Assessment of effects of water trace element pollution and abiotic factors on muscle and otolith microchemistry and muscle fatty acid profiles, and health risks in populations of Chelon auratus (Risso, 1810) sampled from Mauritanian and Tunisian waters.

内容摘要

This study investigated the influence of trace element pollution and abiotic factors on the muscle and otolith microchemistry, and muscle fatty acid (FA) profiles of Chelon auratus sampled from the Etoile Bay (EB, Mauritania) and Ghar El Melh (GM, Tunisia) stations in April 2024. Environmental analysis revealed significant physicochemical gradients, with EB exhibiting higher temperatures (20.6 ± 0.5°C) and GM showing higher dissolved oxygen (DO) and salinity. Pearson's correlation revealed a strong positive relationship (r = 0.98) between trace element/Ca ratios in water and muscle tissues, identifying temperature as the primary driver of bioaccumulation variance (R2 = 0.672), while DO and salinity showed significant negative correlations. Conversely, pH had no statistically significant impact. Principal Component Analysis (PCA) explained 91.65% of the total variance, clearly separating the two sites. EB variables clustered with higher temperature and trace element/Ca ratios (Zn > Pb > Ni > As > Cr), showing increased polyunsaturated fatty acids (PUFAs), specifically eicosapentaenoic (EPA), docosapentaenoic (DPA), docosahexaenoic (DHA), and omega-3. In contrast, GM was characterized by higher DO, pH, and monounsaturated fatty acids (MUFAs), specifically n-3 PUFA-docosapentaenoic (DPA), aligning with the homeoviscous adaptation theory. Despite higher contamination at the EB station, health risk assessments, including Target Hazard Quotient (THQ) and Target Cancer Risk (TCr), remained below established safety thresholds, confirming the fish's safety for human consumption. These findings underscore the efficacy of C. auratus as a bioindicator and demonstrate how site-specific physicochemical regimes govern the synergistic bioaccumulation of trace elements and remodeling of lipid compositions in coastal ecosystems.