Micronucleus test in fish and physicochemical parameters in water at Cocais dam, Minas Gerais

Abstract

The organisms known as bioindicators are used to assess changes in the aquatic environment. Incorporated chemical substances in natural environment interfere in the development of these organisms. The research had as objective to avaluate the water quality of the Cocais dam, in Patrocínio, Minas Gerais, using physical-chemical parameters of water and micronucleus test in fish. In this study were used fish of the species Oreochromis niloticus L. (Tilápia-do-nilo) introduced in the dam after its construction. Genetic material from twenty-eight individuals was collected at two points, P1 at the dam and P2 at the source. The cytological analysis was performed using an optical microscope and 4000 erythrocytes were examined per fish. For the physico-chemical characterization of the water samples were performed two collections during the rainy and dry periods, both in the dam and in the source. The parameters analyzed (turbidity, pH, Dissolved oxygen - OD, total dissolved solids – SDT), nitrate ammoniacal Nitrogen values were lower than those established in the legislation. The conductivity was higher than value indicated by CETESB, characterizing an indirect measure of the concentration of pollutants. Whit the results obtained in the micronucleus test a higher frequency of micronucleus can be observed in the cells of the fish captured in the dam, suggesting that the water is contaminated by genotoxics, that altered the genetic material of these bioindicators.