Efeitos do ecossistema no hábito alimentar de peixes: uma comparação entre lagoas e corpo do reservatório

Abstract

The aim of this study was to characterize the diet of the most abundant fish species found in floodplain lagoons of the Mortes River, MG, and in its discharge mouth, in the Funil reservoir, and evaluate the effects of season, type of habitat, size and shape of the lagoon on the diet composition and weight ingested by the species. Samples were collected in August and October 2013, for the dry period, while February and April 2014 represented the rainy season. Fish were captured with gill nets of 2.4, 3, 4, 5, 6, 7, and 8cm mesh sizes in three floodplain lagoons, eight lagoons created by the filling of the reservoir and four sites at the body of the reservoir. The collected samples were fixed in a 10% formalin solution and then conserved in 70% ethanol. The eight most abundant fish species were selected for a diet study trough analysis of stomach contents. The species were feda total of 37 items, allocthonous and autochtonous, of animal and vegetable origin. Neither of the species diet composition was influenced by season; however, Astyanax fasciatus, Geophagus brasiliensis and Hopliasmalabaricus showed significant differences iningestedweight, being fedlarger quantities during the dry season. The type of sampled habitat produced differences in the diet composition of the two species of characin, A.altiparanae and A. fasciatus, in a way that the diet of the individuals captured on the floodplain lagoons was more herbivorous. The weight of the food ingested by the species A. fasciatus and S. nasutus was influenced by the habitat they were in, withboth fed smaller quantities in the reservoir main body. The weight of the food ingested by H. malabaricus decreased with the increase inlago on perimeter. The season was not found to be the main factor to influence the species diets, as much as the type of habitat where they were captured.