Variáveis hematológicas, imunológicas e regulação iônica em Tilápia-do-Nilo, Oreochromis niloticus coletadas em lagoas da Grande Vitória -Espírito Santo- em áreas de influência de atividades metalúrgicas

Abstract

Aquatic ecosystems, especially those located close to urban centers and metallurgical activities, are receptors of wastewater and deposition of particulate matter from surrounding activities. Brazil is one of the largest producers and exporters of iron ore, with emphasis on the state of Espírito Santo, where two of the largest metallurgical complexes in the country are located, the Tubarão and Ubu Complex. In this scenario, this study aimed to evaluate the blood, gills and kidneys of Nile tilapia, Oreochromis niloticus collected in coastal lagoons influenced by metallurgical activities (Maemba and Carapebus) and in an aquaculture facility (Alegre) located in Alegre, 140 km from metallurgical industries. Water and sediment, and blood, gills and kidneys of O. niloticus collected in these lagoons and in Alegre were analyzed for the presence and concentration of metals. In fish, the relative condition factor (Kn) and multibiomarkers (hematological, immunological, physiological, genotoxicity and mutagenicity) were analyzed in the blood (plasma and erythrocytes) to evaluate animal health, and multibiomarkers (biochemical, morphological and physiological) were analyzed in the gills and kidneys to verify the mechanisms of osmotic and ionic regulation. The physical and chemical parameters of the water influence the ecosystem of these lagoons, the bioavailability of metals and the osmoregulation. The analysis of the main components separated Alegre from the other lagoons that are influenced by waste from metallurgical industries. Although some metals in the water and sediment of Alegre were higher than in the lagoons, the concentrations of metals in the blood of fish from Alegre were lower compared to that of fish collected in Maemba and Carapebus, while in the gills and kidneys, some metals were higher. higher than in the lagoons. Fish from the Maemba M1 lagoon showed anemia and lower osmolality. Fish from the Carapebus lagoon had higher percentage of micronuclei suggesting the presence of genotoxic agents in the water or sediment, and had the highest Cl- concentration, which may be related to an adjustment to the brackish water in which they live. The activity of Na+/K+-ATPase, H+-ATPase and carbonic anhydrase enzymes, ionocyte fractional area in the gill surface and in renal tubular area varied in the fish of lagoons due to physicochemical characteristics and metal concentration of the lagoons. In conclusion, fish from Alegre have the best health conditions when compared to fish located in lagoons close to metallurgical activities confirming the hypothesis that fish collected in lagoons close to mining and steel activities have a more compromised health due to the human influences around them compared to fish from a region without these industries (Alegre).