Dieta de peixes nativos e não nativos na região litorânea de duas lagoas do médio Rio Doce MG

Abstract

In this study we evaluated the diet of native and non-natives fish of the Carioca and Gambazinho lakes (Parque Estadual do Rio Doce, MG). Samples were made bimonthly from October / 2011 to August / 2012. A total of 791 individuals was collected, both juveniles and adults, belonging to seven native species in lake Gambazinho and 355 individuals, belonging to five native and 3 non-native species in lake Carioca. A total of 604 and 160 stomachs were analyzed, for lake Gambazinho and Carioca respectively. With the analysis of stomach contents, it was possible to infer the feeding habit of the species. It was found that youths and adults of the same species showed a similar diet, however, trophic ontogeny in Oligosarcus solitarius in Gambazinho lake occurred. The variation in feeding habits of Hoplias gr. malabaricus present in both lakes is indicative of the change in Carioca lake, because of the presence of non-native species such as the fish-eating Cichla kelberi. In Carioca lake, individuals of Hoplias gr. malabaricus were found to be insectivorous, whereas in Gambazinho lake this same species was considered piscivorous. The minnows, Astyanax intermedius of Gambazinho lake and Astyanax aff bimaculatus in Carioca lake showed insectivorous feeding habit. The zooplanktivorous species Hasemania sp., in Carioca lake, showed the highest consumption of copepods among the juveniles and the highest consumption of cladocerans among the adults. Of the eight species collected in Carioca Lake, the larvae of the Diptera Chaoborus sp., which is abundant in this lake, were considered an important item for three species: H. gr. malabaricus, C. kelberi and Hoplosternum littorale. In Gambazinho lake, the cichlids showed benthivorous-omnivorous feeding habit and Oligosarcus solitarius, although juveniles and adults consumed shrimp, the former also ingested terrestrial insects and the latter also ingested fish. The Piankas index showed that, in both studied lakes there was no food overlap or it was low for most species (<0.25). According to Levins Index (B) all species were are considered experts (B <2), and only the non-native Pygocentrus nattereri was considered generalist (B = 5.0).