@article {69395,
title = {Linking biogeography and community ecology: latitudinal variation in plant-herbivore interaction strength},
journal = {Ecology},
volume = {86},
year = {2005},
pages = {2310-2319},
abstract = {Ecological interactions may vary geographically as a function of diversity, density, or per capita interaction strengths, but we know little about the relative importance of these three mechanisms. We examined variation in species richness, abundance, and interactions among leaf-chewing herbivores and the dominant salt-marsh plant Spartina alterniflora along the Atlantic Coast of the United States. High-latitude S. alterniflora plants are more palatable to herbivores than are low-latitude plants. Within this range of latitude, diversity and density of the dominant leaf-chewing consumers, snails and grasshoppers, in Spartina-dominated portions of the marsh varied little. Low-latitude plants, however, experienced much greater levels of leaf damage from consumers than did high-latitude plants. Per capita feeding rates of low-latitude snails (Littoraria irrorata) and grasshoppers (Orchelimum fidicinum) in the laboratory were greater than feeding rates of high-latitude snails (Melampus bidentatus) and grasshoppers (Conocephalus spartinae). In field experiments, low-latitude snails strongly suppressed S. alterniflora growth, but high-latitude snails had no effect on primary production. Thus, latitudinal differences in the effect of herbivores on plants (i.e., interaction strength), driven by differences in per capita effects among species, rather than differences in diversity or density, may contribute to selection for latitudinal differences in plant palatability. Because geographical differences in interaction strength can occur in the absence of differences in diversity or density, linking biogeography with community ecology will require experimental studies that explicitly measure interaction strength at multiple geographic locations.},
keywords = {GCE, grasshopper, herbivory, latitude, littoraria, melampus, orchelimum, salt marsh, spartina},
url = {http://www.esajournals.org/esaonline/?request=get-abstract\&issn=0012-9658\&volume=086\&issue=09\&page=2310},
author = {Pennings, Steven C. and Silliman, Brian R.}
@inbook {69461,
title = {Natural and constructed wetlands},
booktitle = {Encyclopedia of Hydrological Sciences},
year = {2005},
pages = {1639-1656},
publisher = {John Wiley and Sons},
organization = {John Wiley and Sons},
address = {New York},
keywords = {constructed, GCE, hydrology, wetlands},
author = {Craft, Christopher B.},
editor = {Anderson, M. G.}
@article {69522,
title = {Plant zonation in low-latitude salt marshes: disentangling the roles of flooding, salinity and competition},
journal = {Journal of Ecology},
volume = {93},
year = {2005},
pages = {159-167},
abstract = {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. Juncus did not occur naturally in the Spartina zone and performed poorly when transplanted there, irrespective of whether neighbours were present or removed, indicating that its lower limit was set by physical stress. In contrast, although Spartina occurred naturally at low densities in the Juncus zone, it performed well if transplanted there only if neighbours were removed, indicating that its upper limit was set by competition. Parallel laboratory and field manipulations of flooding, salinity and competition indicated that the lower limit of Juncus was mediated by both flooding and salinity, but not by competition. The general mechanisms producing zonation patterns of vegetation in coastal salt marshes may be universal, as suggested by previous studies, but the importance of particular factors is likely to vary geographically. In particular, salinity stress probably plays a much more important role in mediating plant zonation patterns at lower latitudes. Our results suggest that the nature of ecological interactions is likely to vary geographically because of variation in the physical environment, and this variation must be taken into account in order to successfully generalize the results of field studies across geographical scales.},
keywords = {competition, FLOODING, GCE, plant, salinity, salt marsh, zonation},
author = {Pennings, Steven C. and Grant, Mary-Bestor. and Bertness, Mark D.}
@article {69600,
title = {Screening for bacterial-fungal associations in a southeastern U.S. salt marsh using pre-established fungal monocultures},
journal = {FEMS Microbiology Ecology},
volume = {54},
year = {2005},
pages = {179-187},
abstract = {Both bacteria and fungi play critical roles in decomposition processes in many natural environments, yet only rarely have they been studied as an integrated community. We examined whether physical associations exist between individual bacterial and fungal species that co-occur on decaying smooth cordgrass, Spartina alterniflora, in a south-eastern US salt marsh. Fungal-pervaded decaying Spartina was used as "bait" for potential bacterial associates. The bundles (infiltrated with one of three dominant fungal members of the decomposer assemblage, or an autoclaved control) were placed in a salt marsh and collected biweekly for 6 weeks during the first experiment (late summer 2002), and weekly for 3 weeks during the second experiment (early summer 2003). Terminalrestriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA genes was used to track colonization by bacterial taxa in association with the established fungal species. T-RFLP analysis of 18S-to-28S internal transcribed spacer (ITS) regions was used to monitor changes in fungal communities once bundles had been placed in the field. Results from both years were nearly identical, and showed that invasion by fungi other than the bait species was slow, resulting in a virtual fungal monoculture for several weeks into the experiments. Surprisingly, bacterial communities were una.ected by the identity of the fungal bait. Regardless of the fungal species, and even in the absence of prior fungal colonization, bacterial 16S rRNA profiles were remarkably similar. These results suggest that few species-specific associations, either positive or negative, exist between bacterial and fungal members of the Spartina decomposer community during initial colonization.},
keywords = {bacteria, fungal monocultures, fungi, GCE, salt marsh},
author = {Lyons, Justine I. and Newell, S. Y. and Brown, Ryan P. and Moran, Mary Ann.}
@mastersthesis {69605,
title = {Secondary Circulation in a Sinuous Coastal Plain Estuary},
year = {2005},
school = {Georgia Institute of Technology},
address = {Atlanta, Georgia},
abstract = {Transport and mixing of momentum and salt in an estuary varies in time and space due to river discharge, changes in tidal amplitude and phase, wind stress, and lateral mixing processes. Lateral mixing commonly refers to poorly resolved, rarely quantified interaction(s) between flows induced by secondary circulation, river discharge, wind stress, and tidal forces. Modern instrumentation and better computational techniques have generated a resurgent interest in better comprehending such interactions. The intent of this dissertation is to observe, describe, parameterize, and quantifying secondary circulation using acoustic current meters in a sinuous coastal plain estuary. This endeavor is made to improve our general understanding of secondary circulation, to identify its primary driving forces, and to better parameterize key physical processes necessary for further study in current numerical models. Secondary circulation is a broad and often confusing term used to describe several mechanisms whose result is to vertically overturn the water column along the transverse axis of a channel. Most commonly, secondary circulation is generated by one or more of the following mechanisms: channel curvature, unusual bottom topography or channel geometry, planetary rotation, and/or the differential advection of density. Secondary circulation may be composed of one or more cells that can act to reduce or enhance local velocity and density gradients. A physical manifestation of secondary flow is often observed as foam or slick lines down the longitudinal axis of an estuary. Field data for this dissertation was collected in the naturally sinuous Satilla River in southeast Georgia during the spring of 1997 and during the spring and fall of 1999. A shallow coastal plain estuary, the Satilla is a typical partially-mixed estuary characterized by 2 - 2.5 meter range semidiurnal tides. It has a strong neap-to-spring axial current inequality ranging from 0.5 m s^-1 to 2.0 m s^-1 and, likewise, has strong neap-to-spring vertical salinity variations in the thalweg from 7 PSU to 2 PSU. The density structure of the Satilla River is most sensitive to variations in salinity. In the Satilla River, secondary circulation driven by channel curvature dominates the lateral momentum balance on time scales longer than the fortnightly tidal cycle. The signal of secondary circulation is modulated on the neap-to-spring cycle due to changes in the interaction of the vertical density gradient and the speed of the axial current. At neap, the vertical stratification can limit or halt the local transverse circulation. A first order inviscid balance between the lateral baroclinic gradient and centrifugal acceleration is sufficient to explain the observed modulation. Changes in freshwater discharge do not directly affect the strength and modulation of the transverse circulation, but rather, affect the location of the maximum axial and vertical salinity gradients. The balance of mechanisms responsible for the strength and location of secondary flows in the Satilla River varies with channel geometry, discharge conditions, fortnightly tidal cycle, ebb and flood tidal phase, and lateral cross-channel position. A steady-state momentum balance between the Coriolis acceleration, centrifugal acceleration, the lateral baroclinic gradient, and bottom stress is sufficient to explain the observed changes in secondary circulation on the tidal and fortnightly time scales in the Satilla River under widely different discharge conditions and in several differently curved channel reaches. The primary momentum balance at spring tide is between centrifugal acceleration and bottom stress. At neap tide, depending on local stratification and form drag, the primary momentum balance shifts from a two-way balance between centrifugal acceleration and the lateral baroclinic gradient at low drag states to a three-way balance between centrifugal acceleration, the lateral baroclinic gradient, and bottom stress at high drag states. The change in the balance of forces that drive secondary circulation in a channel cross-section varies with lateral position. In the thalweg, the dynamic balance is between the centrifugal acceleration and the lateral baroclinic pressure gradient. In the shallows and on the shoal flanks, the dynamic balance is between the centrifugal acceleration, the lateral baroclinic pressure gradient, and bottom stress. Bottom stress drives secondary circulation in the very shallow intertidal areas of the Satilla River where bathymetry changes rapidly, acting independently of tidal phase (ebb or flood). It is important to be able to understand what processes generate and limit the strength of secondary circulation in estuaries in order to predict the length of the salt intrusion, the locus of momentum transfer, and to determine the dispersion and distribution of various properties (e.g., larvae, sediment, and pollutants) in the estuarine environment.},
keywords = {coastal plain, estuary, GCE, secondary circulation, sinuous},
url = {http://etd.gatech.edu/theses/available/etd-05042005-143327/},
author = {Elston, Susan A.}
@article {69642,
title = {The southeastern continental shelf of the United States as an atmospheric CO2 source and an exporter of inorganic carbon to the ocean},
journal = {Continental Shelf Research},
volume = {25},
year = {2005},
pages = {1917-1941},
abstract = {The US southeastern continental shelf, also known as the South Atlantic Bight (SAB), is a strong source of CO2 to the atmosphere, which is in direct contrast to recent reports regarding other major continental shelves. Both spatial (cross-shelf) and seasonal variations of the CO2 system were pronounced in the SAB. Sea surface pCO2 in winter was undersaturated relative to the atmosphere, while oversaturation of pCO2 dominated the entire shelf water in all other seasons. Annually, the SAB releases CO2 to the atmosphere at an average rate of 30 g Cm^-2 (2.5 mol Cm^-2). This system also discharges dissolved inorganic carbon to the open ocean (30 g Cm^-2 yr^-1). Methods of estimating CO2 flux and DIC flux are critically evaluated and compared. A carbon mass balance model in the SAB is presented based on inorganic carbon .uxes from this study and organic carbon .uxes from literature. The carbon budget is much closer to balance by using this carbon .ux approach than by direct measurements of primary production and respiration. It is concluded that the SAB is a net heterotrophic system annually. Intensi.ed heating, elevated input of inorganic carbon from coastal salt marshes, microbial respiration of marsh-exported organic carbon and the lack of annual spring blooms all contribute to maintaining the SAB as a strong CO2 source to the atmosphere during the warm seasons. In winter, the primary factor that governs the CO2 sink in the SAB is likely the cooling process. Strong heterotrophy during warm seasons also sustains the SAB to be an exporter of inorganic carbon to the open ocean annually. The SAB shelf functions differently from the East China Sea, the North Atlantic European Shelves, and the Mid-Atlantic Bight as a source or sink of atmospheric CO2. The SAB is classified as a "marsh-dominated" shelf as compared to other shelves in terms of carbon dynamics. Further work to study carbon dynamics in coastal margins is warranted to interpret their roles in the global CO2 budget.},
