Aspectos ecológicos e sociais da invasão de peixes em lagos naturais do médio Rio Doce, MG, Brasil

Abstract

The Rio Doce Lake System has been the local of non-native fish introductions since the 1970s. As a result, were observed reductions in native fish species and impacts on zooplankton community. This study aimed to identify which stages of the invasion process that non-native species are found; the impact of these species in the invaded communities structure, and the perception of local fishermen about the invasion process. The stages were identified by: (i) population and reproductive analysis of non-native fish species collected with multi-mesh gillnets, seine net and sieve in two lakes: lake Carioca (2009-2010), located inside de Rio Doce State Park (PERD), and lake Jacaré (2010-2011), located outside the park, and (ii) prediction models of non-native species occurrence in 19 lakes of the system. The impacts in native community of lakes Carioca and Jacaré were verified using richness, diversity and equitability indices, constancy of occurrence analyses and abundance estimation with whittaker-plots. the perception of the local fishermen about invasion process were analyzed by semi-structured interview conducted on lakes with recreational fishing club (lakes Jacaré and Aguapé), located in the surrounding areas of the PERD, and lake Dom Helvécio located in PERD, where fishing for non-native species is allowed for visitors. The reproductive and population analyzes indicated that non-native species are adapted to the environment, with reproductive success and self-sustaining populations. Impacts were identified in the community invaded, with dominance by non-native species and low abundance of native species. The prediction models of non-native species indicate that propagule pressure is the main factor responsible for the presence of these species in lakes, even inside the PERD. These results indicate that the species are in the later stages of the invasion process, and it is necessary their population control. Local fisherman perceives the impact of some of these species in the environment and is willing to participate in management actions. Therefore, we recommend the planning of participative management, integrating PERD and surroundings in order to control population of non-native fish in the system and prevent the introduction of new species.