Composição taxonômica e ecologia trófica da ictiofauna em reservatórios do semiárido brasileiro

Abstract

The studies of diversity survey and dynamics of fish communities of reservoirs from semiarid are important as a basis for ecological studies and conservation of species. Extreme environmental events in ecosystems such as reservoirs and changes in fishes' morphology can cause the change of eating habits. The first manuscript of this study aimed to make the taxonomic survey of the ichthyofauna from two reservoirs of the basin of the River Paraíba do norte and and their respective downstream (Epitácio Pessoa and Argemiro Figueiredo). The second manuscript aimed to analyze the trophic structure of the reservoir Argemiro de Figueiredo and possible seasonal variations and ontogenetic in feeding on an extended drought event, for this manuscript the following hypotheses were tested, (I) the trophic guilds show changes depending on the hydrological regime of the reservoirs of semi-arid which, affects the abundance of prey items reducing the preferences of the species in the lowest water volume period, (ii) reducing the water volume of the reservoir causes changes in food availability and in the trophic strategies of individuals, Leading the species to override their trophic niches in the lowest period of water volume, which may result in interspecific and intraspecific competitions. To achieve the goal of the first manuscript, Monthly collections were made with various fishing tackle, in the period from October 2014 to September 2015 in the reservoirs of Epitácio Pessoa (Boqueirão) and Argemiro de Figueiredo (Acauã), belonging to the basin of the River Paraíba do norte, in the semiarid of Northeast. Within the reservoirs 2057 specimens were collected distributed in 17 species, 10 families and three fishes orders. In the downstream areas of the reservoirs were collected 271 individuals belonging to 24 species, 11 families and five orders. To achieve the objectives of the second manuscript, were selected for the analysis of the diet, the most abundant species in the reservoir Argemiro de Figueiredo, and for the ontogenetic analysis these species were divided into youth and adults. Seasonal variation in the study was negligible for the variation of the diet of most species, While ontogenetically the species range the dietary preferences, reflecting in the formation of different trophic guilds for each species, and even with relatively high values of niche overlap, species coexist, because they adopt different strategies for a trophic partition in the reservoir.