River waters near to agricultural sites in the Northeastern Brazil (Maranhão State) cause genetic damage in Nile Tilapia (Oreochromis niloticus)

Munim River is a small basin (15,918.04 km2, 320,000 inhabitants) in northeastern Brazil (Maranhão state), whose water quality has been threatened by pesticides, untreated domestic and industrial wastewater discharges, and solid waste disposal ( Presoti and Cutrim, 2011 ). These pollutants may bring several problems to the aquatic biota, such as mutagenic and carcinogenic effects ( Bolognesi and Hayashi, 2011 ) including risks to human health. Therefore, it is critical to understand the potential impacts of xenobiotics on this river basin, especially their genotoxic and mutagenic effects. We investigated the genotoxic and mutagenic potential of the Munim River waters to assess the impact of the presence of xenobiotics on the aquatic biota.(AU)

Aquatic life protection index of an urban river Bacanga basin in northern Brazil, São Luís - MA

Abstract Bacanga River Basin faces environmental problems related to urbanization and discharge of untreated domestic sewage, which compromise its ecosystem health. Due to the small number of studies that assessed its water quality, the present study aimed to assess the current status of this ecosystem based on the aquatic life protection index. Samples were carried out every two months, in a total of six events, in six sites along the basin, where the water samples were collected to assess physicochemical parameters and calculate the trophic state index and the index of minimum parameters for the protection of aquatic communities. The data were also compared with values determined by the resolution National Environment Council - CONAMA 357/05. Our results reveal significant changes in the water quality of Bacanga River Basin. An increase in nutrients and chlorophyll-a concentration led it to eutrophication. The surfactant values were high and put in danger the aquatic biota. Dissolved oxygen rates were below the values allowed by the resolution in most sites sampled. The current water quality is terrible for the protection of aquatic life in 61.92% of the sites sampled.

Resumo A Bacia Hidrográfica do rio Bacanga (BHRB) apresenta problemas ambientais relacionados a urbanização e lançamentos de esgoto in natura que comprometem a qualidade desse ecossistema. Devido ao reduzido número de estudos associados à avaliação da qualidade da água no local, este estudo teve como objetivo avaliar a situação atual desse ecossistema por meio do Índice de Proteção da Vida Aquática. Seis amostragens bimestrais foram realizadas em seis pontos ao longo da bacia, coletando parâmetros físico-químicos para a aplicação do Índice de Estado Trófico e Índice de Parâmetros Mínimos para a Proteção da Vida Aquática, relacionando-os com a resolução Conselho Nacional do Meio Ambiente - CONAMA/357. Os resultados revelaram alterações significativas na qualidade da água da BHRB, o aumento de nutrientes e das concentrações de clorofila-a conduziram ao um estado geral de eutrofização. Os valores de surfactantes foram altos colocando em risco a biota aquática e as taxas de oxigênio dissolvido estiveram abaixo do permitido pela resolução na maioria dos pontos amostrados. A situação atual da qualidade da água para proteção da vida aquática é péssima em 61,92% dos pontos amostrados.