Trace Elements and Persistent Organic Pollutants in Unhatched Loggerhead Turtle Eggs from an Emerging Nesting Site along the Southwestern Coasts of Italy, Western Mediterranean Sea

Simple Summary The western Mediterranean is an important nesting area for sea turtles, but at the same time, a hotspot for human-induced threats. Persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs), as well as toxic and potentially toxic elements, are insidiously and ubiquitously distributed in the marine environment. These contaminants can accumulate in tissues, organs, and fluids of loggerhead turtle Caretta caretta, and maternal transfer of these chemicals via egg yolk during reproduction may affect the reproductive success of nesting populations. In this study, the levels of organochlorine pesticides, six indicator polychlorinated biphenyls, and trace elements were measured in unhatched eggs of C. caretta. With the exception of organochlorine pesticides, these contaminants were detected in all samples tested, demonstrating the transfer of chemicals from mothers to their progeny. However, their concentrations did not influence reproductive parameters. This study confirms the use of turtle eggs as a pollution monitoring tool and contributes to the scientific knowledge on the effects of environmental changes and human activities on sea turtle populations needed for the conservation of the species. Marine pollution is one of the major threats affecting loggerhead turtles, which due to their long life span, highly migratory behavior, and carnivorous diet, may be exposed to elevated levels of toxic elements throughout their life. The transfer of chemicals from mothers to their offspring is of particular conservation concern because it may affect embryonic development and hatching success. In this study, the concentrations of 16 toxic and potentially toxic trace elements, 6 indicator polychlorinated biphenyls (PCBs), and organochlorine pesticide residues (OCPs) were determined in 138 eggs from 46 loggerhead turtle nests laid during the 2021 nesting season in Campania, Italy, western Mediterranean Sea. The possible impact of pollutant levels on hatching success and early embryonic death was also investigated. Trace element analysis was performed using an ICP-MS, except for mercury, which was determined using a Direct Mercury Analyzer (R) (DMA). PCBs and OCPs were analyzed with high-resolution gas chromatography coupled with high-resolution mass spectrometry (HRGC-HRMS) and gas chromatography tandem quadrupole mass spectrometry GC-MS /MS, respectively. The concentrations of essential elements in the eggs were higher than those of non-essential elements. In addition, the highly chlorinated PCBs (153, 138, and 180) contributed the most to the total PCBs, while OCPs were not detected. No correlations were found between contaminant concentrations and reproductive parameters (hatching success and no obvious embryos). The results obtained suggest that the levels of contaminants found in the eggs do not affect the reproductive success of the species in the study area.

Automated summary

This study investigated the marine pollution in the nesting area of sea turtles in the western Mediterranean. It found that mother turtles transfer contaminants to their unhatched eggs, but the concentrations of these chemicals do not affect reproductive success. The study confirms the use of turtle eggs as a pollution monitoring tool and contributes to the scientific knowledge needed for the conservation of sea turtle populations.