Relationship between land use classification and grass shrimp Palaemonetes spp. population metrics in coastal watersheds.

Estuaries in the southeastern USA have experienced increased loading of contaminants from nonpoint source runoff as well as changes in habitat (e.g., loss of wetlands) due to urbanization. These changes may pose significant risks to estuarine fauna, including crustaceans. Several studies have shown relationships between land use classification and levels of stress in estuarine populations. The grass shrimp of the genus Palaemonetes is one of the dominant species found in estuarine tidal creeks, accounting for more than 50 % of all macropelagic fauna. Grass shrimp populations were sampled monthly for 3 years at six estuarine creeks on Kiawah Island, SC. Creek watersheds were estimated using National Aerial Photograph Program color infrared and low-altitude true color aerial photography combined with in situ differentially corrected global positioning system mapping of engineered features. Land classifications delineated included water, marsh, buildings, roads, and lawns. Pairwise comparisons for grass shrimp densities among sites showed significant differences on an annual and seasonal basis. Significant relationships (p < 0.05) between land class variables and grass shrimp density were identified both annually and seasonally. These findings suggest an influence of land use on Palaemonetes spp. populations.

Long Term Monitoring of Grass Shrimp Palaemonetes spp. Population Metrics at Sites with Agricultural Runoff Influences.

Rising concern over pesticide usage near estuarine systems and evidence of physical and physiological impacts on estuarine organisms have strengthened the need to better identify the ecological effects of nonpoint source runoff. Grass shrimp, Palaemonetes spp., are ecologically important and abundant marsh inhabitants that may be impacted by anthropogenic contamination. Populations of grass shrimp were sampled monthly, over a period of ten years, at four sites in South Carolina with varying upland land use characteristics. Spatial and temporal trends in grass shrimp densities were noted over time and between sites. Agricultural and golf course land usage corresponded with decreased grass shrimp population levels, overall shrimp size, and percentage of gravid females. Conservation methods, such as the use of best management practices (BMPs) and integrated pesticide management (IPM) at agricultural fields, corresponded with increased grass shrimp population density.