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NUTRIENT AND HABITAT INDICATORS FOR CRITERIA DEVELOPMENT IN GREAT LAKES COASTAL WETLANDS
Citation:
Trebitz, A S., J. C. Brazner, J A. Morrice, M E. Sierszen, D K. Tanner, AND J A. Thompson. NUTRIENT AND HABITAT INDICATORS FOR CRITERIA DEVELOPMENT IN GREAT LAKES COASTAL WETLANDS. Presented at Wisconsin Wetlands Association Meeting, Green Bay, WI, January 26-27, 2005.
Description:
EPA's Mid-Continent Ecology Division is testing indicators and establishing stressor - response relationships to support development of nutrient and habitat criteria for Great Lakes coastal wetlands. Our focus is on water quality changes, food web shifts, and vegetation loss as nutrient endpoints and fish composition and biodiversity as habitat endpoints. Outputs from our research will include metrics suited for establishing stressor - response relationships, identification of wetland classes for which these relationships are applicable, and quantitative responses across anthropogenic impact gradients across the Great Lakes basin. We sampled 58 wetlands between 2002 and 2004 using a two-factor experimental design to test biogeography and wetland hydrology and geomorphology as classification factors in stressor-response relationships. We sampled an equal number of "riverine" and "protected" type wetlands, distributed across all 5 lakes and the upper and lower ecoprovince. Within combinations of ecoprovince and wetland type, wetlands were selected to span a gradient in nutrient loading, as inferred from geographic information systems and statistical characterization of watershed landuse and landcover. Our sampling protocol includes characterizing wetland hydrology, water quality, algal composition, fish assemblages, and aquatic habitat. Our results suggest a strong relationship between land use practices and nutrient status in coastal wetlands, and metrics derived from land cover data have promise as nutrient-specific stressor indicators. Geomorphology/hydrology and biogeography were found to be significant in explaining the variance between nutrient indicators and algal responses. These factors also explained patterns in wetland fish assemblages. Nutrient loading is an important stressor for wetlands, directly impacting water clarity and quality, which in turn affect food-web structure and aquatic habitat (e.g., plant composition and cover), and ultimately impact wetland fish assemblages.