Biomarcadores de contaminação aquática em baiacus (Sphoeroides Testudineus) coletados no estuário do Rio Pacoti - CE

Abstract

For many years chemical data have served as the exclusive and more traditional indicators of contamination. However, in the last decades ecotoxicological studies have contributed in understanding environmental degradation and in the establishment of new environmental quality parameters. In such context, biomarkers analyses focus on the evaluation of environmental quality and responses to pollutants based on health parameter measurements of local organisms. The fish Sphoeroides testudineus (Linnaeus, 1758) belongs to the family Tetraodontidae and was chosen as biological model for this study. In chapter I, the answer of S. testudineus submitted to the feminine hormone estradiol (E2) under laboratorial conditions is evaluated, aiming at the validation of this species for studies with endocrine disruption and monitoring of tropical estuary contamination. The biometry was not a good indicator of the effects of endocrine disruption, as no alterations were observed. There were no alterations of GSI and HIS in E2-treated groups as well. Histopathological analysis of gonadal tissues showed no alteration, while in the hepatic tissue, there were evidences of tissue damage, including vacuolization, picnosis and necrotic areas. Vitellogenin (VTG) detection in plasma of S. testudineus using western blot demonstrated that a positive band was observed in the females, but also in most males and juveniles including those from the control group. These data strongly suggested the presence of endocrine disruptors in the estuary of Pacoti river and prompted us to chapter II of this working, that aimed to the evaluation of the environmental quality of Pacoti river quality using S. testudineus as the indicator and different biochemical biomarkers and histopathology as endpoints. There was an accentuated difference in the number of male and female fishes (1 male to 4.6 females). The body weight showed a great variation (mean ± SD = 45.07 ± 32.48g), while the length was much more homogen (mean ± SD = 11.34 ± 2.57cm). The variation coefficient of GSI and HSI was 82.50% e 54.37%, respectively. All females presented ovary containing previtellogenic oocytes and were mainly in the phase II of gonadal maturation. There were only 2 male identified trough histology and 22 juveniles with undifferentiated gonads. While there were no lesions or alterations in the gonads, the liver tissue presented intense vacuolization, picnosis and some necrotic areas. Vitellogenin was detected on the plasma of females, one male and 14 juveniles, reinforcing the presence of endocrine disruptors in the estuary. The analysis of enzymatic biomarkers showed that the activity of analyzed enzymes, with the exception of GST, were higher in the liver than in the gills. To better understand the real meaning of this enzymatic fluctuation, more studies are necessary with fishes from unpolluted areas. Although the present work is still a preliminary analysis, S. testudineus could be considered a suitable model to evaluate environmental quality. Present data strongly suggest the contamination of Pacoti river estuary, one of the most important water resources from Ceará state, since there evidences of liver damage and also feminization.