Avaliação ecotoxicológica do médio rio uruguai usando o Caenorhabditis elegans para biomonitoramento

Abstract

Uruguay River is part of a relevant Brazilian hydrographic basin that extends from Rio Grande do Sul and Santa Catarina to countries such as Uruguay and Argentina, demarcating borders. Most of the regions bathed by the river are characterized by intense agro-industrial activity. The intense use of pesticides related to the large soy and rice plantations in the south of the country, associated with other factors such as the lack of adequate environmental protection, exposes the Uruguay River to great chances of pollution, compromising the entire ecosystem, putting in potential risk not only the habitat, but the entire population of the region. This study aimed to analyze and correlate the changes in the waters of the Uruguay River in the municipality of Uruguaiana - Rio Grande do Sul, a city known for high rice production, initially with analysis of samples before and after the application of pesticides in crops, extending our study to monthly samples over a period of 12 months. The physicochemical parameters, pH, dissolved oxygen, conductivity, salinity and temperature of the water were initially evaluated for both studies. For the biomonitoring study, we used the free-living nematode Caenorhabditis elegans as a bioindicator model, exposing them to samples collected from the river. The worms were exposed for 24 hours to samples collected under constant agitation and then transferred to solid medium on NGM plates for survival, longevity, reproduction and body length tests. To complement our studies, metals and pesticides were quantified in the samples and in the second project we also used the CF1553 strain, in addition to the wild type N2, in order to observe a possible expression of Sod-3. Some samples from both studies showed the residual presence of pesticides (Tebuconazole, Imazetapir, Clomazone, sulfentrazone and 2,4-D) and metals (As, Hg, Fe and Mn) and was possible to correlate with physiological effects in C. elegans. Several samples, in different periods and locations of the body of the Uruguay River caused a reduction in reproduction, length, survival and lifespan of exposed worms. This research aimed to reinforce the importance of frequent studies in the area of ecotoxicology, due to the constant pollution and impacts on living organisms.