Composição e estrutura da comunidade de peixes em um trecho do rio Cachoeira Grande, na reserva ecológica da Michelin, Igrapiuna, Bahia, Brasil

Abstract

Considering the diverse ichthyofauna of the world, Brazil inland waters from stand out, for which the knowledge about fish species composition is very scarce and many times absent, as it happens at the Atlantic Rain Forest fragments in Bahia. Studies about the fish fauna from these regions contribute to the knowledge about the species, where many can be endangered of extinction or not have been scientifically described, and consequently for the preservation of the same. The objective of the present study was to characterize the composition and structure of the fish community from Cachoeira Grande River, at the Reserva Ecológica da Michelin (REM), Igrapiúna, Bahia. Bimestrial and standardized samples were made during the period between June 2007 and June 2009, at three fixed areas at the Cachoeira Grande River (P1, P2 e P3), two upstream and one downstream the Pancada Grande Waterfall. A total of 1.829 specimens were captured, corresponding to a total weight of approximately 86.763 kg and 28 species, distributed in 14 families and 22 genera. The collector curve does not indicate signs of stabilization, showing the necessity of more samples at the area. The families Characidae, Cichlidae and Anostomidae were the most representatives in numbers of the individuals for all the areas, but the importance of the two last was due to the species Geophagus brasilienses e Leporinus bahiensis, respectively. There is no significant difference between the abundance and biomass of the species and the areas sampled, period of the year and environmental parameters. The richness stands out at P3 in relation to the other areas. The dominance was diferente between P1 P3. P3 stood out for its greatest diversity. Sycidium sp. (Gobiidae) represents a first register of this genus for Brazilian continental waters. The testimony material was deposited at the Fish Division of the Museu de Zoologia da Universidade Estadual de Feira de Santana. At a general view, the Cachoeira Grande River at the Reserva Ecológica Michelin is well preserved, with few impacts on its marginal vegetation and with the major differences in the species composition being determined by the Pancada Grande Waterfall, which functions as a natural barrier for the fish community and prevents the occurrence of mmarine species due to the absence of estuarine influence at the areas upstream of the Waterfall.