water column. Upward-conveyor species, like polychaete worms, are efficient at moving contaminated particles to the surface. Invasive animals can remobilize contaminants previously considered to be buried at a safe depth. In the Baltic Sea, the invasive Marenzelleria species of polychaete worms can burrow to 35-50 centimeters which is deeper than native animals, thereby releasing previously sequestered contaminants. However, bioturbating animals that live in the sediment (infauna) can also reduce the flux of contaminants to the water column by burying hydrophobic organic contaminants into the sediment. Burial of uncontaminated particles by bioturbating organisms provides more absorptive surfaces to sequester chemical pollutants in the sediments. Terrestrial Plants and animals utilize soil for food and shelter, disturbing the upper soil layers and transporting chemically weathered rock called saprolite from the lower soil depths to the surface. Terrestrial bioturbation is important in soil production, burial, organic matter content, and downslope transport. Tree roots are sources of soil organic matter, with root growth and stump decay also contributing to soil transport and mixing. Death and decay of tree roots first delivers organic matter to the soil and then creates voids, decreasing soil density. Tree uprooting causes considerable soil displacement by producing mounds, mixing the soil, or inverting vertical sections of soil. Burrowing animals, such as earth worms and small mammals form passageways for air and water transport which changes the soil properties, such as the vertical particle-size distribution, soil porosity, and nutrient content. Invertebrates that burrow and consume plant detritus help produce an organic-rich topsoil known as the soil biomantle, and thus contribute to the formation of soil horizons. Small mammals such as pocket gophers also play an important role in the production of soil, possibly with an equal magnitude to abiotic processes. Pocket gophers form above-ground mounds, which moves soil from the lower soil horizons to the surface, exposing minimally weathered rock to surface erosion processes, speeding soil formation. Pocket gophers are thought to play an important role in the downslope transport of soil, as the soil that forms their mounds is more susceptible to erosion and subsequent transport. Similar to tree root effects, the construction of burrows-even when backfilled- decreases soil density. The formation of surface mounds also buries surface vegetation, creating nutrient hotspots when the vegetation decomposes, increasing soil organic matter. Due to the high metabolic demands of their burrow-excavating subterranean lifestyle, pocket gophers must consume large amounts of plant material. Though