keywords = {atmospheric, CO2, continental shelf, export, GCE, inorganic carbon, ocean},
author = {Wang, Zhaohui. and Cai, Wei-Jun. and Wang, Yongchen. and Ji, Hongwei.}
@article {69697,
title = {Temperature-driven decoupling of key phases of organic matter degradation in marine sediments},
journal = {Proceedings of the National Academy of Sciences (USA)},
volume = {102},
year = {2005},
pages = {17036-17040},
abstract = {The long-term burial of organic carbon in sediments results in the net accumulation of oxygen in the atmosphere, thereby mediating the redox state of the Earth{\textquoteright}s biosphere and atmosphere. Sediment microbial activity plays a major role in determining whether particulate organic carbon is recycled or buried. A diverse consortium of microorganisms that hydrolyze, ferment, and terminally oxidize organic compounds mediates anaerobic organic matter mineralization in anoxic sediments. Variable temperature regulation of the sequential processes, leading from the breakdown of complex particulate organic carbon to the production and subsequent consumption of labile, low-molecular weight, dissolved intermediates, could play a key role in controlling rates of overall organic carbon mineralization. We examined sediment organic carbon cycling in a sediment slurry and in flow through bioreactor experiments. The data show a variable temperature response of the microbial functional groups mediating organic matter mineralization in anoxic marine sediments, resulting in the temperature-driven decoupling of the production and consumption of organic intermediates. This temperature-driven decoupling leads to the accumulation of labile, low-molecular weight, dissolved organic carbon at low temperatures and low-molecular weight dissolved organic carbon limitation of terminal metabolism at higher temperatures.},
keywords = {accumulation, biogeochemistry, dissolved organic carbon, DOC, GCE, sediments, temperature},
url = {http://www.pnas.org/cgi/content/full/102/47/17036?maxtoshow=\&HITS=10\&hits=10\&RESULTFORMAT=\&fulltext=weston+\%2B+joye\&searchid=1136415104224_10182\&FIRSTINDEX=0\&journalcode=pnas},
author = {Weston, Nathaniel B. and Joye, Samantha B.}
@mastersthesis {69746,
title = {Waves, Turbulence, and Circulation in the Altamaha River Estuary, Georgia},
year = {2005},
pages = {161},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {Physical processes such as sea surface waves, turbulence, and residual circulation were studied in an estuarine environment using several observational data sets and modeling experiments in the Altamaha River Estuary, GA. The wave energy within the estuary becomes periodic in time showing wave energy during flood to high water phase of the tide and very little wave energy during ebb to low water. This periodic modulation is a direct result of enhanced depth and current-induced wave breaking that occurs at the ebb-shoaling region surrounding the Altamaha River mouth. Modeling results showed that depth-induced wave breaking is more important during the low water phase of the tide than current-induced wave breaking during the ebb phase of the tide. In this shallow environment these wave-current interactions lead to an increased bottom roughness, resulting in an enhanced bottom friction coefficient. An increase of river discharge changed the estuarine turbulence flow and density characteristics into a more ebb-dominated and stratified system. The Reynolds stress and turbulent kinetic energy (TKE) were increased due to increased river discharge. The spectral energy density of turbulent flow was deformed by surface waves and better satisfied the -5/3 slope for isotropic trublence when the wave-induced motions were removed. Buoyancy flux increased in magnitude with increased longitudinal density gradient and showed a weak energy source during flood tide and a relatively strong energy sink during ebb. A balance between production and dissipation of energy was not obtained, implying that turbulent transport of TKE is a consideration. Numerical modeling results revealed a complex depth dependence on turbulence intensity that varied with the tidal cycle and with the level of stratification. The mean flow is dominated by the semidiurnal lunar tidal component (M2) and the tidal phase showed fairly constant values in the center of the channel with strong variations in the shoaling regions. When the M2 component was removed, weak landward residual flows appeared on both slack waters, which may be a result of weak turbulent mixing and greater stratification, and strong seaward residual flow occurred during flood and ebb tides that may be attributed to strong turbulence levels.},
keywords = {altamaha river estuary, boundary layer, buoyancy flux, circulation, dissipation rate, ebb shoaling, energy propagation, estuary, GCE, residual flow, reynolds stress, semidiurnal component, shear production, surface waves, tide, turbulence, turbulent kinetic energy, volume transport, wave breaking},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/Kang_KiRyong_PhD_2005.pdf},
author = {Kang, KiRyong.}
@article {69776,
title = {Analysis of Tidal Marsh Vegetation Patterns in Two Georgia Estuaries Using Aerial Photography and GIS},
journal = {Estuaries},
volume = {27},
year = {2004},
pages = {670-683},
abstract = {Aerial photographs and GIS analysis were used to map the distribution of tidal marsh vegetation along the salinity gradients of the estuaries of the Altamaha and Satilla Rivers in coastal Georgia. Vegetation maps were constructed from 1993 USGS DOQQs, 1:77000-scale color infrared photographs taken in 1974 and 1:24000-scale black and white photographs taken in 1953. Changes between years were identified using a GIS overlay analysis. Four vegetation classifications were identified and groundtruthed with field surveys: salt marsh (areas containing primarily Spartina alterniflora); brackish marsh (S. cynosuroides and S. alterniflora), Juncus (Juncus roemerianus), and fresh marsh (Zizania aquatica, Zizaniopsis miliacae, and others). Although the inland extent of each marsh zone was further upstream in the Satilla than the Altamaha, they corresponded with the same salinities in each estuary: the division between salt and brackish marsh occurred where high tide salinities averaged 15 psu; Juncus began at 21 psu; and the division between fresh marsh and both Juncus and brackish marsh occurred at 1 psu. 23\% of the 6,786 ha of tidal marsh vegetation mapped in the Altamaha and 13\% of the 10,205 ha mapped in the Satilla remained the same between 1953 and 1993, although this does not include the area that changed in the intervening year (1974). Juncus was the dominant classification in the intermediate regions of both estuaries, and shifts between Juncus and either brackish or salt marsh constituted the primary vegetation change between 1953 and 1993 (87\% of the changes observed in the Altamaha and 95\% of those in the Satilla). This analysis suggests that the broad distribution of tidal marsh vegetation along these two estuaries is driven by salinity, but that at the local scale these are dynamic systems with a larger complex of factors affecting the frequently changing borders of vegetation patches.},
keywords = {GCE, GIS, marsh, photography, vegetation},
author = {Higinbotham, Carrie. B. and Alber, Merryl. and Chalmers, Alice G.}
@mastersthesis {69780,
title = {Applications of Island Biogeography: Plant Diversity and Soil Characteristics Among Back-Barrier Islands Near Sapelo Island, Georgia},
year = {2004},
pages = {113},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {This work reviews Georgia coastal policy with respect to the bridging of back-barrier islands (BBIs), or marsh hammocks. It characterized plant and soil composition on BBIs near Sapelo Island, Georgia. Species richness of fourteen BBIs was examined according to the theory of island biogeography. Eighty-three species were observed in 52 100 m^2 plots. Quercus virginiana and Ilex vomitoria were the dominant overstory and understory plants, respectively, in these maritime forest communities. Linear regression analyses showed that biogeographic variables contributed to ~30\% of the variance; island size and origin were important predictors of diversity. Soil analyses indicated fine sands with low nitrogen (<=2\%) and variable carbon values (1.7-48\%). Nonmetric multidimensional scaling showed differences in species composition based on plot location and soil C:N ratios that were not reflected in diversity analyses. Resource managers may use these findings to designate sensitive areas and develop policies that promote their sustainable use.},
keywords = {Back-barrier Islands, GCE, island biogeography, plant diversity, sapelo island, soil},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/Albers_Gayle_MS_2004.pdf},
author = {Albers, Gayle.}
@article {69800,
title = {The biogeochemistry of inorganic carbon and nutrients in the Pearl River estuary and the adjacent Northern South China Sea},
journal = {Continental Shelf Research},
volume = {24},
year = {2004},
pages = {1301-1319},
abstract = {The Zhu-jiang (Pearl River) estuary and its adjacent continental shelf in the Northern South China Sea (SCS) is unique in that its drainage basin is located entirely in a subtropical zone with heavy population development, and therefore represents an important regime for biogeochemical studies on how large rivers influence continental shelves. The near-zero salinity end member has high nutrient concentrations (silicate 130},
keywords = {biogeochemistry, estuary, GCE, inorganic carbon, nutrients, pearl river, south china sea},
author = {Cai, Wei-Jun. and Dai, Minhan. and Wang, Yongchen. and Zhai, Weidong. and Chen, Tao. Hung. Shuitu. and Zhang, Fan. and Chen, Zhaozhang. and Wang, Zhaohui.}
@article {69823,
title = {Carbon dioxide degassing and inorganic carbon export from a marsh dominated estuary (the Duplin River): A marsh CO2 pump},
journal = {Limnology \& Oceanography},
volume = {49},
year = {2004},
pages = {341-352},
abstract = {We investigated the seasonal changes and the interactions of the CO2 system in a marsh-dominated estuary, the Duplin River, on Sapelo Island, Georgia. Surface water pCO2, total alkalinity (TA), and total dissolved inorganic carbon (DIC) showed a pronounced seasonal progression in this system. The estuary released 256},
keywords = {carbon dioxide, CO2, degassing, estuary, GCE, marsh, pump},
author = {Wang, Zhaohui. and Cai, Wei-Jun.}
@article {69851,
title = {Comment on "Enhanced open ocean storage of CO2 from shelf sea pumping"},
journal = {Science},
volume = {306},
year = {2004},
pages = {1477c},
abstract = {In a well-designed North Sea study, Thomas et al. found that atmospheric carbon dioxide (CO2) was absorbed by continental shelf water and was eventually exported into the North Atlantic Ocean. The work confirmed preliminary observations in the same area and provided support for the continental shelf pump hypothesis. Thomas et al. then extrapolated "the CO2 uptake by the North Sea to the global scale" and inferred a net oceanic uptake of atmospheric CO2 by coastal oceans of 0.4 Pg C year^},
keywords = {CO2, GCE, shelf sea pumping, storage},
author = {Cai, Wei-Jun. and Dai, Minhan.}
@mastersthesis {69902,
title = {Determining movement patterns and habitat use of blue crabs (Callinectes sapidus rathbun) in a Georgia saltmarsh estuary with the use of ultrasonic telemetry and a geographic information system (GIS)},
year = {2004},
