An Evaluation of the Effects of Small, Man-made Impoundments on Stream Macroinvertebrate Communities and Water Quality in Eastern Tennessee

Semi-quantitative benthic macroinvertebrate samples were collected from riffles above and below four small impoundments in eastern Tennessee. Watershed and habitat surveys and a variety of field measurements were performed for each sample site and each sampling event when appropriate. Samples were collected quarterly (seasonally) during a one-year period. The goal of the study was twofold: (1) to determine whether or not differences in stream macroinvertebrate communities above and below impoundments existed and if so, (2) to attempt to evaluate the possible effects of the impoundments on the downstream benthic community and water quality.

One-hundred and fifty-four distinct macroinvertebrate taxa in 73 families were represented by all samples collected during the study. Multimetric and multivariate analysis methods were utilized to assess semi-quantitative samples. Total number of taxa (Taxa Richness) and number of less tolerant taxa (especially mayflies, stoneflies, and caddisflies) were generally lower in stations below impoundments than in those stations above the impoundments. A number of other biometrics, indices, and water measurements showed similar trends of impairment in below impoundment stations when compared to above impoundment stations. Analysis of variance tests using a number of biometrics and indices indicate that significant differences exist between the macroinvertebrate communities of streams examined. Effects of the impoundments are implicated. However, factors such as other anthropogenic habitat alterations may also be contributing to some impairment trends.