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RESPONSE OF COASTAL RIVERINE AND MICROBIAL AND VEGETATION COMMUNITIES TO NUTRIENT LOADING GRADIENTS: MINING SURVEY DATA FOR CRITERIA DEVELOPMENT
Citation:
Detenbeck, N E., T. M. Jicha, C M. Elonen, L E. Anderson, AND D L. Taylor. RESPONSE OF COASTAL RIVERINE AND MICROBIAL AND VEGETATION COMMUNITIES TO NUTRIENT LOADING GRADIENTS: MINING SURVEY DATA FOR CRITERIA DEVELOPMENT. Presented at American Society for Limnology and Oceanography (ASLO), Savannah, GA, June 13-18, 2004.
Description:
A probabilistic survey of Lake Michigan coastal riverine wetlands demonstrated microbial, algal, and vegetation responses to gradients in nutrient loading and N:P ratios. Sediment porewater, exchangeable, and total nutrients were strongly correlated with historic loading rates, after correction for dilution by sediment supply. Potentially mineralizable nitrogen, microbial biomass, and bacterial numbers in the submerged aquatic zone were significantly correlated with historic TN or TP loadings Evaluated sediment phosphatase activity occurred at sediment N:P ratios of 13 or 31 in different vegetation zones. However, high phosphatase in sediments corresponded to low vegetation N:P ratios, suggesting an increased P supply for vegetation. Increases in phytoplankton biomass and thresholds for increased percent blue-greens in periphyton communities along TP gradients differed among systems with stable versus flashy hydrologic regimes. With the exception of five sites with abnormally high water TP and low N:P ratios indicative of point source pollution, tissue N:P ratios suggest P-limitation for wetland vegetation across the range of watershed development. Wetland vegetation P retention proficiency and use efficiency changed sharply at tissue N:P ratios indicative of shifting nutrient limitation.