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Wednesday, June 6, 2007 - 11:15 AM
208
Evidence of stream food web alterations due to the anthropogenic watershed land-use change across Metro Louisville, Kentucky (USA)
Wesley M. Daniel, BS, Biology, University of Louisville, 2315 Glenmary Ave., Apt F4, Louisville, KY 40204, Jeff Jack, Department of Biology, University of Louisville, 139 Life Sciences Building, Louisville, KY 40292, and Philip Lienesch, Ph.D., Biology, Western Kentucky University, 1 Big Red Way, Bowling Green, KY 42101.
Human alteration of watershed land-use due to urbanization brings prominent changes in the structure and function of urban stream ecosystems. We analyzed the stable isotope signatures of current and historical samples across an urban to rural gradient in Metro Louisville, Kentucky. The stream food webs where reconstructed using fishes, macroinvertebrates, periphyton algae and detrital leaf material from twenty-one sites. We found urban stream food webs had a total nitrogen (δ15N) enrichment of 4-5 ‰ over corresponding rural sites. Carbon (δ13C) signatures from streams with > 17% watershed impervious surfaces showed an increase of 3-4 ‰ over back ground levels. Both of these heavy isotope enrichments can be traced in the museum specimens to show historical land-use change within the watershed. The stable isotope data was analyzed against structural components of streams (hydrology, riparian width, water chemistry, and community structure) to show how stream food webs have changed during watershed development. This will determine what restoration strategies might be successful and appropriate in these systems.