Associations Between Fish and Benthic Macroinvertebrate Biotic Integrity and Non-Point Source Pollution Estimates in the Nolichucky River Watershed
Alford, J. B., and H. S. Gotwald.  2018.  Journal of the Tennessee Academy of Science.

We used the Soil and Water Assessment Tool (SWAT), a GIS-based method that estimates sediment, phosphorus and nitrogen yields using remotely-sensed land cover, hydrologic, and geomorphic characteristics of watersheds, to determine if metrics of biotic integrity are associated with non-point source runoff. During 2014, SWAT model estimates were made for 19 sites in the Nolichucky River watershed that were subsequently sampled during 2014-2016 for fish and benthic macroinvertebrates using standard procedures developed by the Tennessee Valley Authority (TVA) and the Tennessee Department of Environment and Conservation (TDEC), respectively. Partial canonical correspondence analysis, after accounting for spatial proximity of sites, showed a significant association between benthic macroinvertebrate IBI metrics and SWAT model estimates, whereas partial correspondence analysis suggested a strong relationship between some fish metrics and non-point source pollution. For benthic macroinvertebrates, organic nitrogen and phosphorus yield were positively associated with % nutrient-tolerant taxa, but negatively associated with % clingers. Sediment yield was negatively associated with % clingers, taxa richness, and Ephemeroptera-Plecoptera-Trichoptera (EPT) richness. For fishes, sediment and nutrients were positively associated with % hybrids and catch per unit effort, but negatively associated with native species richness. The SWAT model is a publically-available GIS tool that managers and researchers can utilize to assess non-point source pollution impacts on freshwater ecosystems. Our findings are limited to the Nolichucky River watershed, but other researchers should use SWAT models and indices of biotic integrity to examine the link between sediment and nutrient loads and aquatic ecosystem health in other regions with different fauna.