Size- and month-dependent bioaccumulation of trace elements and toxic metals in atlantic bonito (Sarda sarda, Bloch, 1793): Implications for nutritional security and environmental health

Background: Trace elements play dual roles in marine ecosystems and human health, acting as trace elements (e. g., Cu, Fe, Se, Zn) or toxic contaminants (e.g., Hg, As). This study investigates the bioaccumulation of 14 trace elements in Sarda sarda, a commercially and ecologically important species, to evaluate size- and seasondependent trends and their implications for environmental health and nutritional security. Methods: This study investigated the bioaccumulation of heavy metals (mercury (Hg), lead (Pb), cadmium (Cd), chromium (Cr), nickel (Ni)) and trace elements (arsenic (As), zinc (Zn), iron (Fe), selenium (Se), copper (Cu), manganese (Mn), aluminum (Al), boron (B), lithium (Li)) in Sarda sarda individuals categorized by size classes (small, medium, large, based on body length and weight) sampled monthly from the Sinop fishery, Turkey, in September, October, and November 2023. Metal concentrations were quantified in muscle tissue using inductively coupled plasma mass spectrometry (ICP-MS) with strict quality assurance protocols. Health risk indices (EDI, THQ, TTHQ, CRR, ADC, CDR, HBVSe) were calculated to assess dietary exposure risks. Results size-dependent trends: Hg and As levels increased significantly with fish size (p < 0.05), reflecting trophic magnification, while Li exhibited an inverse relationship, with higher concentrations in smaller fish. Seasonal dynamics: Cu, Mn, and Se peaked in September. Pb and Cd were undetectable (<0.005 mg/kg), indicating low anthropogenic contamination. Health risks: All metals fell below international safety thresholds. Conclusion: This study highlights the dual influence of biological (fish size, trophic position) and environmental (seasonal pollutant fluxes) factors on trace element bioaccumulation in Sarda sarda. While current levels pose minimal health risks, proactive monitoring is essential to address emerging contaminants and ensure sustainable fisheries management. These findings provide a template for adaptive monitoring frameworks in transitional marine ecosystems.