Assessment of metal distribution patterns in loggerhead sea turtles: A comparative analysis based on sex and tissue type.

This study investigated the distribution patterns of 19 elements in various tissues and organs of stranded loggerhead sea turtles (Caretta caretta) from the Mediterranean coast of Turkey, with particular emphasis on sex-based differences in bioaccumulation. Tissue samples were collected from ten stranded individuals (five males, five females) between December 2021 and February 2022. Samples from muscle, heart, spleen, kidney, fat and liver tissues were analyzed using Inductively Coupled Plasma-Optical Emission Spectroscopy following microwave-assisted acid digestion. Elements were categorized into three functional groups: essential trace elements (Fe, Zn, Cu, Se, Co, Cr, Mg, Mo) possibly essential elements (Mn, Ni, V), and potentially toxic elements (Al, As, Ba, Cd, Hg, Pb, Sn, Sr). Statistical analysis using Aligned Rank Transformation ANOVA revealed significant tissue-specific accumulation patterns and sex-based differences. Essential trace elements showed highest concentrations in liver tissue, with Fe demonstrating the highest overall levels (median: 428.7 μg/kg). Male turtles exhibited significantly higher concentrations of Fe, Cu, Se, Ni, and Hg in specific tissues compared to females, while females showed elevated levels of Zn and Cd in kidney tissue. Correlation analysis identified strong positive relationships between several essential elements within liver tissue, suggesting potential shared accumulation or regulatory mechanisms. These results contribute to a deeper understanding of metal bioaccumulation mechanisms in endangered marine reptiles and offer essential baseline data for tracking metal pollution in Mediterranean marine environments. The detected sex-related variations emphasize the necessity of including sex as a critical biological factor in ecotoxicological research and conservation planning for sea turtle populations.