Distribution of the assembly of fishes in the influence area of an aluminum industry in São Luis Island, Maranhão State

Abstract

Aspects of the structure, composition and diversity of the ictiofauna of the estuaries under the influence of an aluminum industry, were studied and the results are shown in this paper. The bimonthly sampling was carried out at four sites in the estuary, in the period between May, 2002 and March, 2003. Diversity was analyzed by using the Shannon-Wiener index and similarity among the capture sites was analyzed by Jaccard and Morisita coefficient and Cluster Analysis, based on presence-absence matrixes of the species. A total of 2,838 individuals were captured, belonging to 44 species, 12 orders and 25 families. Of this total, seven species were represented with less than 1% of the total number of sampled individuals and 11 species accounted of less than 1% of total sample weight Regarding the species number the dominancy were the Sciaenidae (11) and Ariidae (6). The community structure revealed higher participation of Anableps anableps, Colemesus psittacus, Genyatremus luteus and Sciades herzhergii, as the species with the highest percentage, namely 51.5% of specimens captured. The values of diversity indices were low and they showed little variability among the sites sampled. Conversely, major species richness was observed in Boa Razão creek. The similarity analysis formed three different groups, which were not distinguishable across of the seasonality.