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LOCAL RIPARIAN VERSUS WATERSHED INFLUENCE ON CHEMICAL AND MACROINVERTEBRATE INDICATORS OF STREAM WATER QUALITY IN TWO REGIONAL SURVEYS
Citation:
Herlihy, A. T. AND P R. Kaufmann. LOCAL RIPARIAN VERSUS WATERSHED INFLUENCE ON CHEMICAL AND MACROINVERTEBRATE INDICATORS OF STREAM WATER QUALITY IN TWO REGIONAL SURVEYS. Presented at American Geophysical Union Fall Meeting, San Francisco, CA, December 15-19, 2000.
Description:
We compiled data from regional stream surveys in two areas of the U.S. to examine whether indicators of human disturbance at the local riparian scale (e.g., site canopy density, riparian human disturbance) or the watershed scale (e.g., percent basin in agriculture, basin road density) were most strongly associated with macroinvertebrate and water chemistry indicators of stream ecological condition. Data from the mid-Atlantic region were taken from a randomized, probability sample of wadeable streams conducted by the EPA's Environmental Monitoring and Assessment Program (EMAP) in spring 1993 and 1994. Data from Oregon were taken from wadeable streams in the Willamette River basin compiled from four different projects conducted between 1994-1997 and represent a mixture of sites selected at random and those hand-picked to represent gradients in condition. All sites were sampled in the field using the same EMAP wadeable stream protocol. Sample size was about 100 sites in each area. Watershed condition indicators were strongly related to water chemistry indicators (total N, P, and chloride) in the mid-Atlantic and Oregon. A multiple regression model with an rsquare around 0.5 can be constructed with just watershed variables. Riparian condition indicators were only weakly related to stream chemistry in Oregon and unrelated in the mid-Atlantic. Riparian condition indicators were not related to macroinvertebrate metrics in the mid-Atlantic but were in Oregon. Watershed variables were related to macroinvertebrates in both study regions.