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DEVELOPING INDICATORS OF NITROGEN SOURCE IN COASTAL ECOSYSTEMS
Citation:
McKinney, R A., W Nelson, AND M Charpentier. DEVELOPING INDICATORS OF NITROGEN SOURCE IN COASTAL ECOSYSTEMS. Presented at N2001 International Nitrogen Conference, Potomac, MD, October 14-18, 2001.
Description:
Several studies have linked stable isotope ratios of biota to nitrogen source. In particular, ribbed mussels show promise as sensitive indicators of the origins of nitrogen inputs to coastal ecosystems. Here we expand on previous work which demonstrated that mussel isotope ratios correlated with watershed land use characteristics in a New England estuary. Mussels were collected from coastal salt marshes which correspond to 15 watersheds included in a recent SCOPE Nitrogen Balance Study of large river systems in the mid-Atlantic and northeast, USA. Mussel isotope ratios ranged from 5.9? in Casco Bay, Maine to a high of 13.9? in upper Chesapeake Bay. Applying a model which relates watershed land use to mussel isotopic signature, we saw differences across the region between measured and predicted values that may result from inconsistencies in the scale and categorization of regional land-use data or differences in estuarine geomorphology and hydrology. Measured isotope signatures may also reveal localized inputs of nitrogen not accounted for in large scale land use data that would need to be considered by managers and regulators when developing monitoring and assessment strategies for coastal eutrophication.