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Developing Ecological Indicators for Nutrients and Urban Impacts to Streams in Coastal Watersheds
Citation:
Smucker, N., A. Kuhn, Mike Charpentier, C. Cruz, C. Elonen, B. Hill, Jim Lake, AND J. Serbst. Developing Ecological Indicators for Nutrients and Urban Impacts to Streams in Coastal Watersheds. Society for Freshwater Science Annual Meeting, Milwaukee, WI, May 17 - 22, 2015.
Impact/Purpose:
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.
Description:
Increased nutrient loads associated with human activities are among leading causes of impairment to streams and receiving waterbodies. For streams draining to the environmentally and economically important Narragansett Bay estuary, we developed indicators based on (1) nitrogen and carbon stable isotope ratios of periphyton and macroinvertebrates and (2) microbial enzyme activities. Streams tended to be P limited, as indicated by nutrient concentrations and high microbial phosphatase activity that decreased as TP concentrations increased. Nitrate concentrations significantly increased with human sources associated with urban land cover. Increased nitrate concentrations were significantly correlated with greater 15N in periphyton and macroinvertebrate scrapers, detritivores, and predators, making these potentially useful indicators that also provide insight into changes in food webs. Microbial respiration decreased as the ratio of glycosidases to oxidases decreased, potentially indicating lower quality of DOC in urban streams. Stable isotopes and macroinvertebrate communities indicated that vegetated riparian buffers likely had benefits for ecological communities, even in moderately urban streams. Lastly, landscape indicators are being developed using GIS to characterize how spatial patterns of land cover are linked to stream conditions.