Effects of Changing Land Use on Macroinvertebrate Integrity: Identifying Indicators of Water Quality Impairment

Abstract

We sampled macroinvertebrates in 30 streams (11-126 krn2 watersheds) within the Piedmont of the Etowah River basin in northern Georgia to examine the relationships between urban land use, physical and chemical characteristics of streams, and biotic assemblages. Percent urban land cover in 1973, 1987, and 1997 was negatively correlated with macroinvertebrate integrity, with the recent land cover exhibiting the highest correlations. The Environmental Protection Agency's visual-based habitat assessment was the single, best overall variable correlated with macroinvertebrate integrity. Specific conductance, average riffle particle size, and standard deviation of stream bed particle size were also highly correlated with indices of macroinvertebrate integrity. Out of the macroinvertebrate indices we calculated, total richness, the Invertebrate Community Index (ICI), and riffle insect richness formed the strongest predictive models with environmental variables, suggesting their importance as water quality indicators in this system. These results demonstrate that macroinvertebrate integrity can be used to assess stream water quality impacts that occur due to changing land use and suggest that stream protection relies on minimizing the percent urban land cover in the catchment.