Dieta, hábitos alimentares e morfologia trófica de peixes de pequeno porte, em lagoas da planície de inundação do alto rio Paraná, Brasil.

Abstract

Cap.1: In this study we analyzed the diet and trophic morphology of seven Tetragonopterinae species in nine isolated lagoons of the Paraná river floodplain, Brazil, during 2001. Diet showed trophic segregation among species in all studied environments. Astyanax altiparanae, Astyanax fasciatus, Hemigrammus marginatus and Moenkhausia intermedia consumed aquatic and terrestrial insects; to Bryconomericus stramineus and Moenkhausia sanctaefilomenae there was co-dominance of insects and microcrustaceans in the diet, whereas to Hyphessobrycon eques microcrustaceans were the most important food resource. Diet of this latter species was very different when compared it with the others. Feeding overlap coefficients were low (inferior than 0,4) for all the combination pairs. Trophic morphology, including mouth, tooth, gill rakers and stomach showed apparently the same pattern to the seven species. However, there was significant interation between standard length (F7,333 = 84,89; p < 0,0001) and the species (F6,333 = 13,87; p < 0,0001). Higher mean to intestine length were verified to A. altiparanae e A. fasciatus and the smaller mean to H. eques. Comparing all these results is possible concluded that the dimension of trophic niche segregated these species. Thus, the co-existence and higher abundance of this smaller fish in shoreline of the lagoons is explained by hight feeding flexibility of these species, by few specificity of the feeding tract and by wide food supply given by aquatic macrophytes.