Seasonal and long-term changes in the fish assemblage of a small stream isolated by a reservoir

Because reservoirs are known to affect upstream fish communities, we assess ed change in fish assemblages of a reservoir tributary from surveys conduct ed 10 and 50 years post-impoundment. We collected fishes front five section s of Buncombe Creek (a tributary to Lake Texoma, Oklahoma-Texas) in each se ason of 1995, and compared assemblages in each section among seasons. We al so compared assemblages in each section pooled over all seasons to the asse mblage present in 1954-1955. We used measures of persistence (species compo sition, Jaccard's Index), stability (relative abundance, Percent Similarity Index), and Detrended Correspondence Analysis to compare assemblages withi n 1995 and between the two surveys. There was little change in assemblages throughout 1995, with high stability in the most upstream section. The most change occurred between spring and summer. We collected 31 of the 47 speci es caught in 1954-1955, plus five additional species. The assemblage in the most upstream section of the creek showed the least persistence and the le ast stability between the two surveys. Longitudinal differences in fish ass emblages of the creek were more pronounced in 1954-1955 than 1995. We discu ss the possible role of isolation of Buncombe Creek from the free-flowing p ortion of the Red River in the extirpation of Notropis buchanani, Labidesth es sicculus, and Fundulus zebrinus.