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Communication at the NABS Annual meeting, Keystone, 2000
(184) EFFECTS OF IMPERVIOUSNESS ON BENTHIC MACROINVERTEBRATE ASSEMBLAGES, WATER QUALITY, AND HABITAT CONDITIONS IN NORTHERN VIRGINIA'S BULL RUN WATERSHED.
J. Arciszewski and R.C. Jones. Department of Biology, George Mason University, Fairfax, VA, USA 22030
Located in Northern Virginia, Bull Run is a fourth order stream with a watershed that is a major source of drinking water, but is subject to rapid suburban development. For two years, we analyzed differences in the biotic, chemical, and habitat characteristics of about 20 sites representing three levels of imperviousness. Impervious surface cover was determined for each site by calculating percentages of land use types within each subwatershed. Six biotic metrics were calculated and composited for a final Index of Biotic Integrity (IBI) score. Imperviousness ranged from 9% to 59%. IBI scores ranged from 3 to 36 out of a possible 36. ANOVA revealed a significant difference between the IBI scores of low versus medium and high imperviousness sites. Linear regression showed a significant relationship between IBI scores and imperviousness. Statistically significant differences were found for all six metrics as a function of imperviousness. Habitat score means were significantly different between the low and high imperviousness sites and regressions of habitat scores versus imperviousness were also significant. Principal component analysis showed a distinct separation of low imperviousness sites from medium and high level sites. Imperviousness was confirmed as a strong predictor of biotic and habitat conditions.
Presented at 9:15 AM on Wednesday, May 31, 2000 in Water Quality and Land Use I
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