Spatial variation in reservoir fish assemblages along semi-arid intermittentriver, Curimataú River, northeastern Brazil

With the increased recognition of the importance of the aquatic biodiversity and inherent ecological processes, rigorous examination of the effects of impoundment on smaller rivers and streams is needed. This study compares the diversity and composition of fish on reservoirs along an intermittent river in the Brazilian Northeast. Variation in fish assemblage composition was investigated using multivariate analysis (ordination). A total of 1744 individuals of 22 species was captured and the overall diversity of fish species was consistent with other studies. Ordination was unable to clearly distinguish the fish assemblages according to a-priori criteria (river reach, habitat type and season). The overall hydrological stability, characteristic of reservoirs, and the overall similarity in habitat conditions across reservoirs, coupled with the high dominance of a few species are the most likely factors explaining the high variability within a-priori groups and low similarities between fish assemblages across the reservoirs in the Curimataú River.