pages = {178},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {Estuarine habitat in Georgia is under increasing threat of degradation, which can negatively impact ecologically and commercially important species that reside there. Blue crabs (Callinectes sapidus) are the second highest valued fishery in Georgia yet little is known about their essential habitat requirements within either subtidal or intertidal areas. Ultrasonic telemetry was used to track 57 crabs, over 4 years, in the Duplin River estuary, near Sapelo Island, GA in order to assess movement patterns and habitat use. Crabs tagged with ultrasonic transmitters ranged in size from 4 to 13.3 cm CW and varied in sex and ontogenetic stage. Crab locations, substrate type, depth, and molting habitat was organized and analyzed within a geographic information system (GIS). Reproductively mature females used the greatest total area 1,052 m^2 on average over 8 days and movement was emigrational at average speeds of 657 m/day out of the estuary into the higher salinity Doboy sound. Male crabs did not, on average, use as large an area 108 m^2 on average over 7 days and movement patterns showed a high degree of meander and retention within the system. Movement speeds averaged 82 m/day. Immature female crabs were intermediate with a larger degree of meander than mature females with average movement speeds of 150 m/day, but used less total area (157 m^2 on average over 8 days). Crabs were tracked going onto and off of the flooded vegetated marsh surface and found on patches of oyster reefs located along edges of the subtidal zone indicating their habitat use. Crabs tagged with specialized molting transmitters were tracked to their molting habitat, which consisted of the vegetated marsh surface. The use of vegetated marsh edge is very important to crabs and was recoded frequently among all sexes and sixes of crabs. The adjacent marsh, therefore, is an essential part of blue crab habitat, it defines the subtidal creek habitat and provides essential habitat for molting crabs.},
keywords = {blue crabs, callinected sapidus, duplin river, essential fish habitat, estuary, GCE, georgia coast, GIS, invertebrate, molting habitat, ultrasonic telemetry},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/Wrona_Amanda_PhD_2004.pdf},
author = {Wrona, A. B.}
@article {69983,
title = {Environmental gradients and herbivore feeding preferences in coastal salt marshes},
journal = {Oecologia},
volume = {140},
year = {2004},
pages = {591-600},
abstract = {Current theories of plant-herbivore interactions suggest that plants may differ in palatability to herbivores as a function of abiotic stress; however, studies of these theories have produced mixed results. We compared the palatability of eight common salt marsh plants that occur across elevational and salinity stress gradients to six common leaf-chewing herbivores to determine patterns of plant palatability. The palatability of every plant species varied across gradients of abiotic stress in at least one comparison, and over half of the comparisons indicated significant differences in palatability. The direction of the preferences, however, was dependent on the plant and herbivore species studied, suggesting that different types of stress affect plants in different ways, that different plant species respond differently to stress, and that different herbivore species measure plant quality in different ways. Overall, 51\% of the variation in the strength of the feeding preferences could be explained by a knowledge of the strength of the stress gradient and the type of gradient, plant and herbivore studied. This suggests that the prospects are good for a more complex, conditional theory of plant stress and herbivore feeding preferences that is based on a mechanistic understanding of plant physiology and the factors underlying herbivore feeding preferences.},
keywords = {environmental stress, GCE, plant stress, plant vigor, plant-herbivore interactions, salt marsh},
author = {Goranson, Carol E. and Ho, Chuan-Kai. and Pennings, Steven C.}
@mastersthesis {69994,
title = {Evolution in closely adjacent salt marsh environments},
year = {2004},
pages = {141},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {Environmental variation and its effect on phenotypic variation have long been of interest to evolutionary ecologists. Several hypotheses suggest how plants can live across steep environmental gradients. These include clonal integration, phenotypic plasticity and genetic differentiation. The main objective of this dissertation was to determine what strategies salt marsh plants use to live across the environmental gradients of the marsh. Field surveys of plant phenotypes, environmental parameters and allozyme patterns as well as a greenhouse study and a reciprocal transplant study were conducted to meet this objective.Field surveys of 12 species indicated that plant phenotypic variation is correlated to environmental variation. In contrast, allozyme patterns showed no association between alleles or genotypes with microhabitats. Similarly, levels of diversity did not differ across microhabitats along the gradient. Much of the variation in the distribution of genetic diversity, however, was predictable based on the gradient. In addition, genetic diversity was surprisingly high and clone size was limited. In both the greenhouse and field reciprocal transplant studies there was evidence of phenotypic plasticity for all traits measured. The greenhouse study on outcrossed seedlings revealed genetic variation for only final height and concentrations of leaf elements Na, P, and Mg. Alternatively, the field experiment on clones of field collected plants, found genetic variation in almost all salt tolerance traits. In high and low salt gardens, there was significant selection for increased total leaf area and water use efficiency (WUE). However, patterns of selection were significantly different in the two gardens only for stabilizing selection on WUE.These studies suggest that salt marsh plants are highly plastic. Although there is a lot of genetic variation for salt tolerance traits, and some evidence for differentiation between the two habitats, there is little evidence that these habitats select on traits differently. Differential selection in the two habitats on WUE was the one exception, however there was no evidence of differentiation for this trait. These studies therefore reveal the importance of phenotypic plasticity as the predominant strategy for living across the environmental gradients of the salt marsh.},
keywords = {adaptation, borrichia frutescens, ecophysiology, evolution, GCE, halophytes, natural selection, phenotypic plasticity, salt marsh plants, sapelo island, spartina alterniflora},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/Richards_Christina_PhD_Jun2004.pdf},
author = {Richards, Christina L.}
@mastersthesis {70074,
title = {Impact of Fertilization on a Salt Marsh Food Web in Georgia},
year = {2004},
pages = {127},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {I examined the response of a salt marsh food web to nutrients, and spatial variation in this response, at 19 sites on the Georgia coast. In fertilized treatments, Spartina alterniflora increased at the expense of Juncus roemerianus. Spartina dominance was reduced at sites with greater upland influence, regardless of fertilization. Because fertilization changes plant quantity and quality, it could also affect consumers of plants. Fertilization positively influenced herbivores (grasshoppers), had little effect on decomposers (fungi), and no effect on detritivores (snails). The two snail species Littoraria irrorata and Melampus bidentatus were negatively correlated with each other and likely compete. Natural variation among sites was typically similar or greater than impacts of fertilization. These results suggest that eutrophication of salt marshes is likely to have stronger impacts on plants and herbivores than on decomposers and detritivores, and that impacts are not likely to be much greater than variation among sites.},
keywords = {competition, fertilization, fungi, GCE, grasshopper, juncus, salt marsh, snail, spartina},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/McFarlin_Thesis_2004.pdf},
author = {McFarlin, Caroline R.}
@mastersthesis {70138,
title = {Latitudinal variation in palatability of salt marsh plants: Constitutive or induced?},
year = {2004},
pages = {57},
school = {University of Houston},
address = {Houston, Texas},
abstract = {A central biogeographic theory argues that consumer-prey interactions are more intense, and prey defenses better developed, at lower latitudes. Along the Atlantic Coast of the United States, southern salt marsh plants are less palatable than northern conspecifics. To test the hypothesis that latitudinal variation in palatability would occur in the absence of geographically-different environmental cues (i.e., that differences in palatability are constitutive rather than induced by climate or herbivore damage), I grew high- and low-latitude individuals of three species of salt marsh plants from seeds (Solidago sempervirens) or rhizome cuttings (Distichlis spicata and Spartina alterniflora) in a common-garden greenhouse environment, and compared their palatability to herbivores over time. I also quantified leaf toughness and nitrogen content of those plants in order to help explain results of feeding assays. My results document a pattern for northeastern salt marsh plants to be more palatable than southeastern conspecifics after being germinated in a greenhouse or kept under common-garden conditions for several clonal generations, suggesting that the latitudinal variation of salt marsh plants observed in the field is constitutive rather than induced by environmental cues. Latitudinal variation in plant traits depended on the plant species. Toughness varied as a function of latitude for Spartina and Distichlis, with southern plants being tougher than northern conspecifics across clonal generations. For all generations of Spartina and for seed-propagated Solidago, northern plants had higher nitrogen content than southern plants. Results are consistent with the theory that herbivory is a strong selective pressure that might be shaping geographical variation in plant palatability. However, many other factors, such as differences in growth season length and external disturbances could be of crucial importance in mediating this latitudinal pattern of palatability. Understanding the genetic and environmental bases of intraspecific variation and how they covary on broad geographic scales can provide important clues to how organisms adapt to different and changing environments.},
keywords = {ecology, GCE, latitude, palatability, salt marsh plants},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/Salgado_MS_Thesis_Jun2004.pdf},
author = {Salgado, Cristiano S.}
@inbook {70174,
title = {Marine and estuarine mycelial Eumycota and Oomycota},
booktitle = {Biodiversity of Fungi. Inventory and Monitoring Methods},
year = {2004},
pages = {533-545},
publisher = {Elsevier Academic Press},
organization = {Elsevier Academic Press},
address = {Amsterdam},
keywords = {biodiversity, fungi, GCE, methods, oomycota, straminipila},
author = {Kohlmeyer, Jan. and Volkmann-Kohlmeyer, Brigitte. and Newell, S. Y.},
editor = {Foster, Mercedes S.}
@article {70207,
title = {Multi-Scale Genetic Analysis of Uniola Paniculata (Poaceae): A Coastal Species with a Linear, Fragmented Distribution},
journal = {American Journal of Botany},
volume = {91},
year = {2004},
pages = {1345-1351},
abstract = {Geographic and fine-scale population genetic structures of Uniola paniculata, the dominant coastal dune grass in the southeastern USA, were examined. The linear, naturally fragmented distribution of this native perennial was hypothesized to lead to high genetic structure and lower genetic diversity at the margin of the species range. The extensive ramet production and low seed germination of this species were also expected to cause populations to be dominated by a few large clones. At 20 sites throughout the range of the species, leaf tissue was collected from 48 individuals. Clonal structure was examined using leaf tissue collected from an additional 60 individuals, each in four patches at two sites. Starch gel electrophoresis was used to resolve 27 allozyme loci. The results indicated that Uniola had greater genetic structure (GST 5 0.304) than most other outcrossing species, indicating moderate barriers to gene flow. There was a weak but significant positive relationship between genetic distance and geographic distance, supporting an isolation-bydistance model of gene flow. There were no obvious disjunctions between regions. Genetic diversity (He) was relatively uniform throughout most of the range of the species but was lower in all western Gulf of Mexico populations. Clonal diversity varied both within and among sites, but clones were often small, suggesting that sexual reproduction and recruitment from seeds are important factors maintaining genetic diversity.},
keywords = {allozymes, clonal structure, coastal plants, GCE, gene flow, population genetics, sea oats, Southeastern United States, uniola paniculata},
url = {http://www.amjbot.org/cgi/content/full/91/9/1345},
author = {Franks, Steven J. and Richards, Christina L. and Gonzales, E. and Cousins, J. C. and Hamrick, James L.}
@article {70299,
title = {Redox zonation at the saline-influenced boundaries of a permeable surficial aquifer: effects of physical forcing on the biogeochemical cycling of iron and manganese},
journal = {Journal of Hydrology},
volume = {296},
year = {2004},
pages = {164-178},
