Dissertation Research: Defining Spatial Scales of Energy Flow through River Food Webs using Stable Carbon and Nitrogen Isotopes

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99-01983Power/FinlayDDIG: Defining spatial scales of energy flow through river food webs using stable carbon and nitrogen isotopesTrophic linkages between terrestrial ecosystems, headwater streams, and downstream rivers are a fundamental feature of lotic ecosystems, but the scale of the processes that mediate food web exchange at a given site remain poorly defined. Two general approaches have characterized efforts to understand river food webs. The first approach analyzed changes in carbon sources and ecosystem function along longitudinal gradients from headwaters to large rivers. A contrasting approach has focused on understanding controls of community structure and function using experimental methods on a much smaller spatial scale. This project will examine stable isotope ratios of biologically active elements such as carbon and nitrogen to link these approaches by providing information about river food web processes at intermediate scales. This research is critical to understanding the spatial scales that are important to mobile top predators in rivers (i.e. fish), and could help guide management of rivers. The research will also help ecologists determine the appropriate scale of investigation in future river food web studies.