Variability in maternal transfer efficiency of trace elements in green turtles (Chelonia mydas)

Abstract

The transfer of trace elements (TEs) from female sea turtles to their eggs is crucial in providing essential nutrition for embryonic development, while also posing a potential risk of pollutant exposure. This study aimed to quantify the concentrations of TEs in the claws and epidermis of nesting females, as well as in egg contents and embryos, and to investigate the migration of TEs during the maternal transfer in green turtles. The findings revealed that the maternal transfer coefficients for essential elements including Fe, Cu, and Zn (excluding those derived from accumulated tissue) ranged from 1.0 to 10.0, while the coefficients for non-essential elements such as Cd, As, and Hg were found to be below 1.0. During embryonic development, the migration coefficients of Fe, Mn, Ni, Zn and Sr exhibited a progressive increase, reaching their peak at stages 27–31 with values of 9.14 for Fe, 6.52 for Mn, 6.34 for Ni, 2.90 for Zn, and 2.66 for Sr. This indicates a high efficiency in the assimilation of these elements. Conversely, the migration coefficients of Cu, Se, Cd, Pb, and Hg declined rapidly after peaking at stages 19–22. Additionally, the kidneys of final-stage embryos and hatchlings exhibited significantly higher levels of non-essential elements compared to other tissues, while the liver displayed higher concentrations of Cu. These results suggest that early-stage embryos are particularly vulnerable to the adverse effects of non-essential or excessive essential elements, and as well, they indicate the presence of potential detoxification mechanisms that may develop following tissue and organ formation, which warrants further investigation.