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STRESSOR-RESPONSE RELATIONSHIPS AT NATIONAL AND REGIONAL SCALES FOR FISH AND BENTHOS ASSEMBLAGES
Citation:
HERLIHY, A. T. AND J. VAN SICKLE. STRESSOR-RESPONSE RELATIONSHIPS AT NATIONAL AND REGIONAL SCALES FOR FISH AND BENTHOS ASSEMBLAGES. Presented at American Fisheries Society annual meeting, San Francisco, CA, September 02 - 06, 2007.
Description:
Between 2000 and 2004, the U.S. Environmental Protection Agency conducted a nationwide probability survey of over 1,600 wadeable streams to assess ecological condition in terms of water chemistry, physical habitat and macroinvertebrate assemblages. The survey also measured stream fish and periphyton assemblages in 12 western states (750 streams). Nationally, macroinvertebrate Index of Biotic Integrity (IBI) scores were most correlated (Spearman rank) with rapid bioassessment habitat score (r=0.46), percent fine substrate (r=-0.46), and nutrients/turbidity (r=0.39). The strength of IBI-stressor correlations varied widely among ecoregions. For example, the correlation of IBI with percent watershed in agriculture varied from -0.55 in the Upper Midwest to 0.02 in the Northern Plains. Correlations between stressors and predictive model O/E scores were lower than those observed with IBI scores. Nationally, the highest correlations with O/E scores were with rapid habitat score (r=0.31), turbidity (r=-0.21), and percent fine substrate (r=-0.21). In the West, where multiple assemblages were sampled, the fish and macroinvertebrate IBIs both responded to similar stressors with about the same strength of correlation. Strongest correlations were observed for nutrients, chloride, sulfate, percent fine substrate and percent watershed in agriculture (r>0.55).