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Targeting Urban Watershed Stressor Gradients: Stream Survey Design, Ecological Responses, and Implications of Land Cover Resolution
Kuhn, A., N. Smucker, M. Charpentier, C. Cruz-Quinones, C. Elonen, B. Hill, Jim Lake, J. Serbst, S. Whorley, AND J. Wehr. Targeting Urban Watershed Stressor Gradients: Stream Survey Design, Ecological Responses, and Implications of Land Cover Resolution. Presented at Joint Aquatic Sciences Meeting, Portland, OR, May 18 - 23, 2014.
Watershed development is a leading cause of stream impairment. This research examines how watershed development affects periphyton and macroinvertebrates by altering the sources and concentrations of nutrients, carbon, and stressors. Results can be used to develop indicators and inform monitoring and management decisions.
We conducted a stream survey in the Narragansett Bay Watershed designed to target a gradient of development intensity, and to examine how associated changes in nutrients, carbon, and stressors affect periphyton and macroinvertebrates. Concentrations of nutrients, cations, and anions were positively correlated with increasing watershed impervious cover. The 2006 National Land Cover Data (NLCD; 30 m2) underestimated and overestimated impervious cover at low and high intensities, respectively, when compared to higher resolution state land cover data (<5 m2). These differences could affect where ecological responses are predicted to occur along development gradients, and subsequently affect management targets and strategies. Land cover regression models predicted lower background concentrations of nutrients when using NLCD 2006 versus finer resolution state GIS data. As TP increased, microbial phosphatase activity decreased, indicating a shift away from phosphorus limitation. Microbial respiration increased as the ratio of glycosidases to oxidases increased, potentially indicating increased quality of DOC. We are also examining the responses of δ15N and δ13C in periphyton and macroinvertebrates to further examine how watershed development affects sources and availability of nutrients and carbon.