Macroinvertebrates, Watershed Imperviousness, and a Water Quality Index: A Confluence of Georgia Adopt-A-Stream’s Volunteer Data
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Authors
Christopher H. Kodani
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Journal Article, Academic Journal
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Abstract
The relationship between a stream’s macroinvertebrate community as quantified by Georgia Adopt-A-Stream’s Water Quality Index and the impervious surface of an adopted stream’s watershed was weak. Although the average WQI decreased with increasing watershed imperviousness, the R<sup>2</sup> was only 8.3%--an admittedly poor fit. To further investigate, a more comprehensive analysis was performed using forward stepwise regression. This model, which included both imperviousness and the abundance of just 15 out of the 20 kinds of macroinvertebrates, achieved an R<sup>2</sup> of 59.4%. Imperviousness alone may not be a good predictor of WQI, but a combination of selected macroinvertebrate data and imperviousness can yield a better fitting model. Furthermore, mayflies, aquatic sowbugs, clams/mussels, midges, and lunged snails, all of which were excluded from the model because they did not have a significant predictive value for WQI, generally seem to have specific habitat requirements which are dictated by stream-reach, rather than whole watershed characteristics.