Metal/metalloid concentrations and multi-biomarkers in blood of Nile tilapia living in coastal lagoons near metallurgical industrial areas: an integrated evaluation

Anthropogenic activity associated with metallurgy affects nearby aquatic ecosystems by contaminating them with metallic effluents (e.g., liquid and aerosols). This study evaluated the metal/metalloid contamination of two coastal lagoons with different physical and chemical water characteristics, Carapebus (brackish water) and Maembá (freshwater), located near metallurgical industries, and an aquaculture facility, Alegre (freshwater), located far away from the industries. The lagoons are in the state of Espirito Santo, the largest steel producer and iron ore exporter in Brazil. Relative condition factor (Kn) and multiple blood biomarkers in Nile tilapia (Oreochromis niloticus), a common species in all sites, were evaluated in these sites. A total of 27 metals/metalloids were analyzed in water, sediment, and fish blood (cells and plasma). The hematological, immunological, physiological, and genetic biomarkers were analyzed in blood. Metal/metalloid concentrations varied in each matrix of each site. Fish from Maembá (site M1) had lower Kn, presented anemia, and had higher leukocytes and plasma lysozyme and glucose levels. Fish from Carapebus had higher micronucleus and cortisol levels. Fish from the lagoons exhibited higher respiratory leukocyte activity. Multivariate analysis separated Alegre from the two lagoons and emphasized the difference between them and fish responses. The correlation of some metals with erythrocyte DNA damage (Zn, Sr, Sn, and Ag), total leukocytes (Zn, Sr, Sn, Ag, V, Cr, and La), lymphocytes (Cu and Ni), and eosinophils and cortisol (Fe, As, and, Pb) in fish from Maembá and Carapebus showed that toxicity depends on the physical and chemical characteristics of water, which affect metal speciation. The interaction of abiotic factors and metals/metalloids in water also implies that fish adjust to maintain homeostasis.