Composição de comunidades de peixes bentônicos ao longo do trecho do rio Amazonas, entre os municípios de Manaus-AM e Santarém-PA

Abstract

The communities of benthic fish of the Amazon River were studied after the dry season of 2005, between the cities of Manaus - AM and Santarém - PA, in the period of November-December. The benthic fish had been sampled by Otter trawl and the composition, richness and distribution of spatial variation of the abundance of the benthic fish had been analyzed. A total of 51 samples were taken, being 36 in six points of collection in the Amazon river and 15 samples in three tributaries, Negro, Madeira and Tapajós rivers. We caught 8802 individuals, weighing 50,2 kg had been distributed in 8 orders, 21 families and 146 species or morfhotypes. The orders Siluriformes and Gymnotiformes represented 86.7% of the absolute number of individuals and 87.5% of the weight. The most abundant were Apteronotidae, Doradidae and Pimelodidae. The most diversity and abundant sample was collected in the estuary of the Negro River, with 73 species and 2586 individuals. The Madeira river was the smallest number of individuals, with 94 fish. The Tapajós river total presented a different community of other places. We highlight the areas of the low Solimões river and the main channel of the Amazon river, after confluences of the Negro and Madeira rivers, it`s had presented greater richness and abundant of benthic fish, where we had been captured, respectively, 56 and 48 species. The high diversity found may have been the result of drought occurred in this period.