Study of fish diet at Grande river downstream from Itutinga hydroelectric power plant, Minas Gerais, Brazil

The aquatic biota of the Parana river basin has been impacted by several dams. This study aimed characterize and compare seasonally the fish feeding of Grande river fish fauna, downstream from Itutinga Power Plant. In this river stretch it is expected the reduction of seasonal effects due to flow regulation. Data collection was conducted in January and July 2010 with gill nets and trawls. The fishes were fixed in formalin and preserved in alcohol for stomach contents analysis. The diet was characterized by Feeding Index (IA) and the guilds each species belongs was determined by the chi super(2) test. The feeding of each species and the occurrence of food items were compared in periods of drought and rain using nMDS and SIMPER analysis. We analyzed 809 stomachs from 32 fish species categorized in piscivorous, herbivorous, ilyophagous/detritivorous, ilyophagous, algivorous, frugivorous, invertivorous and generalists guilds; the generalists had the highest species richness. The nMDS indicated lower diet diversification in July, when it was observed an increase of plant, invertebrate and sediment occurrences. However, differences in diet were lower than expected. This study expanded knowledge about fish feeding habits and local dam effects on species diet as a result of flow regulation.Original Abstract: A biota aquatica da bacia do rio Parana tem sido impactada por varias barragens. Este estudo teve como objetivo caracterizar e comparar sazonalmente a alimentacao dos peixes do rio Grande, a jusante da usina de Itutinga. Neste trecho de rio e esperada a reducao do efeito sazonal devido a regulacao do fluxo. A coleta foi realizada em Janeiro e julho de 2010, com redes de emalhar e de arrasto. Os peixes foram fixados em formol e conservados em alcool para a analise dos conteudos estomacais. A dicta foi caracterizada pelo indice alimentar (IA) e a guilda a que cada especie pertence foi determinado pelo teste de chi super(2). A alimentacao de cada especie e a ocorrencia dos itens alimentares foram comparadas nos periodos de seca e chuva utilizando-se as analises de nMDS e SIMPER. Foram analisados 809 estomagos de 32 especies de peixes categorizadas nas guildas piscivora, herbivora, iliofaga/detritivora, algivora, frugivora, invertivora e generalista, sendo esta a guilda de maior riqueza de especies. O nMDS indicou menor diversificacao na dieta em julho, quando foi observado um aumento na ocorrencia de vegetal, invertebrados e sedimento. Este estudo ampliou o conhe