Habitats and littoral zone fish community structure of two natural lakes in southeast Brazil

The fish community and habitat structure in the littoral zone of lakes Pedra and Hortencia, middle Rio Doce Valley, Brazil, were investigated in three sampling periods from August 1992 to May 1993. A total of 9106 fishes were collected, including 11 species in Lake Hortencia and 12 species in Lake Pedra. Diversity was higher in Lake Hortencia, although total fish abundance was the same for both lakes, with no significant temporal differences. The length distribution of the majority of fish species was similar between lakes. Geophagus brasiliensis was the dominant species (number/biomass) in all habitats of the two lakes in all three sampling periods. A striking difference in total fish abundance in relation to habitat types, which we attribute to physical variables, especially the abundance of macrophytes was observed. Negative impacts attributable to the local Eucalyptus sp. plantations were not detected in the fish community structure of Lake Hortencia, which is probably due to the maintenance of the riparian vegetation contributing to similar physical environmental conditions in the littoral zone and high similarity in fish community structure between the two lakes. However, further studies on fish community structure and potential Eucalyptus impacts are suggested as necessary to improve conservation measures of the lakes and their fish faunas.