Alterações histopatológicas, genotóxicas e estresse oxidativo em peixes submetidos a águas superficiais antropizadas

Abstract

Domestic, industrial and agricultural effluents that are directly or indirectly discharged into water bodies carry toxic, genotoxic and mutagenic substances that can trigger harmful processes to ecosystems, especially to the exposed individuals. There are several researches in biomonitoring with bioindicator organisms, thus cytogenetic, histological and oxidative stress tests have been applied in order to detect water bodies contaminated by xenobiotic substances. The aim of this dissertation aimed was to investigate genotoxic and clastogenic cellular alterations, as well as the oxidative damaged presented by fish of the genus Astyanax spp. (lambaris) and Danio rerio (zebrafish), exposed to water of the Ijuí River, through the exposure of two fish species, in three sampling efforts, to the conditions of four points of the Ijuí River, located in the northwest region of Rio Grande do Sul – Brazil, being a major tributary of Uruguay River. Micronucleus and nuclear abnormalities tests were carried out on erythrocytes from individuals of the genus Astyanax spp. (lambaris) exposed in loco for 96 hours to the water of the four points. The results demonstrate significance for the nuclear abnormalities, however, for the micronucleus test, they were not significant. The histological results of the gills show severe and moderate damage for all sampling points compared to the control group. The oxidative stress tests, performed with liver tissue, did not present significant differences for most points. The micronucleus and abnormalities tests carried out with Danio rerio (zebrafish) exposed to waters of the river in aquariums, for 96 hours, presented significance in the nuclear abnormalities analysis for all the monitored sampling points, having alarming values in the second point, which has the characteristic of being the most impacted by agricultural residues, on the other hand, these points did not present significance for micronucleus tests, in the same way as the tests with lambaris. We consider that the results indicate risks of contamination of this water body, that has a socio-economic importance in the consumption of water resources to supply cities and agricultural use.