| Resumo: |
For a dietary study, specimens of Astyanax bimaculatus, Astyanax schubarti, and Moenkhausia intermedia were caught monthly with seines-nets in six lakes (Pau Veio, Porto Rico, Três Amigos, Mutum, Pontal, and Canal do Meio), on the floodplain of the Upper Paraná River, from March 1992 through February 1993. We analyzed stomach contents of 599 A. bimaculatus, 293 A. schubarti, and 394 M. intermedia, by the Occurrence and Points methods, combined in the Alimentary Index (AI). This analysis revealed that these species have broad dietary spectra. A. bimaculatus was an omnivore, with a tendency toward herbivory-insectivory. In most of the lakes it consumed terrestrial insects, followed by higher plants and microcrustaceans. A. schubarti was an omnivore, consuming the same type of items in the different lakes, in different proportions depending on the locality. M. intermedia was a planktophage, feeding mainly on cladocerans (more than 50%) in all the lakes except for Pontal, where higher plants were predominant (45.1%). Although A. bimaculatus and A. schubarti consumed similar items in the different localities, detrended correspondence analysis (DCA) showed distinct segregation among the three species in all lakes studied.
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