Studies of stream fish ecology emphasize the long-standing view that local factors determine local diversity. However, a growing body of evidence form studies of other groups of organisms suggests that local diversity is strongly influenced by diversity at broader spatial and temporal scales. The local determinism hypothesis predicts that local communities are in equilibrium with the local environment, and thus, are only as complex as local habitat. The regional enrichment hypothesis predicts increases in local diversity with increases in regional diversity, regardless of habitat complexity, and local adjustments in niche breath and niche overlap to accommodate the added diversity. A three-year study of local and regional influences on stream fish diversity in the southeastern U.S. is proposed to test predictions of the above hypotheses. Fishes will by sampled, and data on habitat variability gathered, from small, upland streams in five southeastern drainage basins differing in diversity. The effects of differences in basin-scale diversity on local species-abundance relationships and habitat utilization patterns will be analyzed to determine how basin level diversity is accommodated locally. The goal of this research is demonstrate the degree to which diversity in small local areas depends on processes operating outside of the areas. The results should have special relevance for biological conservation efforts.
