SPECIES COMPOSITION AND DIVERSITY OF DECAPOD CRUSTACEANS THROUGHOUT THE LOWER SÃO FRANCISCO RIVER, NORTHEASTERN BRAZIL

Resumo

The aim of this study was to analyse the structure of the decapod crustaceans community (taxonomic composition, abundance, diversity and distribution in the lower São Francisco region, located in the northeast Brazil, which extends from Paulo Afonso, Bahia, to the mouth, between the states of Alagoas and Sergipe, and is an important ecosystem and one of the biggest lentic environments in Brazil and South America. The species were sampled, within a period of three years, in fifteen sites, manually and using drag nets. The organisms were tagged and fixed in 70% alcohol. Posteriorly, the material was sent to the research lab and identified. In order to analyse data, an analysis of variance with a posteriori multiple comparisons was carried out to test the null hypothesis that the diversity throughout the river is homogenous. A total of 3.103 individuals were sampled, comprising 10 families and 30 species. Was verified predominance of the family Palaemonidae in what touches abundance, specially of the genus Macrobrachium. The sites with the greatest taxonomic richness corresponded nearest to the estuary. Our analysis rejected the null hypothesis, allowing us to conclude that the fauna is compartmentalized.