Tabela V. Relações estatísticas entre a abundância (CPUE) de diversos grupos de espécies transpostas e as vazões e precipitação no rio Mucuri. Variáveis transformadas para a escala logarítima; modelos significativos encontram-se em negrito. EspéciesVazão

DIET OF FOUR SPECIES OF LEPORINUS (CHARACIFORMES, ANOSTOMIDAE) DURING FORMATION OF A RESERVOIR IN SOUTHEAST BRAZIL.The study reports the changes ocurred in feeding ecology of fish species during a tropical river reservoir formation. It was analysed the stomachal contents of 399 individuals belonging to four species of genus Leporinus (L. elongatus Valenciennes, 1849, n=157; L. friderici (Bloch, 1794), n=87; L. octofasciatus Steindachner, 1917, n=107; L. amblyrhynchus Garavello & Britski, 1987, n=48) during formation of Nova Ponte reservoir, State of Minas Gerais, Brazil, in 1993 and 1994. Specimens were separated by sampling period, according with the rate of filling of the reservoir, and standard lenght classes. The species had included in diet vegetal and animal items of autochtone and alochtone origin in several proportions. L. amblyrhynchus fed on basically dipterans in all the sampling periods and length classes. L. elongatus had presented a diverse diet, with predominance of dipterans and vegetal items, and changed the consumed items proportions along the sampling periods and between lenght classes. L. friderici diet was composed mainly by terrestrial insects during the rapid filling period, that were later substituted by fishes and vegetal items. Ontogenetic trophic changes were observed in this species. L. octofasciatus presented a well characterized herbivorous diet, without trophic ontogeny, but with a opportunistic character. Just three pair-species, L. amblyrhynchus-L. elongatus, L. friderici-L. octofasciatus and L. elongatus-L. octofasciatus, have presented some high value of trophic overlap in at least one sampling period. In spite of the fishes of the genus Leporinus being classified like omnivorous in a general way, the differences found between diets of these four species suggest that there is structuration of trophic niches in the reservoir.

ABSTRACT. Diet ofpirambeba Serrasalmus brandtii Rcinhardt (Teleostei, Characidae) in four floodplain lakes in São Francisco river, Brazil. The diet of pirambeba Serrasalmus brandlii Reinhardt 1874 was studied in four floodplain lakes in São Francisco river. The main food items consumed were chunks offish flesh, small tishes, scales, fins and aquatic insects. Trophic ontogeny was observed in ali lakes. The amowlt of fishes in the diet of S. brandIU increased with the length of the individuais, while the amount of aquatics insects, fins and scales decreased. Aquatic insects were consumed in greater proportion during the wet season. Fish ingestion, inc\uding scales and fins, was correlated with the abundance of fishes. KEY WORDS. Serrasalmus brandlii, diet, floodplain lakes, São Francisco River A subfamília Serrasalminae inclui piranhas e pirambebas e constitui um grupo de peixes com dieta, tática de caça e comportamento social bastante diversificados (GOULDING 1980;BRAGA 1981;NICO & TAPHORN 1988;SAZIMA & MACHADO 1990 (GOULDING 1980; GOULDlNG el a!. 1988; LEÃO el aI. 1991) e nordeste do Brasil (BRAGA 1981).Na bacia do rio São Francisco ocorrem duas espécies de Serrasalminae: a piranha vermelha Pygocenlrus piraya (Cuvier, 1820) e a pirambeba Serrasalmus brandlii Reinhardt, 1874. Embora a pirambeba represente geralmente uma grande oercentagem da biomassa de peixes em suas lagoas marginais (BRAGA 1964), não !xistem estudos sobre a alimentação desta espécie nestes ambientes.Este trabalho teve como objetivo determinar a dieta da pirambeba (Serrasalmus brandlii) em quatro lagoas marginais do rio São Francisco, relacionando sua dieta à disponibilidade de alimento. MATERIAL E MÉTODOS Área de estudoA bacia do rio São Francisco, com área de 631.133 km 2 , corresponde a 7,4% do território brasileiro. Situa-se entre os paralelos 21 o e 7 0 S, o que lhe confere características climáticas bastante variadas. As precipitações variam entre 350 mm

This book is dedicated to the memory of our friend Volney Vono. We miss him, his funny stories, and his ecological knowledges.

ABSTRACT. Dict changes of the trahira Hoplias malabariCIIs (Bloch) (Erythrinidac, Characiformes) due to piscivorous introductions in Rio Doce valley lakes.