Avaliação da qualidade ambiental em um sistema de lagos manejados na região do baixo Rio Solimões, Amazônia, Brasil

Abstract

The management of lakes has been efficient in the recovery of fish stocks in the Amazon. However, little is known about the effects of the management system on lakes for the quality of these environments. Evaluating the implications of this system for environmental quality can be a difficult process due to the limited tools available for floodplain environments in the Amazon. The Biotic Integrity Index (BII) is a tool that has been shown to be promising, accessible, easy to understand, and inexpensive to monitor biological resources. The aim of this study was to evaluate the impact of the management system on the environmental quality of lakes through the use of the BII in the region of the lower Solimões River, in the Amazon region of Brazil. For the capture of fish, gill nets were arranged in six lakes, which belong to three management categories: preservation, management and commercial use. A total of five samples were sampled in 2017 and early 2018. The number of fish sampled was 4565, distributed six orders, 25 families and 113 species. The final index was composed of seven metrics related to species richness and composition, trophic structure and abundance of fish. By means of BII, we evaluated that the environmental quality in the preservation lakes is good, in the management lakes the quality is regular and in the lakes of commercial use the quality is poor. We confirmed the results of the BII through multivariate statistics that allowed us to reject the hypothesis that the environmental quality in lakes is not influenced by the management system in lakes, in such a way that we verify that preservation lakes have better quality than management lakes and commercial use. The classification determined by the IIB shows that the management system is a satisfactory model to assure the environmental quality in the lakes, indicating through the response of the ichthyofauna, that this system present in the island of Paciência - implemented through the fishing agreement - fulfills its role of preserving the fishing stock and alternatively contributes to the quality of the environment as a whole.