Underwater observation and habitat utilization of three rare darters (Etheostoma cinereum, Percina burtoni, and Percina williamsi) in the Little River, Blount County, Tennessee

The Little River in Blount County is home to one of the richest darter faunas in East Tennessee. Increases in agriculture and development on several tributaries and the main stem of the Little River are suspected as causes for reduced abundance in fish populations. Earlier research on the Little River identified three species, Etheostoma cinereum (ashy darter), Percina burtoni (blotchside logperch), and P. williamsi (sickle darter), as having low densities. From May – October 2009, snorkel observations were made at 16 predetermined sites along the mainstem of the river to determine abundance and habitat association of these target species, as well as abundance of P. aurantiaca (tangerine darter) for comparison with historic surveys. All fish observed while snorkeling were identified and microhabitat measurements were taken at the location of all target species. Observations included 39 fish species, including 273 P. aurantiaca, 58 P. burtoni, and 7 P. williamsi. Etheostoma cinereum were not encountered during this study. Our observations documented that darter populations during 2009 were significantly different than historic populations, indicating that local populations of the target species have been negatively impacted since the historic survey.

E. cinereum has been consistently difficult to collect on the Little River, and previous sampling efforts have observed this species with less frequency in the last 30 years. The absence of this species in this study may be an artifact of habitat degradation due to development and agriculture, two consecutive years of drought in 2007-2008, or potential sampling bias due to high flows in 2009. Habitat measurements documented that P. burtoni were frequently associated with gravel and cobble substrates. This habitat association is indicative of the feeding habits of P. burtoni who use their padded snout to flip small stones and feed on the aquatic insects found underneath. Turbidity was closely associated with river mile, with a consistent increase in turbidity at downstream sites in the watershed.