Distribution and correlation of trace elements in Eurasian otters (Lutra lutra) from South Korea

As an apex predator, the Eurasian otter (Lutra lutra) encounters trace element pollutants in freshwater ecosystems. Our study assessed the accumulation of arsenic (As), cadmium (Cd), mercury (Hg), lead (Pb), selenium (Se), copper (Cu), manganese (Mn), and zinc (Zn) in the lung, liver, and kidney tissues of Eurasian otters collected from five regions in South Korea between 2018 and 2024. Comparisons with prior South Korean and European studies indicated regional variations in Se and Mn levels, while other trace element levels remained consistent. Overall concentrations were below known toxicity thresholds, indicating limited immediate risk, although persistent exposure may pose sublethal effects. Organ-specific distribution revealed that As, Cd, and Se accumulated primarily in the kidneys, whereas Hg, Pb, Cu, Mn, and Zn were highest in the liver. The lungs consistently showed the lowest concentrations. Positive correlations were observed between Cd, Hg, and Se, and between Pb and Cu. Age-related differences were identified, with adults exhibiting higher Cd, Hg, and Se levels, whereas juveniles had elevated Pb, Cu, and Zn concentrations. No sex-related differences were observed. These findings enhance understanding of trace element dynamics in Eurasian otters and provide updated insights into freshwater contamination in South Korea.