This QR project resulted in a report and a publication.
The Kentucky arrow darter (Etheostoma spilotum, KAD) is a species of conservation concern due to its fragmented distribution and threats from anthropogenic stressors. In this report, I evaluate the relationship between KAD abundance and stream conductivity in the upper Kentucky River basin. Stream conductivity represents an indicator of exposure to headwater mining operations and/or shale gas development and may have direct or indirect effects on stream fish distributions. I used nonlinear regression techniques to evaluate change points and associated confidence intervals for KAD abundance related to conductivity levels. I also evaluated blackside dace (Chrosomus cumberlandensis, BSD) occurrence in this regard as a contrast to KAD. For instance, BSD may support relatively high local abundances within streams whereas KAD are typically much more rare, often supporting only 1 or 2 individuals observed within sampling reaches. I used KAD and BSD data supplied by the US Fish and Wildlife Service (Tennessee and Kentucky Field Offices), Kentucky Department of Fish and Wildlife Resources, Kentucky Division of Water, and Kentucky State Nature Preserves Commission. Nonlinear regressions indicated a threshold decline in KAD abundance at 258 microS/cm (95% confidence intervals 155-590 microS/cm), above which abundances were negligible. BSD abundances exhibited a similar pattern. Nonlinear threshold declines for BSD were observed at 343 microS/cm and 95% confidence intervals bounded this relationship between 123-632 microS/cm. I supplemented KAD and BSD analyses with boosted regression models to evaluate the relative importance of conductivity versus other measures of environmental condition (i.e., land use, watershed size, gradient, flow). Boosted regression results indicated that stream conductivity was the strongest predictor in separate analyses of KAD and BSD abundance. The similar responses of ecologically distinct taxa to conductivity gradients suggest the general importance of this water quality attribute for stream fish ecology in central Appalachia. This research was supported by the USGS-USFWS Quick Response Program in FY2013. Elements of this research were provided in a letter to USFWS Tennessee Field Office dated 7 June 2013 and in a presentation at the 143rd Annual Meeting of the American Fisheries Society in Little Rock, Arkansas (September 8-12, 2013).
