Changes in Fish Assemblage Due to Restoration of a Channelized Stream in West Tennessee

In aquatic systems, the loss of habitat heterogeneity due to stream channelization is known to cause altered species compositions and reduced species richness and diversity.  Because of the well-recognized effects of channelization on river systems, stream restoration has become an important tool in the effort to prevent further loss of biodiversity.  In the summer of 2008, the West Tennessee River Basin Authority began a project to restore a 1300-meter section of Crooked Creek (a tributary of the South Fork Obion River) in Carroll County, TN.  This restoration effort included the addition of approximately 2000 meters of stream by constructing a new stream channel that more closely resembles typical stream morphology.  Water was allowed to flow into the constructed channel at the end of August  2010.  The goal of our project was to document the response of the fish assemblage in Crooked Creek to the restoration effort.  We used back-pack electrofishing surveys to compare the fish assemblage in a channelized portion of the stream (prior to connection) to that of the constructed meandering portion.  Throughout the course of this study, we collected 3713 individuals including 48 species and 16 families of fishes.  Upon completion of the restoration efforts, species richness and diversity was found to be substantially lower in the restored reach of the stream than species richness and diversity was prior to the restoration efforts.  The results suggest that stream restoration may cause an initial decrease in species richness and diversity; however, we expect that as the physical factors in the restored reach change over time, more species will be able to successfully colonize this area, thus creating a successful restoration in terms of protecting biodiversity.