abstract = {Research investigating geochemical changes accompanying subsurface mixing of fresh and saline water has primarily focused on cation exchange and mineral dissolution/precipitation reactions. In this study, we report on redox species zonation at the boundaries of a freshwater lens confined beneath a small, permeable island surrounded by saline marshes and tidal creeks and located on the estuary side of Sapelo Island, Georgia. The spatial and temporal distribution of the chemical species in the aquifer implies that the freshwater lens resists saline intrusion by maintaining constant advection across the salinity gradient. As a result, the biogeochemical processes in this aquifer seem to have reached a quasi steady-state very close to equilibrium. Redox reactions associated with natural organic matter oxidation may also play an important role at the salinity transition. Surprisingly, aerobic respiration and microbial iron reduction seem to be the main pathways for natural organic matter oxidation. Sulfate reduction is not significant despite the high concentration of sulfate available, and manganese oxides are probably chemically reduced by dissolved sulfide and Fe2+. This study is the first to demonstrate that iron and manganese reduction takes place at the salinity transitions bounding both sides of an island freshwater lens and that microbial iron reduction accounts for most of anaerobic respiration of natural organic matter at these transitions.},
keywords = {biogeochemical cycling, boundaries, GCE, iron, manganese, physical forcing, redox, surficial aquifer, zonation},
author = {Snyder, Matthew. and Taillefert, Martial. and Ruppel, Carolyn D.}
@mastersthesis {70350,
title = {Salt marsh dieback in Georgia: Field survey and transplant experiments},
year = {2004},
pages = {108},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {In winter 2002, portions of the salt marshes of coastal Georgia began experiencing dieback, affecting both Spartina alterniflora and Juncus roemerianus. During the summer of 2003, a field survey of 18 widely distributed sites along the coast was conducted to document the characteristics of and obvious patterns in dieback areas. Most dieback areas were small (<1 acre), did not show spatial patterns and occurred along the edges of tidal creeks. There were no consistent differences in soil salinity, pH or redox potential between dieback and healthy areas. A transplant study was carried out to determine if healthy plants can survive in dieback areas. Transplant survival was 100\% from May to October 2003, and growth was observed in both dieback and healthy (control) areas. The results of this study suggest that drought, along with various contributing factors, was the ultimate cause of salt marsh dieback in coastal Georgia.},
keywords = {die-back, GCE, marsh, salt marsh},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/Ogburn_Matthew_MS_2004.pdf},
author = {Ogburn, Matthew B.}
@article {70351,
title = {Salt Marsh Litter and Detritivores: A Closer Look at Redundancy},
journal = {Estuaries},
volume = {27},
year = {2004},
pages = {753},
abstract = {Most primary production of angiosperms in coastal salt marshes enters the detritivore food web; studies of this link have predominantly focused on one plant species (Spartina alterniflora) and one detritivore species (Littoraria irrorata). In mesocosm experiments, we studied the rates and pattern of decomposition of litter derived from four plant species common in southeastern United States coastal salt marshes and marsh-fringing terrestrial habitats. Crustaceans and gastropods were selected as detritivores feeding on, and affecting degradation of, the litter of two monocotyledons and two dicotyledons. Despite interspecific similarities in consumption, detritivores exhibited species-specific effects on litter chemistry and on the activity of litter-colonizing microbiota. The chemical composition of feces depended upon both the litter type and the detritivores},
keywords = {armases, detritivore, GCE, isopod, litter, littoraria, melampus, salt marsh},
author = {Zimmer, Martin. and Pennings, Steven C. and Buck, Tracy L. and Carefoot, Thomas H.}
@mastersthesis {70395,
title = {Spartina species zonation along an estuarine gradient in Georgia: Exploring mechanisms controlling distribution},
year = {2004},
pages = {206},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {The general paradigm for the observed plant zonation in salt marshes is that a combination of abiotic stress and competition drive vegetation patterns within a single marsh, but there have been few studies investigating the bankside vegetation changes that occur along the longitudinal salinity gradient of estuaries. The main objectives of the research presented in this dissertation were to examine whether the same controls that explain the distribution of Spartina alterniflora in the salt marsh can be applied without modification to a longitudinal salinity gradient and to evaluate changes in Spartina distributions under drought conditions. Reciprocal transplant studies, greenhouse experiments, species removals in mixed Spartina stands, and vegetation surveys were conducted in the estuary of the Altamaha River, GA, where S. cynosusroides occurs upstream of S. alterniflora. In reciprocal transplant experiments, each plant survived and performed best in its natural habitat. The presence of conspecific neighbors slightly reduced S. alterniflora plant performance in the salt marsh whereas S. cynosuroides showed little response in either environment. The results of these and other experiments suggest the lower estuarine distribution of Spartina cynosuroides is controlled by abiotic conditions (salinity or sulfide concentrations). The upper estuarine distribution of S. alterniflora is not well understood, but seems to also be primarily controlled by abiotic factors (possibly a sulfate requirement). These outcomes challenge results from previous investigations of zonation controls in salt marshes and suggest that modifications to the salt marsh paradigm are necessary when describing vegetation distribution along an estuarine gradient. During an extended drought (2000-2002), Spartina alterniflora density increased to a greater extent than S. cynosuroides in mixed stands and the location where Spartina cover was 50\% S. cynosuroides and 50\% S. alterniflora shifted approximately 3 km upriver, suggesting that Spartina communities can respond rapidly to increasing estuarine salinity. These studies improve our understanding of the ecological linkages in estuaries and can aid coastal policymakers in making better management decisions and predictions concerning how changes in freshwater inflow might impact the distribution of estuarine organisms.},
keywords = {distribution, estuarine gradient, GCE, plants, spartina, zonation},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/White_Susan_PhD_2004.pdf},
author = {White, Susan N.}
@mastersthesis {70439,
title = {Temporal and spatial variation in seston available to oysters and the contribution of benthic diatoms to their diet in the Duplin River, Georgia},
year = {2004},
pages = {220},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {This study examined the quantity and quality of seston available to oysters and the contribution of benthic diatoms to their diets in the Duplin River, Georgia, and how it varied over different temporal and spatial scales. Average suspended particulate material (SPM), particulate organic carbon (POC), and chlorophyll a concentrations were significantly higher at the mouth (327.6 mg L^-1, 5.0 mg L^-1, 19.9},
keywords = {benthic diatoms, diet, duplin river, GCE, georgia, oysters, seston, spatial variation, temporal variation},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/Thoresen_Merrilee_PhD_2004.pdf},
author = {Thoresen, M.}
@article {70465,
title = {Unexpectedly high clonal diversity of two salt marsh perennials across a severe environmental gradient},
journal = {Ecology Letters},
volume = {2004},
year = {2004},
pages = {1155-1162},
abstract = {In salt marsh habitats, noted for their extreme environments, a widely held assumption is that a few large clones dominate plant populations. Using a large number of polymorphic allozyme loci, we were able to test this assumption for two salt marsh plants known to span extreme salinity gradients. For both species, clonal diversity was surprisingly high across populations: Simpson},
keywords = {allozymes, borrichia frutescens, clonal structure, fine-scale differentiation, GCE, salt marsh plants, sapelo island, sea ox-eye daisy, smooth cord grass, spartina alterniflora},
author = {Richards, Christina L. and Hamrick, James L. and Donovan, Lisa A. and Mauricio, Rodney.}
@inbook {70546,
title = {Benthic microalgal production and nutrient dynamics in intertidal sediments},
booktitle = {BioGeoChemistry of Tidal Flats},
year = {2003},
pages = {67-70},
publisher = {Forschungszentrum Terramare Berichte Nr. 12, Proceedings of a Workshop held at the Hanse Institute of Advanced Study},
organization = {Forschungszentrum Terramare Berichte Nr. 12, Proceedings of a Workshop held at the Hanse Institute of Advanced Study},
address = {Delmenhorst, Germany},
keywords = {benthic, dynamics, GCE, intertidal, microalgae, nutrients, sediments},
author = {Joye, Samantha B. and Porubsky, William P. and Weston, Nathaniel B. and Lee, Rosalynn Y.},
editor = {Rullk}
@mastersthesis {70551,
title = {Biogeochemical Changes of Chemical Signals in the Georgia "Land-To-Ocean Continuum"},
year = {2003},
pages = {187},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {Major portion of this dissertation concentrated on interpreting and analyzing temporal and spatial variability of the CO2 system in the Georgia land-to-ocean continuum, which consists of Georgia marsh-influenced riverine and non-riverine estuaries and their adjacent continental shelf up to the shelf-break. Chapter 2 described an improved fiber optic pCO2 sensor based on a long pathlength liquid-core waveguide made by Teflon AF 2400. Three pronounced characteristics of the sensor are short response time, high sensitivity and long-time stability. Chapter 3 discussed the spatial and temporal variability of distributions of nitrogen nutrients in the five Georgia riverine estuaries. Estuarine nitrification and marsh denitrification are likely two major processes that modify spatial distributions of inorganic nitrogen within these estuaries. Seasonality of river discharge and temperature are apparently responsible for observed seasonal changes in distribution patterns of inorganic nitrogen. Chapter 4 examined CO2 dynamics in the South Atlantic Bight (SAB). The study found that this shelf region is a strong atmospheric CO2 source annually and an exporter of inorganic carbon to the open ocean. The carbon budget of the region indicated that the system is net heterotrophic annually. The annual CO2 source of the system to the atmosphere is likely maintained as a combined result of net heterotrophy, more intensive heating, and high discharge of inorganic carbon from coastal salt marshes. The research in Chapter 5 was centered on the seasonal variations of the CO2 system in Georgia estuary-marsh complexes. CO2 degassing and inorganic carbon export from a marsh-dominated tidal creek, the Duplin River, were quantified on a monthly basis in order to examine seasonality of marsh-estuary interaction. The study concluded that marsh export of inorganic carbon primarily supports CO2 degassing and inorganic carbon export in the marsh-dominated estuaries. Extrapolation of the Duplin River.s result to the entire SAB salt marshes indicated that marsh export of inorganic carbon likely has significant influence on the CO2 dynamics in the SAB. As a summary of carbon cycle in the Georgia "land-to-ocean continuum", a carbon mass balance and transport model and an "extended continental shelf pump" hypothesis were presented in Chapter 6.},
keywords = {biogeochemistry, CO2, continental shelf, dic, estuary, GCE, georgia, modeling, nitrogen, nutrients, signals},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/wang_zhaohui_200305_phd.pdf},
author = {Wang, Zhaohui.},
editor = {Jahnke, Richard A.}
@article {70644,
title = {Diet choice in an omnivorous salt marsh crab: different food types, claw allometry, and habitat complexity},
journal = {Journal of Experimental Marine Biology and Ecology},
volume = {292},
year = {2003},
pages = {103-116},
abstract = {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 growth experiment, an invertebrate diet supported better growth than any other single diet; however, growth also occurred on single diets of mud, leaf litter or fresh leaves. Mixed diets provided the best growth. If alternative foods were available, consumption of leaf litter and fresh leaves decreased, but these items were not dropped from the diet completely. In contrast, consumption of invertebrate prey was not affected by the availability of alternative foods. In a predation experiment, crustacean prey (an amphipod and an isopod) were more vulnerable to predation by Armases than were two small gastropod species. Only large male Armases were able to consume large numbers of gastropods. Environmental structure (plant litter or litter mimics) reduced predation rates, especially on crustaceans, which actively utilized the structure to hide from predators. Armases consumes a mixed diet because several factors (prey physical defenses, avoidance behavior of prey, growth benefits of a mixed diet) favor omnivory over a specialized diet.},
