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Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Disturbance Ecology IV
LOCAL SCALE HABITAT VARIABILITY AS IMPORTANT SECONDARY PREDICTOR OF MACROINVERTEBRATE ASSEMBLAGES IN URBANIZING CATCHMENTS.
A.H. Roy1, A.D. Rosemond1, and M.J. Paul2. 1Institute of Ecology, University of Georgia, Athens, GA 30602, 2Tetra Tech, Inc., 10045 Red Run Blvd., Owings Mills, MD 21117
Relationships between chemical and physical parameters and macroinvertebrate assemblages indicate that reach scale variables (e.g. particle size variability, specific conductance, and depth) are good predictors of biotic communities across streams. We hypothesized that within-reach habitat variability would also be related to macroinvertebrate assemblages and increase model predictive ability. Macroinvertebrates and physical habitat characteristics were sampled in 5 riffle and 5 bank locations within 10 streams in the Etowah River basin, Georgia, USA. Riffle density was related to velocity, patch length, and moss/macrophyte score, while riffle richness and EPT richness in riffles were predicted by site, velocity, distance to nearest riffle, and patch area. Bank density and richness were also related to local bank habitat variables (bank slope, % rootmat, % bare) and site. When incorporating average catchment, reach, and local scale variables into a multiple regression model, specific conductance was repeatedly the best variable predicting macroinvertebrate integrity. Additional variation in total macroinvertebrate richness across sites could be explained by average bank overhang distance, and % bare bank. Thus, both reach scale chemical and physical parameters (which are correlated with catchment land use) and local scale habitat variability are important in predicting macroinvertebrate assemblages.
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