Habitat Partitioning and Associated Morphological Differences Among Three Species of Catostomidae (Teleostei: Actinopterygii) in the South Fork Roanoke River, Virginia

Abstract

The upper Roanoke River has 11 species of Catostomidae including Moxostoma ariommum, Bigeye Jumprock; Moxostoma cervinum, Blacktip Jumprock; and Thoburnia rhothoeca, Torrent Sucker . Resource partitioning appears to be a key component of maintaining diverse fish assemblages with habitat and food partitioning cited as especially important in communities containing members of the same family. The diets of these species have been documented in previous work revealing only modest differences among them. Snorkeling observations and subsequent quantification of microhabitat were conducted to illuminate habitat partitioning among these morphologically and ecologically similar species. Thoburnia rhothoeca inhabited the shallowest, fastest water, over the smallest substrate, and Moxostoma ariommum inhabited the deepest, slowest water, over the largest substrate, with M. cervinum intermediate for all habitat variables. In an effort to correlate morphological adaptations to these different microhabitats, 22 body measurements were included in a Principal Component Analysis revealing a bigger eye for M. ariommum and more fusiform bodies for T. rhothoeca and M. cervinum consistent with findings in other species inhabiting faster waters. Other correlations among morphology and microhabitat were less clear.