Habitat Selection and Partitioning Among Darters in Two Tributaries of the Clinch River, and Stream Restoration Effects on Substrate Profile

The group of fish referred to as darters is extremely biodiverse. Often, several closely related species will inhabit the same areas of streams, and prior research has investigated how these species may be partitioning the resources in low-order streams in which they are sympatric. The habitat partitioning of darters in two streams in the Clinch River system, Coal and Cove Creeks, was investigated. The study sites were picked due to their involvement in both physical and biological stream restoration efforts within the last several years, including the collection, translocation, and reintroduction of rainbow darters (Etheostoma caeruleum) from reference sites in Cove Creek to the impacted and restored sites in Coal Creek. Snorkel surveys were used to identify adult darters and mark their locations, and the substrate in the darters’ immediate surroundings was quantified. These measurements were compared to transect survey data to assess whether darters were selecting for habitat, and then compared among the subpopulations of darters encountered. The numbers of adult redline (Nothonotus ruffilineatum), snubnose (E. simoterum), and rainbow darters encountered were great enough to proceed with analyses of habitat usage. It was determined that darters were selecting for habitat nonrandomly, and that all three of the species most encountered associated with coarse rocky substrate. Differences in habitat associations among species appeared to be driven by the environmental factors each species encountered at the site scale. In a secondary study, effects of stream restoration were assessed by comparing substrate profiles of the sites where darter surveys were conducted. Each site was classified as either natural, impacted, or restored. Then, the collected substrate data from transect surveys at each site were compared. The substrate profile of the most upstream site in Coal Creek, a site that has undergone stream restoration efforts, most closely resembled those of the ‘natural’ reference sites in Cove Creek. Substrate profiles of the more downstream sites of Coal Creek did not resemble those of the reference sites as closely, regardless of stream restoration effort.