Composição e estrutura da ictiofauna do único reservatório da bacia do rio Parnaíba, Brasil.

Abstract

The Parnaiba River has its headwaters located in the Serra da Tabatinga from upwelling of Chapada das Mangabeiras. In this study, aiming to an inventory in the dam and downstream points, it was also conducted an analysis of the structure, conducting bimonthly collections, between September 2013 and October 2014, in which we used standardized gill nets (from 3 to 10 cm between opposing). The traps installation points were randomly chosen in order to cover the greatest number of aquatic microhabitats found in the lake of "Boa Esperança", and downstream in order to capture the greatest possible diversity of fish. The Shannon index and Pielou's on fish fauna diversity research and richness estimators Jackknife 1 and 2, Chao 1 and 2 and Cochran were used to measure sample adequacy and the similarity between the downstream sections was analyzed by the Jaccard coefficient and Sørensen coefficient. As a result, in the catches were found a total of 823 specimens belonging in six orders and 20 families, for a total of 38 species. The most abundant species to upstream corresponded to the Pellona flavipinnis, while the downstream stretch was the Myleus asterias, in terms of the total catch in both systems, with 14 endemic species. The richness estimators indicated a low diversity; the individuals are not distributes itself equitably. The sample sufficiency reached the asymptote from the 10th collection. The dam of Boa Esperança presented a Ichthyofauna a low similarity between upstream and downstream a fish fauna with a majority of species concentrated in two orders, Characiformes and Siluriformes and a predominance of migratory in the downstream segment. The results obtained through the dispersion of Morisita index indicated random dispersion of the Assembly. The data obtained is still scarce on the regional biodiversity, provide subsidies to the decision makers on the main measures to be effective in the conservation and use of biological resource often threatened by the construction of new hydropower projects.