Effects of Watershed and Stream Habitat Conditions on Fish Communities in the Upper Roanoke River Watershed, Virginia

Vann F. Stancil and Donald J. Orth
Dept of Fisheries and Wildlife Sciences, Virginia Tech Cheatham Hall, Blacksburg, VA 24061-0321 540-231-5320 vstancil@vt.edu

Fish communities are impacted as urbanization continues to alter landscapes. Our study compared fish communities in watersheds of varying degrees of urbanization to determine ways to mitigate impacts and direct future development scenarios. We sampled 43 sites in the upper Roanoke River watershed, Virginia during late Spring and Summer of 1998 and 1999. Using one pass backpack electrofishing, we sampled 22 small, 13 medium, and 8 large stream sites with average stream widths from 2.8 to 11.0 m. Stream habitat variables included depth, substrate size, habitat type, and canopy closure while watershed land use conditions were categorized as forest, agriculture, and low or high intensity development. We compared fish community attributes using metrics for Index of Biotic Integrity (IBI) applications to stream habitat and watershed land use variables at three spatial scales. We collected 49 species from 9 families totaling 54,809 individuals. Results indicate that fish community attributes depend on several factors; some, such as stream width and elevation, reflect natural differences in streams while others, such as watershed land use and sedimentation, are due to anthropogenic effects. Our results identify factors influencing fish community attributes, suggest land development scenarios that may lessen stream impacts, and identify useful metrics for IBI applications.