Ecotoxicology assay for the evaluation of environmental water quality in a tropical urban estuary

Abstract Most studies evaluating the impacts of river pollution in the semi-arid region of Brazil have been geared towards physiochemical analyses, and investigations of the adverse effects of water pollution on associated organisms are scarce. This study aimed to evaluate the water quality in the Poxim river estuary in Aracaju, Sergipe throughout the dry and rainy season by evaluating the survival of the microcrustacean Mysidopsis juniae and physicochemical analyses. The evaluation of physiochemical parameters revealed a decrease in dissolved oxygen content in the rainy season. However, there was a significant reduction in microcrustacean survival in samples during the dry season, when the river flow is reduced and effluents become concentrated. These results suggest that pollutants received and carried by the waters of the Poxim River contribute to the reduction of environmental quality in the estuary, and this impact may vary according to dry and rainy patterns, that are uncertain considering the impacts of climate change on tropical regions.