Elasmobranch populations have significantly declined in recent decades due to anthropogenic activities, with chemical contamination comprising one of the main threats to this group. Although some biochemical biomarkers have been utilized to assess elasmobranch health, especially concerning metal and metalloid contamination, associations with genotoxic biomarkers are still scarce and non-existent for Brazilian Amazon coast sharks. Herein, metals, metalloids, reduced glutathione (GSH), glutathione S-transferase (GST), metallothionein (MT), and nuclear anomalies (micronucleus, nuclear buds, and bilobed cells) were determined in gills, liver, and muscle tissues of Nurse sharks (Ginglymostoma cirratum) from the São Marcos Estuarine Complex, Maranhão, Brazil. Females exhibited significantly higher As concentrations in muscle (23.14 ± 13.98 μg g-1) and gills (4.53 ± 2.10 μg g-1) compared to males (3.98 ± 2.61 μg g-1 and 1.51 ± 0.41 μg g-1, respectively) (p < 0.05). Males showed higher Se concentrations in muscle (0.52 ± 0.02 μg g-1) compared to females (0.32 ± 0.09 μg g-1) (p < 0.05), while Rb levels were higher in male liver (0.28 ± 0.05 μg g-1) than in females (0.18 ± 0.04 μg g-1) (p = 0.001). No significant differences were observed for Hg, Ti or rare earth elements (Ce and La) between sexes (p > 0.05). Higher GSH concentrations and GST activities were noted in gills and liver, while MT concentrations were higher in muscle. Low genotoxic damage frequency was observed, likely due to the species' sedentary lifestyle and efficient DNA repair system. Moderate to strong correlations between metals/metalloids and biochemical/genotoxic responses were detected, particularly in females, highlighting the protective role of GST against DNA damage. Protective effects of Se against Hg were observed in the liver. Metal concentrations did not exceed regulatory limits, although bioaccumulation patterns and physiological responses suggest that Nurse sharks are exposed to environmental contamination, with As and Se accumulation.
Keywords: Antioxidant; Biomarkers; Elasmobranchii; Nuclear anomalies.
Copyright © 2025 Elsevier B.V. All rights reserved.