Marcadores de estresse oxidativo em peixes (Astyanax sp. e Danio rerio) expostos a efluentes urbanos e agrícolas no bioma pampa

Abstract

Aquatic ecosystems are under constant risk due to industrial, agricultural and urban activities, compromising water quality and preservation of aquatic biota. The assessment of toxicological impacts caused by pollutants to aquatic environment using biomarker measurements in fish can provide reliable data to estimate sub-lethal effects posed by chemicals in contaminated areas. In this study, fish (Astyanax sp. and Danio rerio Hamilton, 1822) exposed to agricultural and urban effluents at the Vacacaí River, Brazil, were tested for potential signs of aquatic contamination. This river comprehends one of the main watercourses of the Brazilian Pampa, a biome with a large biodiversity that has being neglected in terms of environmental and social-economic development. Sites S1 and S2 were chosen by their proximity to crops and wastewater discharge points, while reference site was located upstream of S1 and S2, in an apparently nondegraded area. Fish muscle and brain tissues were processed for determination of acetylcholinesterase as well as oxidative stress related biomarkers. The results showed signs of environmental contamination, hallmarked by significant changes in cholinesterase activity, expression of metallothionein, antioxidant enzymes, glutathione levels and activation of antioxidant/cell stress response signaling pathways in fish exposed to contaminated sites when compared to reference. Based on these results, it is evidenced that urban and agricultural activities are posing risk to the environmental quality of water resources at the studied area. It is also demonstrated that cell stress biomarkers may serve as important tools for biomonitoring and development of risk assessment protocols in the Pampa biome.