keywords = {claw allometry, complexity, crab, diet, GCE, habitat, omnivorous, salt marsh},
author = {Buck, Tracy L. and Breed, Greg A. and Pennings, Steven C. and Chase, Margo E. and Zimmer, Martin. and Carefoot, Thomas H.}
@article {70661,
title = {Diversity of ascomycete laccase gene sequences in a southeastern U.S. salt marsh},
journal = {Microbial Ecology},
volume = {45},
year = {2003},
pages = {270-281},
abstract = {The diversity of ascomycete laccase sequences was surveyed in a southeastern U.S. salt marsh using a degenerate primer set designed around copper binding sites conserved in fungal laccases. This gene was targeted for diversity analysis because of its potential function in lignin degradation in the salt marsh ecosystem and because few studies have assessed functional gene diversity in natural fungal communities. Laccase sequences were amplified from genomic DNA extracted from twenty four isolates (representing ten ascomycete species) cultured from decaying blades of Spartina alterniflora, and from DNA extracted directly from the decaying blades. Among the ascomycete isolates, twenty-one yielded a PCR product of expected size (~900 bp) that was tentatively identified as laccase based on sequence similarities to previously published laccase sequences from related organisms. Overall, thirteen distinct sequence types, containing 39 distinct sequences, were identified among the isolates, with several species yielding multiple distinct laccase types. PCR amplifications from early and late decay blades of S. alterniflora yielded seven laccase types. Of these, five were composed of sequences >96\% similar at the amino acid level to sequences from three cultured ascomycetes previously found to be dominant members of the fungal communities on decaying S. alterniflora blades. Two of the laccase types from the natural-decay clone library were novel, and did not match any of the sequences obtained from the cultured ascomycetes. The 39 distinct sequences and fifteen distinct laccase sequence types retrieved from the S. alterniflora decay system demonstrate high sequence diversity of this functional gene in a natural fungal community.},
keywords = {ascomycete, diversity, GCE, gene, genetics, salt marsh, sequence},
author = {Lyons, Justine I. and Newell, S. Y. and Buchan, Alison. and Moran, Mary Ann.}
@article {70668,
title = {Dynamics of bacterial and fungal communities on decaying salt marsh grass},
journal = {Applied and Environmental Microbiology},
volume = {69},
year = {2003},
pages = {6676-6687},
abstract = {Both bacteria and fungi play critical roles in decomposition processes in many natural environments, yet only rarely have they been studied as an integrated microbial community. Here we describe the bacterial and fungal assemblages associated with two decomposition stages of Spartina alterniflora detritus in a productive southeastern U.S. salt marsh. 16S rRNA genes and 18S-to-28S internal transcribed spacer (ITS) regions were used to target the bacterial and ascomycete fungal communities, respectively, based on DNA sequence analysis of isolates and environmental clones and by using community fingerprinting based on terminal restriction fragment length polymorphism (T-RFLP) analysis. Seven major bacterial taxa (six affiliated with the alpha-Proteobacteria and one with the Cytophagales) and four major fungal taxa were identified over five sample dates spanning 13 months. Fungal terminal restriction fragments (T-RFs) were informative at the species level; however, bacterial T-RFs frequently comprised a number of related genera. Amplicon abundances indicated that the salt marsh saprophyte communities have little-to-moderate variability spatially or with decomposition stage, but considerable variability temporally. However, the temporal variability could not be readily explained by either successional shifts or simple relationships with environmental factors. Significant correlations in abundance (both positive and negative) were found among dominant fungal and bacterial taxa that possibly indicate ecological interactions between decomposer organisms. Most associations involved one of four microbial taxa: two groups of bacteria affiliated with the alpha-Proteobacteria and two ascomycete fungi (Phaeosphaeria spartinicola and environmental isolate "4clt").},
keywords = {bacteria, decaying, decomposers, fungi, GCE, grass, microbial, salt marsh},
author = {Buchan, Alison. and Newell, S. Y. and Butler, M. and Biers, Erin J. and Hollibaugh, James T. and Moran, Mary Ann.}
@article {70784,
title = {Fungal content and activities in standing-decaying leaf blades of plants of the Georgia Coastal Ecosystems research area},
journal = {Aquatic Microbial Ecology},
volume = {32},
year = {2003},
pages = {95-103},
abstract = {Change in salinity, including expansion or contraction of salt- and freshwater marshes, due to altered river outflow may influence a variety of ecosystem processes, and the literature suggests that fungal activity in standing-decaying blades of macrophytes may be lower in freshwater marshes than in saltmarshes. I measured living-fungal mass (as ergosterol), rate of carbon-dioxide evolution, and rate of fungal membrane synthesis (acetate incorporation into ergosterol) for standing-decaying blades from a series of macrophytes, including saltmarsh cordgrass in both saline and fresher-water sites. Three terrestrial plants with prominent standing-decaying leaf blades were included for comparison. Species involved were: Spartina alterniflora, Spartina cynosuroides, Zizaniopsis miliacea, Typha angustifolia, Sabal palmetto, Uniola paniculata, and Panicum amarum. Although there was no difference in fungal content of S. alterniflora blades from saltier and fresher sites, there was a significant trend downwards (from >500 to <250},
keywords = {altamaha river, carbon-dioxide release, ergosterol, freshwater marsh, fungal biomass, fungal productivity, GCE, saltmarsh, standing decay},
author = {Newell, S. Y.}
@article {70785,
title = {Fungal farming in a snail},
journal = {Proceedings of the National Academy of Sciences},
volume = {100},
year = {2003},
pages = {15643-15648},
abstract = {Mutualisms between fungi and fungus-growing animals are model systems for studying coevolution and complex interactions between species. Fungal growing behavior has enabled cultivating animals to rise to major ecological importance, but evolution of farming symbioses is thought to be restricted to three terrestrial insect lineages. Surveys along 2,000 km of North America{\textquoteright}s Atlantic coast documented that the marine snail Littoraria irrorata grazes fungus-infected wounds on live marsh grass throughout its range. Field experiments demonstrate a facultative, farming mutualism between Littoraria and intertidal fungi. Snails graze live grass primarily not to feed but to prepare substrate for fungal growth and consume invasive fungi. Fungal removal experiments show that snails and fungi act synergistically to suppress marsh grass production. These results provide a case of fungus farming in the marine environment and outside the class Insecta and reveal a previously undemonstrated ecological mechanism (i.e., facilitation of fungal invasion) by which grazers can exert top-down control of marine plant production.},
keywords = {decay, farming, fungus, GCE, littoraria irrorata, periwinkles, snail, spartina alterniflora},
author = {Silliman, Brian R. and Newell, S. Y.}
@article {70790,
title = {The geochemistry of dissolved inorganic carbon in a surficial groundwater aquifer in North Inlet, South Carolina and the carbon fluxes to the coastal ocean},
journal = {Geochimistry Cosmochimistry Acta},
volume = {67},
year = {2003},
pages = {631-637},
abstract = {Abstract},
keywords = {aquifer, carbon fluxes, coastal ocean, dic, dissolved inorganic cargon, GCE, groundwater, north inlet, south carolina, surficial},
author = {Cai, Wei-Jun. and Wang, Yongchen. and Krest, James. and Moore, Willard S.}
@article {70792,
title = {Geographic variation in positive and negative interactions among salt marsh plants},
journal = {Ecology},
volume = {84},
year = {2003},
pages = {1527-1538},
abstract = {A pressing problem for ecologists is determining whether our understanding of communities, often developed from work at fine scales, can explain processes across broader scales. Here, we explore whether models of positive interactions developed in southern New England can be applied to geographic scales. Salt marsh plants may interact positively by ameliorating harsh physical conditions such as salinity stress. Because marsh porewater salinities are higher in low- vs. high-latitude marshes, we tested the hypothesis that positive interactions are increasingly important at low latitudes. Previous work supported this hypothesis at the regional scale: within New England, positive interactions were rare in Maine but common in Rhode Island. We conducted parallel experiments in Georgia and Alabama to determine whether similar results would be obtained in a geographic comparison. Nine species of salt marsh plants were transplanted into control plots or plots with neighboring vegetation removed, in three marsh zones, at two sites each in Georgia and Alabama. Removing neighbors increased porewater salinities; nevertheless, plants usually performed best in neighbor-removal treatments, indicating that most interactions were competitive rather than facilitative. Several mechanisms might explain these results. For widely distributed species, southern individuals may be more salt tolerant than northern conspecifics. We tested this hypothesis by comparing the salt tolerance of northern and southern conspecifics of three species in a common garden experiment. In two species, southern plants were more salt tolerant than northern conspecifics. Although this pattern may explain the rarity of facilitation in the south for some species, it cannot explain our overall results because few species were studied in both geographic regions. The most likely explanation for our results is that northern marsh floras are dominated by salt-sensitive species that are likely to be facilitated by neighbors, whereas southern marsh floras are dominated by salt-tolerant species that are unlikely to benefit substantially from neighbor amelioration of soil salinities. These results illustrate the difficulties inherent in extrapolating results from even well understood systems to different geographic locations or scales. Intraspecific adaptations and community composition are often likely to vary geographically, complicating our efforts to construct geographically robust generalities about community structure and processes.},
keywords = {GCE, geographic, interactions, negative, plants, positive, salt marsh},
author = {Pennings, Steven C. and Selig, Elizabeth R. and Houser, Letise T. and Bertness, Mark D.}
@article {70920,
title = {A long pathlength liquid-core waveguide sensor for real-time pCO2 measurements at sea},
journal = {Marine Chemistry},
volume = {84},
year = {2003},
pages = {73-84},
abstract = {An improved spectrophotometric pCO2 sensor based on a long pathlength liquid-core waveguide is described for pCO2 underway measurements. A low refractive index (RI) amorphous fluoropolymer (Teflon AF 2400) tubing, the heart of the sensor, served as both a CO2-permeable membrane equilibrator and a long pathlength liquid-core waveguide spectrophotometric cell. By using absorbance ratios at three wavelengths and carefully preparing and storing indicator solution, good reproducibility and long-term stability were achieved. The sensor behaved closely to theoretical prediction. Two pronounced features of the sensor were fast response (approximately 2 min to reach 99\% of full response) due to high permeability of the Teflon AF, and high precision (about +/- 2},
keywords = {GCE, liquid-core, PCO2, south atlantic bight, spectrophotometric, waveguide},
author = {Wang, Zhaohui. and Cai, Wei-Jun. and Wang, Yongchen. and Upchurch, Bruce L.}
@mastersthesis {70945,
title = {Microbial Interactions on Decomposing Spartina Alterniflora: Use of Fungally-Modified Leachate by Bacterial Communities in an Experimental Salt Marsh Decomposition System},
year = {2003},
pages = {144},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {Spartina alterniflora decomposition is an important route for carbon transfer to estuarine detrital food webs. The two major microbial groups of decomposers are fungi and bacteria, both studied separately in the Spartina decay system. By using flow-through microcosms, we studied how fungi affect Spartina decomposition products and how bacteria respond to the addition of these products as growth substrates. We found that fungi do not significantly alter leaf characteristics over < 40 day incubations, but fungi decrease Spartina particle removal and immobilize leached dissolved organic carbon (DOC), nitrogen, and phosphorus. Bacteria grown on these fungally-modified leachates did not respond numerically. However, bacterial operational taxonomic unit (OTU) diversity and ribotype diversity decreased with fungal influence. Leachates from fungally-modified Spartina leaves enhanced the relative proportion of alpha-Proteobacteria, the major Spartina-associated ribotype in nature. Overall, however, there was no conclusive evidence for antagonism between fungi and bacteria in the Spartina decay system.},
