O uso de espécies de peixes nativas para avaliação de ecotoxicidade dos rios da Bacia do Rio Paranaíba e Grande

Abstract

The deterioration of aquatic environments has been characterized as one of the biggest public health problems in the world, with the release of pesticides, domestic and industrial effluents the main responsible for the contamination of water resources. Considering that sanitation conditions are precarious and that a large part of the population does not have access to drinking water, monitoring the quality of water sources that serve human consumption is essential. However, the evaluation of water quality, according to conventional parameters, based on physical-chemical indicators, fails to translate, by itself, the impacts of contamination on living organisms exposed to the impacted environment. Thus, ecotoxicological studies in situ are used to increase the sensitivity of studies about environmental quality, complementing the results of characterization of the environment from tests with living organisms. This work employed native species (with the approval of the Ethics Committee on the Use of Animals - CEUA / UFU - Analysis 085/16, Protocol 040/16) in the evaluation of the water quality of the rivers of the Paranaíba and Grande River basin, directing the use of these species Astyanax altiparanae and Cichlassoma paranaense as candidates for sentinel organisms in environmental biomonitoring programs. For this, in addition to evaluations of physical-chemical parameters, the biological effects of fish exposure to water samples collected in these tributaries were investigated, with an emphasis on assessing the damage caused to the genetic material of the exposed organisms. The results confirmed the presence of contaminants in the water (Aluminum, Iron, Manganese, Zinc and Copper) and sediment (Chrome, Cadmium and Nickel), being found levels above that recommended by the Brazilian environmental legislation. In addition, our research revealed that exposure to contaminated water was positively correlated with genotoxicity in erythrocytes from fish of the species A. altiparanae and C. paranaense, popularly known as Lambaris and Acarás, respectively. The results reinforce the importance of carrying out biological tests for the early detection of effects resulting from exposure to contamination by industrial and domestic effluents, which must be adopted as a complementary parameter to the conventional physical-chemical methods of assessing water quality. This doctoral thesis was prepared in accordance with the rules established by the Graduate Program in Genetics and Biochemistry at the Federal University of Uberlândia, and divided into three chapters: CHAPTER I - Applications of the micronucleus assay for in situ assessment of freshwater genotoxicity using neotropical freshwater fishes. It is a review article, which presents research and ecotoxicological concepts for the development of environmental assessment experiments in situ, using native fish as sentinel organisms (bioindicators). In this study, biological models were evidenced for the evaluation of the ecotoxicity of natural and anthropogenic pollutants, through the use of genotoxicity biomarkers. CHAPTER II - Eco-genotoxic responses of the native fish species following exposure to Copper-contaminated freshwater samples It consists of an in situ experiment, using a freshwater Neotropical cichlid (Cichlasoma paranaense) as a biological model to assess the ecogenotoxicity of water samples collected in different locations. The results indicated that the species tested was sensitive to samples contaminated by effluents containing copper, from the disposal of agrochemicals in the region, showing high levels of genotoxic alterations. CHAPTER III - Genotoxicity assessment of polluted urban streams using a native fish Astyanax altiparanae The research evaluated the genotoxicity of samples collected in streams of the Jordão River, a tributary of the Paranaíba River, Brazil, using Astyanax altiparanae, which was shown to be significantly sensitive to the different levels of contamination tested.