PERSISTENCE AND STABILITY OF FISH COMMUNITY STRUCTURE IN A SOUTHWEST NEW-YORK STREAM

We used multivariate and nonparametric statistics to examine persisten ce and stability of fish species in the upper 43 km of French Creek, N ew York. Species occurred in upstream and downstream groups in 1937 th at persisted in 1979. However, the downstream group expanded its range in the drainage from 1937 to 1979 at the expense of the upstream grou p. A dam prevented further upstream expansion of the downstream group. Ranks of species abundances were stable, as tests of group similarity were significant. The abundances and distributions of benthic species were stable across seven sampling dates in 1980 despite several flood s and repeated removals by sampling that could have altered community structure. We conclude that the fish community in French Creek persist ed and was stable over the 42-yr interval, 1937-1979, and that abundan ces of benthic species were stable in summer 1980.