keywords = {bacteria, chitinase, decomposition, dgge, DOC, fungi, GCE, leachate, spartina alterniflora},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/Erin_Biers_Thesis_2003.pdf},
author = {Biers, Erin J.}
@article {70956,
title = {A modeling study of the Satilla River estuary, Georgia. II: Suspended sediment},
journal = {Estuaries},
volume = {26},
year = {2003},
pages = {670-679},
abstract = {A three-dimensional (3-D) suspended sediment model was coupled with a 3-D hydrodynamic numerical model and used to examine the spatial and temporal distribution of suspended sediments in the Satilla River estuary of Georgia. The hydrodynamic model was a modified ECOM-si model with inclusion of the flooding-drying cycle over intertidal salt marshes. The suspended sediment model consisted of a simple passive tracer equation with inclusion of sinking, resuspension, and sedimentation processes. The coupled model was driven by tidal forcing at the open boundary over the inner shelf of the South Atlantic Bight and real-time river discharge at the upstream end of the estuary, with a uniform initial distribution of total suspended sediment (TSS). The initial conditions for salinity were specified using observations taken along the estuary. The coupled model provided a reasonable simulation of both the spatial and temporal distributions of observed TSS concentration. Model-predicted TSS concentrations varied over a tidal cycle; they were highest at maximum flood and ebb tidal phases and lowest at slack tides. Model-guided process studies suggest that the spatial distribution of TSS concentration in the Satilla River estuary is controlled by a complex nonlinear physical process associated with the convergence and divergence of residual flow, a non-uniform along-estuary distribution of bottom stress, and the inertial effects of a curved shoreline.},
keywords = {estuary, GCE, modelling, satilla, sediment},
author = {Zheng, L. and Chen, C. and Alber, Merryl. and Liu, H.}
@article {71013,
title = {Phenotypic plasticity and interactions among plants},
journal = {Ecology},
volume = {84},
year = {2003},
pages = {1115-1128},
abstract = {We know a great deal about the plastic responses of plant phenotypes to the abiotic and biotic environment, but very little about the consequences of phenotypic plasticity for plant communities. In other words, we know that plant traits can vary widely for a given genotype, but we know little about the importance of trait-mediated interactions (TMI) among plants. Here, we discuss three major factors that affect the expression of phenotypic plasticity: variation in the abiotic environment, variation in the presence or identity of neighbors, and variation in herbivory. We consider how plastic responses to these factors might affect interactions among plants. Plastic responses to the abiotic environment have important consequences for conditionality in competitive effects, to the point of causing shifts from competitive to facilitative interactions. Because plants show a high degree of plasticity in response to neighbors, and even to the specific identify of neighbors, phenotypic plasticity may allow species to adjust to the composition of their communities, promoting coexistence and community diversity. Likewise, plastic responses to consumers may have various and counterintuitive consequences: induction of plant resistance, compensatory growth, and increased resource uptake may affect interactions among plants in ways that cannot be predicted simply by considering biomass lost to consumers. What little we know about TMI among plants suggests that they should not be ignored in plant community theory. Although work to date on the community consequences of phenotypic plasticity has been hampered by experimental constraints, new approaches such as manipulating phenotypes by using signals instead of actual environmental conditions and the use of transgenic plants should allow us to rapidly expand our understanding of the community consequences of plant plasticity.},
keywords = {botany, GCE, genetics, phenotype, plant},
author = {Callaway, Ragan M. and Pennings, Steven C. and Richards, Christina L.}
@article {71087,
title = {Riverine inorganic carbon flux and rate of biological uptake in the Mississippi River plume},
journal = {Geophysical Research Letters},
volume = {30},
year = {2003},
pages = {1032-1035},
abstract = {Inorganic carbon parameters were studied for the first time in the Mississippi River estuary and plume. Area-integrated biological uptake rates (1.5},
keywords = {biological uptake, carbon, flux, GCE, inorganic, mississippi river, plume, riverine},
author = {Cai, Wei-Jun.}
@article {71095,
title = {The role of marsh-dominated heterotrophic continental margins in transport of CO2 between the atmosphere, the land-sea interface and the ocean},
journal = {Geophysical Research Letters},
volume = {30},
year = {2003},
pages = {1849},
abstract = {Recent air-to-sea CO2 flux measurements at several major continental shelves suggest that shelves may act as a one-way pump and absorb atmospheric CO2 into the ocean. The U.S. South Atlantic Bight (SAB) contrasts these findings in that it acts as a source of CO2 to the atmosphere while simultaneously exporting dissolved inorganic carbon (DIC) to the open ocean. The shelf-wide heterotrophy and carbon exports in the SAB are subsidized by the export of organic carbon from the abundant intertidal marshes, which are a sink for atmospheric CO2. It is proposed here that the SAB represents a marsh-dominated heterotrophic ocean margin as opposed to river-dominated autotrophic margins. Based on this and other studies, DIC export flux from margins to the open ocean must be significant in the overall global ocean carbon budget.},
keywords = {atmosphere, CO2, GCE, heterotroupic, land-sea, margins, marsh-dominated, ocean},
author = {Cai, Wei-Jun. and Wang, Zhaohui. and Wang, Yongchen.}
@article {71201,
title = {Transport of salt and suspended sediments in a curving channel of a coastal plain estuary: Satilla River, GA},
journal = {Estuarine, Coastal and Shelf Science},
volume = {57},
year = {2003},
pages = {993-1006},
abstract = {This study describes the transport of salt and suspended sediment in a curving reach of a shallow mesotidal coastal plain estuary. Circulation data revealed a subtidal upstream bottom flow during neap tide, indicating the presence of a gravitational circulation mode throughout the channel. During spring tide, landward bottom flow weakened considerably at the upstream end of the channel and changed to seaward in the middle and downstream areas of the reach, suggesting the importance of tidal pumping. Salt flux near-bottom was landward at both ends of the channel during neap tide. At spring, however, the salt flux diverged along the bottom of the thalweg suggesting that tidal pumping caused a transfer of salt vertically and laterally into the intertidal zone. Thus, landward flux of salt is maintained even in the presence of subtidal seaward flow along the bottom at the downstream end of the channel. Landward bottom stress is greater than seaward stress, preferentially transporting suspended sediments upstream. Compared with salt, however, the weight of the suspended sediments causes less upward transfer of sediments into the intertidal zone. Flood flow carried more suspended sediments landward at the upstream end compared with the downstream end. We speculate that secondary flow in the curving channel picks up increasing amounts of suspended sediments along the sides during flood and adds them to the axial flow in the thalweg. Since the landward flow along the bottom of the thalweg weakens and even reverses during spring tide, there appears to be a complex re-circulation system for sediments re-suspended in curving channels that complicates the picture of a net transport of sediments landward.},
keywords = {channel, estuary, GCE, satilla river, sediments},
author = {Blanton, Jackson O. and Seim, Harvey E. and Alexander, Clark. R. and Amft, Julie. and Kineke, Gayle.}
@article {71273,
title = {Analysis of Internal Transcribed Spacer (ITS) Regions of rRNA Genes in Fungal Communities of a Southeastern U. S. Salt Marsh},
journal = {Microbial Ecology},
volume = {43},
year = {2002},
pages = {329-340},
abstract = {The ascomycete community colonizing decaying Spartina alterniflora blades in a southeastern U.S. salt marsh was characterized by analysis of internal transcribed spacer (ITS) regions of fungal rRNA genes. ITS sequences were amplified with ascomycete-specific primers from DNA extracted from S. alterniflora blades at two stages of decay (early and late), and were identified based on sequence analysis of a companion ascomycete culture collection. The S. alterniflora ITS libraries were dominated by clones from three species of ascomycetes: Mycosphaerella sp. 2, Phaeosphaeria spartinicola, and Phaeosphaeria halima. ITS sequences from five other less abundant ascomycete species were also found in the clone libraries, only two of which could be identified based on the culture collection, Hydropisphaera erubescens and a new species nicknamed {\textquoteright}4clt{\textquoteright}. Ascospore expulsion assays indicated dominance by the same three species as the ITS analysis, although this non-molecular approach differed from the molecular method in relative ranking of the dominant species and in characterization of minor species. Analysis of ITS amplicons from three replicate plots by terminal restriction fragment length polymorphism (T-RFLP) analysis showed significant spatial homogeneity in ascomycete community composition for both early and late stage decay. ITS sequence analysis identified morphologically cryptic subgroups for two of the three dominant salt marsh ascomycetes.},
keywords = {fungi, GCE, genetics, rrna, salt marsh},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/buchan_2002_micro_ecol.pdf},
author = {Buchan, Alison. and Newell, S. Y. and Moreta, Justine I.L. and Moran, Mary Ann.}
@inbook {71317,
title = {Biomass, growth rate, and production of filamentous fungi in plant litter},
booktitle = {Manual of Environmental Microbiology. Second Edition},
year = {2002},
pages = {390-408},
publisher = {ASM Press},
organization = {ASM Press},
address = {Washington, D.C.},
keywords = {biomass, filamentous, fungi, GCE, growth rate, litter, plant, production},
author = {Gessner, M. O. and Newell, S. Y.}
@article {71367,
title = {A comparison of residence time calculations using simple compartment models of the Altamaha River estuary, Georgia},
journal = {Estuaries},
volume = {25},
year = {2002},
pages = {1304-1317},
abstract = {The residence and flushing times of an estuary are two different concepts that are often confused. Flushing time is the time required for the freshwater inflow to equal the amount originally present in the estuary. It is specific to fresh water (or materials dissolved in it) and represents the transit time through the entire system (e.g. from head of tide to the mouth). Residence time is the average time particles take to escape the estuary. It can be calculated for any type of material (including fresh water), and will vary depending on the starting location of the material. In the literature, the term residence time is often used to refer to the average freshwater transit time and is calculated as such. We explored these two mixing time scales in the context of the Altamaha River Estuary, Georgia, and present a comparison of techniques for their calculation (fraction of fresh water models and variations of box models). Segmented tidal prism models, another common approach, have data requirements similar to other models but can be cumbersome to implement properly. Freshwater transit time estimates from simple steady-state box models were virtually identical to flushing times for four river-flow cases, as long as boxes were scaled appropriately to river flow, and residence time estimates from box models were also in good agreement. Mixing time estimates from box models were incorrect when boxes were improperly scaled. Mixing time scales vary nonlinearly with river flow, so characterizing the range as well as the mean or median is important for a thorough understanding of the potential for within-estuary processing. We are now developing an improved box model that will allow the calculation of a variety of mixing time scales using simulations with daily variable river discharge.},
keywords = {altamaha, discharge, estuary, flow, GCE, model, residence time},
author = {Sheldon, Joan E. and Alber, Merryl.}
@article {71379,
title = {A Conceptual Model of Estuarine Freshwater Inflow Management},
journal = {Estuaries},
volume = {25},
