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Use of stable isotope analysis in determining aquatic food webs
Citation:
Collins, S. E., J. E. FLOTEMERSCH, M. D. Delong, AND J. H. Thorpe. Use of stable isotope analysis in determining aquatic food webs. Presented at Association of Mid-Atlantic Aquatic Biologists, Berkeley Springs, WV, March 29 - 30, 2012.
Impact/Purpose:
The goal of this research is to develop methods and indicators that are useful for evaluating the condition of aquatic communities, for assessing the restoration of aquatic communities in response to mitigation and best management practices, and for determining the exposure of aquatic communities to different classes of stressors (i.e., pesticides, sedimentation, habitat alteration).
Description:
Stable isotope analysis is a useful tool for describing resource-consumer dynamics in ecosystems. In general, organisms of a given trophic level or functional feeding group will have a stable isotope ratio identifiable different than their prey because of preferential use of one isotope, or fractionation, in metabolic processes. For example, smallmouth bass (a piscivore) would have a higher heavy nitrogen:light nitrogen ratio than a spotfin shiner (an insectivore). Food resource can also be identified in similar m anner using carbon (C) r atios. Food webs and nutrient sources within can thus be established using multiple stable isotopes from individuals at different trophic levels. We hypothesized that food web dynamics would be similar at stream sites with similar hydrogeomorphic properties. Stream order and functional process zone (FPZ) were two methods used to classify 25 sites in the Kanawha River basin (WV and VA). We collected fish from multiple trophic levels (omnivore, herbivore, insectivore, piscivore, etc.) at each site in summer 2010. Fish were identified to species and dissected to remove dorsal muscle tissue. Tissue was then dried at 60C, homogenized, and analyzed for stable isotope ratios. Preliminary results are presented.