Metal and metalloid contamination, oxidative stress and genotoxicity in Nile Tilapia (Oreochromis niloticus) from an important eutrophicated lagoon in southeastern Brazil.

Coastal lagoons are highly susceptible to chemical contamination, due to their proximity to urban and industrial areas. This seasonal cross-sectional study based on primary data collection investigated the effects of metal and metalloid exposure on Nile tilapia (Oreochromis niloticus) from Jacarepaguá Lagoon (LJPA), a eutrophicated and urbanized coastal ecosystem in southeastern Brazil. Fish (n = 44) were sampled over one year, covering all four seasons at five fixed locations distributed across the lagoon, concurrently with surface water collection. Metal and metalloid concentrations in liver and muscle tissues were quantified by inductively coupled plasma mass spectrometry (ICP-MS). Analyzed biomarkers included MT, SOD, GST, GSH, LPO, and DNA damage (comet assay). Poor physicochemical and microbiological water quality according to Brazilian legislation were observed. Sampling during the spring and summer revealed greater metal diversity in tissues, likely influenced by increased rainfall and runoff. Arsenic, Cd, Hg and Pb were detected in both muscle and liver. Superoxide-dismutase activity decreased by 38-66.5 % in liver and 35-78 % in muscle, while GST activity in muscle decreased by 67.1-73.5 %. Muscle MT levels increased by 39-280 % across seasons, with peak liver MT values observed during spring (C4). Hepatic CARB increased by 119-662 %, especially in summer (C5), and the highest liver LPO levels were recorded in autumn (p < 0.05). Significant correlations between metal concentrations and biomarkers included negative associations between Ti and LPO (ρ = -0.93) and MT (ρ = -0.85), and between Hg and GSH (ρ = -0.90). Muscle LPO was negatively associated with Ni (ρ = -0.72), while GSH showed positive correlations with Cd, Ni, Ti and Fe. DNA damage was significantly higher in individuals collected during the summer (C5), when several metals were detected, suggesting genotoxic effects likely driven by seasonal factors. A Principal Component Analysis revealed distinct seasonal patterns of both metal bioaccumulation and physiological stress, with greater separation among muscle samples and stronger associations with oxidative biomarkers in liver. These findings highlight the need for environmental monitoring and management strategies to mitigate the impacts of metal pollution on aquatic life in urban coastal lagoons.