Food resource partitioning in a fish community of the central Amazon floodplain

Abstract

Diets of most of fish species inhabiting a floodplain lake in central Amazonia were studied over a two years and half period. Based on the percentage of relative occurrence of 11 major food categories a classification of species in 11 feeding guilds is proposed. Many species were found to be specialized feeders. Fish, detritus and insects were the most important food resources supporting the fish community in both seasons, but the proportions of fruits, invertebrates and fish were reduced during the low water season. At the community level mean diet overlap between species was low, suggesting efficient resource partitioning within the community. However mean overlap between unspecialized feeders was high. Based on the 23 most abundant species belonging to the different feeding guilds, there was no difference in mean overlap between seasons. Whereas individual species exhibited diet changes between high water and low water seasons, there was no general pattern of seasonal change within feeding guilds.Os regimes alimentares da maioria das espécies de peixes de um lago de várzea da Amazônia central foram estudados durante dois anos e meio. Baseada nas percentagens de ocorrência relativa de 11 maiores categorias alimentares, uma classificação das espécies em 11 guildas alimentares é proposta. Muitas espécies foram consideradas especializadas em relação aos seus comportamentos alimentares. Peixes, detritos e insetos foram os recursos alimentares mais importantes ao longo do ano, mas as proporções relativas de frutos, invertebrados e peixes foram reduzidas durante a época de águas baixas. A nível de comunidade a sobreposição média entre espécies foi baixa, sugerindo uma partição eficiente dos recursos alimentares. Entretanto, para espécies não especializadas, os valores de sobreposição foram elevados. Baseado em 23 espécies abundantes, pertencentes a diferentes guildas alimentares, não foi observada diferença na sobreposição média entre as estações do ano. Enquanto que certas espécies individuais mostraram mudanças de regime entre épocas de águas altas e baixas, não foi observado nenhuma tendência geral nas modificações sazonais dentro das guildas alimentares.

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