year = {2002},
pages = {1246-1261},
abstract = {As humans continue to influence the quantity, timing, and quality of freshwater input to estuaries, an increasing number of places are working to set minimum inflow requirements for their systems. This paper puts forth a conceptual model that explores the roles that science, management, and society play when it comes to setting inflow policy. The premise is straightforward: freshwater inflow affects estuarine conditions, which in turn impacts estuarine resources. The scientist works to quantify the relationships among these components and to understand their causative mechanisms, and policies in different estuaries have been set based on the response of one or another of these components to changes in inflow. However, it is important to recognize the influence of both society and management on this process. Whereas an estuarine scientist might identify an indicator species as an estuarine resource and work to establish the link between salinity and its distribution, 1) this specific species will not necessarily have broad general appeal as a resource to society, and 2) a manager cannot directly change its distribution. Society generally acts to protect those estuarine resources and functions that have been identified as "valued" by a broad coalition of stakeholders. The management options available to protect these resources, however, are almost invariably restricted to factors that directly affect inflow (e.g. evaluating withdrawal applications, establishing release schedules for dams) because this is where humans have control over the process. This conceptual model is used to provide an overview of the impacts of decreases in freshwater inflow to estuaries, and to explore the inflow-based, condition-based, and resource-based approaches that have been taken in several systems to establish estuarine inflow requirements.},
keywords = {estuary, GCE, management, policy},
author = {Alber, Merryl.}
@article {71384,
title = {Constraints on hydraulic parameters and implications for groundwater flux across the upland-estuary interface},
journal = {Journal of Hydrology},
volume = {260},
year = {2002},
pages = {255-269},
abstract = {Analyses of independent laboratory- and field-scale measurements from two sites on Sapelo Island, Georgia reveal heterogeneity in hydraulic parameters across the upland},
keywords = {GCE, ground water, hydrology, marsh},
author = {Schultz, Gregory M. and Ruppel, Carolyn D.}
@inbook {71405,
title = {Denitrification in the Marine Environment},
booktitle = {Encyclopedia of Environmental Microbiology},
year = {2002},
publisher = {John Wiley \& Sons, Inc.},
organization = {John Wiley \& Sons, Inc.},
address = {New York},
keywords = {GCE},
author = {Joye, Samantha B.},
editor = {Collins, G.}
@article {71420,
title = {Direct stress measurements in a shallow, sinuous estuary},
journal = {Continental Shelf Research},
volume = {22},
year = {2002},
pages = {1565-1578},
abstract = {Observations from a 4 element mooring array collected in a bend of a shallow, sinuous estuary are used to describe the flow, density structure and momentum balance over a 10-day period. In general, the flow in the lower 3 m is stratified on ebb and unstratified on flood and shear is concentrated near the bed on flood and nearly uniform throughout the water column on ebb. At spring tides stratification is reduced and the flows 1 m above bottom (mab) are consistently greatest at the downstream end of the bend. The along-channel density gradient is weakest during spring tides owing to zero gradient over most of ebb flow. At neap tides vertical stratification is strong enough to raise the gradient Richardson number well above 0.25 for most of the ebb tide. Currents are weaker and do not display a regular along-channel pattern. The variation in density and current structure is interpreted to result from variations in crosschannel circulation associated with the channel bend. At spring tides, the cross-channel circulation appears to be strong enough to overturn the water column whereas at neap tides stratification is strong enough to halt the overturning. Reynolds stress measured with a Benthic Acoustic Stress Sensor undergoes a four-fold increase between neap and spring tide. The drag coefficient relative to flow at 1 mab is 0.0015},
keywords = {estuary, GCE, physical oceanography, shallow, sinuous, stress},
author = {Seim, Harvey E. and Blanton, Jackson O. and Gross, Thomas.}
@mastersthesis {71431,
title = {Diversity of laccase gene sequences and contributions of bacteria and ascomycetous fungi to lignocellulose degradation in a southeastern U.S. salt marsh},
year = {2002},
pages = {64},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {In the first part of this study, we used molecular tools to create a database of protein sequences for laccase genes of salt marsh ascomycetes. Laccase is one of the enzymes shown to be involved in fungally-mediated lignin degradation. We then used this database to identify laccase sequences in the natural decomposer community on blades of Spartina alterniflora in two stages of decomposition. The sequences we collected contribute significantly to the relatively limited database of ascomycete sequences that currently exists. The second part of this study addressed the relative activity levels of bacterial and fungal decomposers by measuring rates of lignocellulose degradation in a simple microcosm system. The results of this study provide a tool for future evaluation of the effects of genetic manipulations on ecologically relevant decomposer organisms, including studies of gene function and degradative efficiency and interactions between bacterial and fungal decomposers.},
keywords = {ascomycetes, bacteria, degradataion, fungi, GCE, genetics, laccase, lignocellulose, salt marsh, sequences},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/Moreta_Justine_MS_thesis_2002.pdf},
author = {Moreta, Justine I.L.}
@inbook {71542,
title = {Fungi in marine/estuarine waters},
booktitle = {The Encyclopedia of Environmental Microbiology},
year = {2002},
pages = {1394-1400},
publisher = {Wiley, New York},
organization = {Wiley, New York},
keywords = {GCE},
author = {Newell, S. Y.},
editor = {Bitton, G.}
@mastersthesis {71546,
title = {Geochemical trends associated with the seawater-freshwater mixing zone in a surficial coastal aquifer, Sapelo Island, GA},
year = {2002},
pages = {149},
school = {Georgia Institute of Technology},
address = {Atlanta, Georgia},
keywords = {GCE, geochemistry, hydrology, mixing zone, sapelo island, surficial aquifer},
author = {Snyder, Matthew.}
@mastersthesis {71576,
title = {Hydrologic and Geophysical Characterization of Spatial and Temporal Variations in Coastal Aquifer Systems},
year = {2002},
pages = {329},
school = {Georgia Institute of Technology},
address = {Atlanta, Georgia},
keywords = {aquifer, coastal, GCE, geophysics, hydrology, spatial variation, temporal variation},
author = {Schultz, Gregory M.}
@article {71706,
title = {Nutrient effects on the composition of salt marsh plant communities along the southern Atlantic and Gulf Coasts of the United States},
journal = {Estuaries},
volume = {25},
year = {2002},
pages = {1164-1173},
abstract = {Nutrient availability is known to mediate plant community structure in many systems, but relatively few studies of nutrient effects have been done in systems where strong gradients in physical stress might constrain the effects of nutrients. Recent studies in New England, United States, salt marshes indicate that nutrients may strongly mediate plant community composition by increasing the competitive ability of stress-tolerant species that are normally displaced by competition to recently-disturbed or low-intertidal habitats. It is unknown whether these results can be generalized to salt marshes in other geographic regions that experience different climates, tidal regimes, and edaphic conditions. To address the generality of these results from New England, we fertilized seven different mixtures of salt marsh plants at study sites on the southeast and Gulf coasts of the U.S. Two of these mixtures were studied in both geographic regions. Consistent with results from New England, fertilization always increased the biomass of the low-marsh dominant Spartina alterniflora and usually led to it increasing in dominance at the expense of high-marsh species. Fertilization also led to increased community dominance by Distichlis, but only in a mixture where it was already common. Fertilization led to changes in plant dominance patterns in four of the seven types of mixtures that we studied. Results were not a function of edaphic conditions, at least within the range included in our study, and were consistent between the southeastern and Gulf coasts, which experience markedly different tidal regimes. The broad similarity of these results suggests that changes in nutrient input may lead to predictable changes in the composition of similar salt marsh plant communities across large geographic areas despite site to site variation in the abiotic environment.},
keywords = {communities, fertilization, GCE, nutrient, plants, salt marsh},
author = {Pennings, Steven C. and Stanton, L. E. and Brewer, J. S.}
@article {71722,
title = {Parasitic plants: parallels and contrasts with herbivores},
journal = {Oecologia},
volume = {131},
year = {2002},
pages = {479-489},
abstract = {Parasitic plants are common in natural communities, but are largely ignored in plant community theory. Interactions between parasitic plants and hosts often parallel those between herbivores and plants: both types of consumers display host preferences, reduce host biomass and alter host allocation patterns, modify plant community structure and dynamics, and mediate interactions between host plants and other organisms. In other cases, basic differences in mobility, hormonal and elemental composition and resource capture between plants and animals lead to different effects: parasitic plants have broad host ranges, affect and are affected by host plant physiology because of similar hormonal pathways between parasite and host, do not alter nutrient cycling as extensively as do herbivores, and may simultaneously parasitize and compete with hosts. Many fundamental aspects of the ecology of parasitic plants remain poorly studied, and research to date has been dominated by laboratory studies and studies of crop pests, rather than by studies of natural communities.},
keywords = {GCE, parasite, parasite-host interactions, parasitic plant, plant community, plant-herbivore interactions},
author = {Pennings, Steven C. and Callaway, Ragan M.}
@article {71882,
title = {Species-specific patterns of litter processing by terrestrial isopods (Isopoda: Oniscidea) in high intertidal salt marshes and coastal forests},
journal = {Functional Ecology},
volume = {16},
year = {2002},
pages = {596-607},
abstract = {The species-specificity of litter processing by three species of isopods at the interface between salt marsh and coastal forest habitats in the south-eastern United States was examined. To quantify isopod performance, measurements were taken of feeding, digestion and growth of isopods fed on three litter types (Juncus roemerianus, Quercus virginiana and Pinus palustris) and on artificial diets containing one of three classes of model phenolic compounds (simple phenolics and hydrolysable and condensed tannins). To quantify the ecosystem impact of isopods, promotion of microbial respiration, changes in detritus chemistry, and the quantity of litter processed by isopod populations were measured. The results support three hypotheses concerning isopod},
keywords = {biodiversity, decomposition, digestion, GCE, microbial respiration, phenolics},
author = {Zimmer, Martin. and Pennings, Steven C. and Buck, Tracy L. and Carefoot, Thomas H.}
@article {71912,
title = {Thermal evidence of water exchange through a coastal aquifer: implications for nutrient fluxes},
journal = {Geophysical Research Letters},
volume = {29},
year = {2002},
pages = {1704},
abstract = {We report the discovery of a semi-confined, high permeability zone (HPZ) 2 meters below the sea bed where exchanges between coastal aquifers and the ocean occur. A temperature probe placed in the HPZ recorded a 1},
keywords = {aquifer, fluxes, GCE, nutrient, thermal, water exchange},
doi = {10.1029/2002GL014923},
author = {Moore, Willard S. and Krest, James. and Taylor, Glenn. and Roggenstein, Edward. and Joye, Samantha B. and Lee, Rosalynn Y.}
@article {71916,
title = {Tidal current asymmetry in shallow estuaries and tidal creeks},
journal = {Continental Shelf Research},
volume = {22},
year = {2002},
pages = {1731-1743},
