Partilha de recursos e variação sazonal na dieta de peixes piscívoros em um reservatório neotropical

Abstract

The fauna of tropical fish is the most abundant and diverse on the planet, with about 4,475 valid species and estimated that the toll could exceed 6,000, with a large number found in Brazil. Since the destruction of habitats is considered a major cause of species extinction, the dams are one of the greatest forms of human intervention in rivers and may lead to the disappearance of species. In spite of major environmental changes imposed by successive dams in major river basins, the understanding of trophic relationships, particularly in top predators, provide consistent information for the implementation of management practices and conservation. The São Francisco River basin is the third largest river basin in Brazil and the first fully inserted within the national territory, representing 7.4% of it. This study was conducted in Sobradinho Reservoir, located in the sub-Middle River and San Francisco was aimed at assessing the diets of five species potentially piscivores, Plagioscion squamosissimus Hoplias malabaricis, Serrasalmus brandtii, and Pygocentrus Piraya Salminus franciscanus, leading into account trophic interrelationships and seasonal changes in water level in the reservoir. Bimonthly collections were made between November 2006 and December 2009 in different parts of the reservoir. Our results show that the five species are potentially piscivores, but showed low levels of dietary overlap and similarity, and were not observed significant seasonal changes in diet of the species.