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Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Urban Ecology II
CHANGES IN STREAM BIOLOGICAL ASSEMBLAGES IN RESPONSE TO URBANIZATION.
E.M. Giddings1, T.M. Short2, C.M. Albano1, R.L. Baskin1, T.F. Cuffney3, G. McMahon3, J.C. Coles4, and H. Zappia5. 1U.S. Geological Survey, 2329 W. Orton Circle, Salt Lake City, UT 84119, 2U.S. Geological Survey, 345 Middlefield Rd., Menlo Park, CA 94025, 3U.S. Geological Survey, 3916 Sunset Ridge Rd., Raleigh, NC 27607, 4U.S. Geological Survey, 10 Bearfoot Rd., Northborough, MA 01532, 5U.S. Geological Survey, 2350 Fairlane Dr., Suite 120, Montgomery, AL 36116
During the summer of 2000, 31 urban stream sites in 12 drainage basins were sampled near Salt Lake City, Utah, as part of a multi-regional assessment of the effects of urbanization on water quality and biological communities. An index of urban intensity, based on land cover, infrastructure, and socioeconomic factors, was calculated for each site in order to rank the magnitude of urbanization in each drainage basin while minimizing natural landscape variability. Changes in assemblage structure of biological communities in response to urban intensity were examined at each site. Assemblage structure of macroinvertebrate communities appeared to vary spatially along a gradient of urbanization. Invertebrate and EPT taxa richness generally declined in response to increasing urbanization. In contrast, multivariate analysis of fish assemblages indicated that fish communities responded to spatial changes in hydrologic conditions independent of urbanization. Similarly, diatom diversity did not vary among sites concomitant to changes in urbanization, but appeared more responsive to local conditions of near-bed velocities and substrate properties. Initial results suggest that in these urban streams biological metrics based on macroinvertebrate community structure may be the best bioindicator of changes in stream conditions associated with spatial changes in urbanization intensity.
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