abstract = {We examine tidal asymmetry in a 100-km long coastal plain estuary, a 15-km long tidal creek closed at the end, and a small side channel of a coastal plain estuary closed at low water. Current meter and water depth data were harmonically analyzed for M2 and the M4 and M6 overtide. The results are displayed in a plot of tidal current versus water level and the effects of the M2, M2+M4, and M2+M4+M6 are compared in order to show how overtides affect tidal asymmetry in the different systems. The long estuary showed a gradual increase in tidal current asymmetry. The current takes on a more progressive nature as it goes into the estuary, as indicated by increasing lags between high or low water and the corresponding slack water. On the other hand, the tidal creek has its reflection point at the head, a relatively short distance from the observations, which reflects the incident tidal wave more efficiently. The tidal creek has a high salt marsh which is covered only an hour or so before high water. Since its intertidal areas flood and drain near the time of high water, maximum flood and ebb currents occur a short time before and after high water slack throughout the tidal creek. Most of the tidal energy is dissipated at the end of the creek where M6/M2 of the tidal current almost doubles. The small side channel has tidal flats that become covered soon after the time of low water. The relative time of maximum flood and ebb currents occurs much closer to the time of low-water-slack, which contrasts significantly to the timing in the tidal creek channel surrounded by high salt marsh.},
keywords = {asymmetry, creeks, current, estuary, GCE, tide},
author = {Blanton, Jackson O. and Lin, Guoqing. and Elston, Susan A.}
@mastersthesis {71993,
title = {Analysis of historic vegetation changes in two Georgia estuaries using aerial photography and GIS},
year = {2001},
pages = {93},
school = {University of Georgia},
address = {Athens, Georgia},
keywords = {aerial photography, estuaries, GCE, GIS, historic, vegetation},
author = {Smith, Carrie Beth.}
@article {72122,
title = {Distortion of tidal currents and the lateral transfer of salt in a shallow coastal plain estuary},
journal = {Estuaries},
volume = {24},
year = {2001},
pages = {467-480},
abstract = {We describe the tidal circulation of a coastal plain estuary across a flood tide delta located at its entrance. The area connects the downstream portion of the main estuary extending 30-40km inland to the more complex delta reach that consists of a shallow main channel and a series of smaller side channels. The delta acts as a frictionally dominated zone that modifies the tidal wave from a simple sinusoid to one with ebb currents that accelerate to maximum early in the tidal cycle and last more than one-half of the tidal cycle. Along smaller side channels, the tidal currents favor stronger flood or ebb currents, depending upon the local surrounding morphology. The phase difference between ebb currents in the small channels relative to those in the main channel cause some of the salt to be retained thus reducing the tendency of freshwater discharge to flush salt out of the system. This mechanism of retention differs from the selective withdrawal mechanism described for this estuary in Blanton et al. (2000).},
keywords = {circulation, estuary, GCE, physical oceanography, salt, tide},
author = {Blanton, Jackson O. and Andrade, Francisco A.}
@mastersthesis {72146,
title = {Ecology and genetics of aromatic compound degradation in the ecologically important Roseobacter lineage of marine bacteria},
year = {2001},
pages = {152},
school = {University of Georgia},
address = {Athens, Georgia},
abstract = {The degradation of lignin-related aromatic compounds is an important ecological process in the highly productive salt marshes of the southeastern U. S., yet little is known of the mediating organisms or their catabolic pathways. An initial study of six isolates suggested that members of the roseobacter lineage, a dominant marine clade within the},
keywords = {aromatic compound degradation, bacteria, dioxygenase, GCE, marine bacteria, microbial ecology, proteoatechuate, roseobacter},
url = {http://gce-lter.marsci.uga.edu/public/files/pubs/Buchan_Alison_PhD_2001.pdf},
author = {Buchan, Alison.}
@article {72252,
title = {Fungal biomass and productivity in standing-decaying leaves of black needlerush},
journal = {Marine and Freshwater Research},
volume = {52},
year = {2001},
pages = {249-255},
abstract = {Ascomycetous fungal decomposers generate the major part of the microbial biomass on and in standing naturally decaying shoots for one (smooth cordgrass, Spartina alterniflora) of the two major ramet-forming marsh plants of the south-eastern USA. Evidence from frequency of occurrence of sexual structures (ascomata) in the second major ramet-forming marsh plant (black needlerush, Juncus roemerianus) suggests that fungi are major secondary producers in the needlerush decomposition system also. To test this, samples of needlerush blades at three stages of decay were collected seasonally for three years. Average living-fungal standing crop (as ergosterol) of needlerush blades (254 ug g^},
keywords = {decay, decomposition, degradation, fungus, GCE, marsh, phycology, sapelo},
author = {Newell, S. Y.}
@article {72410,
title = {Multiyear patterns of fungal biomass dynamics and productivity within naturally decaying smooth-cordgrass shoots},
journal = {Limnology \& Oceanography},
volume = {46},
year = {2001},
pages = {573-583},
abstract = {Ascomycetous fungi are predominant secondary microbial producers of the smooth cordgrass (Spartina alterni-flora) shoot decay system. A 3-yr examination of concentrations of living fungal mass (as ergosterol content) in naturally decaying cordgrass, and of instantaneous rates of cordgrass},
keywords = {ascomycetes, fungi, GCE, marshgrass, microbial biomass, microbial productivity, saltmarsh, snail grazing},
url = {http://www.aslo.org/lo/toc/vol_46/issue_3/0573.pdf},
author = {Newell, S. Y.}
@article {72563,
title = {Soil organic carbon, nitrogen and phosphorus as indicators of recovery in restored Spartina marshes},
journal = {Ecological Restoration},
volume = {19},
year = {2001},
pages = {87-91},
abstract = {Scientists frequently measure soil properties, such as organic matter, nutrient content and particle size (sand, silt, clay), to gauge the development of functional equivalence in terrestrial and wetland restoration projects (Dancer and others, 1977; Marrs and others, 1981, Craft and others, 1988, 1999; Langis and others, 1991; Li and Daniels, 1994, Daniels and Zipper, 1995; Bishel-Machung and others, 1996; Piehler and others, 1998). Organic matter and nitrogen content are especially useful because they serve as indicators of energy flow (carbon) and nutrient (nitrogen) cycles. Because many ecosystems are nitrogen limited, ecosystem development during primary succession or succession on created, restored, or rehabilitated sites depends on accumulation of nitrogen in the soil and plant biomass (Marrs and others, 1981). In detritus-based ecosystems, such as forests and wetlands, soil organic matter supports secondary production by contributing detritus to hetertrophic organisms (Craft and others, 1999) and labile carbon (C) to fuel microbial processes like denitrification (Thompson and others, 1995) and nitrogen (N) fixation (Piehler and others, 1998).},
keywords = {GCE, marsh, nitrogen, nutrients, organic, phosphorus, plant ecology, soil, spartina},
author = {Craft, Christopher B.}
@article {72574,
title = {Spore-expulsion rates and extents of blade occupation by ascomycetes of the smooth-cordgrass standing-decay system},
journal = {Botanica Marina},
volume = {44},
year = {2001},
pages = {277-285},
abstract = {Species of ascomycetes are the principal microbial secondary producers in standing-decaying shoots of smooth cordgrass (Spartina alterniflora), the foremost and highly productive grass of saltmarshes of the eastern USA. Rates of expulsion of ascospores from wet, standing-decaying leaves of S. alterniflora were measured in spore-capture chambers seasonally, over a 3-year period. Extents of occupation of decaying leaves were determined by measuring sizes of characteristic patches associated with different species or species groups. Patches of leaf blades not occupied by at least one of the ascomycetes of the smooth-cordgrass ascomycete community occupied less than 0.2\% of leaf abaxial area. Patches of the {\textquoteright}black-peppered{\textquoteright} appearance (containing ascomata of one or more of the following: Phaeosphaeria spartinicola, Mycosphaerella sp. 2, Phaeosphaeria halima) occupied 91 to 98\% of abaxial leaf area for mid-shoot blades at subsites containing tall and intermediate-height shoots. At short-shoot sites, {\textquoteright}peppered{\textquoteright} patches occupied 53\% of leaf area, due to higher levels of periwinkle grazing at short-shoot sites; size of {\textquoteright}peppered{\textquoteright} patches was negatively correlated with extent of severe invertebrate grazing of leaves (r = -0.87). Blackened patches (containing ascomata of Buergenerula spartinae) had an overall average occupation percentage of 17\% of leaf area, and the percentage was not significantly affected by periwinkle grazing (r = -0.13). Attached decaying leaf blades low on shoots and leaf sheaths expelled few spores (< 30\% of the average for mid-shoot and upper-shoot blades), and for sheaths, B. spartinae was apparently the principal ascomycete releasing spores. For mid-shoot and uppershoot decaying blades, mean total ascospore-expulsion rate ranged from 14 to 131 spores mm^-2 leaf abaxial surface (72 h)^-1, depending on marsh watershed and season. Higher percentages of expelled ascospores for Phaeosphaeria spartinicola were found for autumn and winter (52 to 62\% of spores), but for Mycosphaerella sp. 2, peak seasons were summer and spring (42 to 54\% of spores). Percentages of ascospores for these two species were uniform over years, marsh watersheds, and tall- to short-shoot marsh subsites, whereas Phaeosphaeria halima exhibited a high degree of spatiotemporal patchiness. Because the ascospore-capture method used does not measure total ascospore release, only minimum values could be calculated for ascospore output m^-2 marsh. Calculated minimum rates of total ascospore expulsion for mid-shoot plus upper-shoot blades were 1.3 million spores m^-2 marsh h^-1 of blade wetness, 5.9 billion spores m^-2 marsh yr^-1, and 7.5 g organic mass m^-2 yr^-1, amounting to 4.5\% of total annual fungal production within these blades.},
keywords = {ascomycete, decay, decomposition, degradation, fungus, GCE, marsh, spartina alterniflora},
author = {Newell, S. Y.}
@article {72814,
title = {Effect of a broad shallow sill on the tidal circulation and salt transport in the entrance to a coastal plain estuary (Mira - Vila Nova de Milfontes, Portugal)},
journal = {Estuaries},
volume = {23},
year = {2000},
pages = {293-304},
abstract = {The dynamics of tidal intrusion fronts across sills and selective withdrawal (aspiration) in deeper channels control the exchange of seawater with the estuary. During neap tide and strong vertical stratification, flooding seawater plunges beneath less dense estuarine water somewhere on the sill. Turbulence on the sill in the intruding bottom layer promotes entrainment of fluid from the surface layer, and seawater along the sill bottom is diluted with estuarine water. Ebb flow effectively traps high salinity landward of the sill in a stagnant zone between the aspiration depth and the bottom, where it can be advected farther upstream by subsequent flood currents. During spring tide, the plunge point moves landward and off the sill, stratification is weakened in the deep channel, and aspiration during ebb extends to the bottom. This prevents the formation of stagnant water near the bottom, and the estuary is flooded with high salinity water far inland. The neap-spring cycle of tidal intrusion fronts on flood coupled with aspiration during ebb interacts with sills at the entrances of estuaries to play an important role in the transport and retention of salt within the estuary.},
keywords = {estuaries with sills, GCE, salinity, selective withdrawal, tidal circulation},
author = {Blanton, Jackson O. and Andrade, Francisco A. and Ferreira, M.A.}
@article {72985,
title = {Intertidal marsh as a source of dissolved inorganic carbon and a sink of nitrate in the Satilla River-estuarine complex in the southeastern U.S.},
journal = {Limnology \& Oceanography},
volume = {45},
year = {2000},
pages = {1743-1752},
abstract = {Total dissolved inorganic carbon (DIC), total alkalinity (TA), pH, and nitrate + nitrite (NOx) data collected during the summer of 1996 in the Satilla River estuary in the southeastern U.S. were used to assess fluxes of DIC and NOx between intertidal marshes and estuarine waters and to model system NOx dynamics. Nitrate and nitrite are produced in the low-salinity portion of the estuary. The intertidal marshes are sites of intensive respiration that export DIC to the estuary and remove NOx. An integrated view is presented on the nitrification and denitrification processes in the marsh/estuarine complex and their relationship to CO2 generation rates. The distribution of NOx in the marsh and estuarine waters indicates that all NOx generated in the marsh},
keywords = {alkalinity, denitrification, dic, flux, GCE, nitrate, nitrification, ph, satilla},
author = {Cai, Wei-Jun. and Wiebe, William J. and Wang, Yongchen. and Sheldon, Joan E.}