Longitudinal Patterns of Community Structure for Stream Fishes in a Virginia Tailwater
I examined the abundance, composition, and distribution of 34 fishes within the first 24 km below Philpott Dam on the Smith River, a hydropeaking system in Virginia. Fish were sampled at 12 sites over 8 time periods ranging from 2000 to 2002 across April, June, and October. I evaluated spatial and temporal change in fish community characteristics. Species demonstrated persistent trends in abundance, diversity, and composition throughout the duration of the study. Fish abundance and diversity generally increased with increasing distance from the dam. Fish composition changed minimally across seasons and years, indicating consistent fish assemblages. Distributional patterns suggested a strong response to thermal gradients and presence of tributaries. I concluded that temperature and tributary location directly influence fish community patterns in the Smith River and that the patterns are persistent over space and time.
I characterized spawning microhabitat use and availability, and tested transferability of spawning microhabitat criteria for Etheostoma flabellare and Nocomis leptocephalus, two of the most common species in the Smith River. E. flabellare preferentially selected small and large cobble size rocks for their spawning rock. N. leptocephalus selected areas with slower demersal and mean water column velocities in which to build their mounds. Transferability tests were conducted using spawning microhabitat criteria from the unregulated Roanoke River (Smith 1999). The logistic regression model developed for E. flabellare by Smith (1999), using information on the diameter of the spawning rock, silt, and embeddedness, transferred with most success with over half of the spawning sites and available sites correctly classified in the Smith River.