Ecological and ecotoxicological study on the nesting sea turtle (Caretta caretta) on Patara beach

In this study, the identification of sporadic nesting sites of the Caretta caretta sea turtles outside the main nesting beaches in the western part of Antalya was carried out. During the 2021 and 2022 sea turtle breeding seasons, a total of 112 emergences of C. caretta were recorded on Faselis Beach, Kazanova Beach, Korsan Bay, and Kaputaş Beach, with 54 of them resulting in nests. When these findings were combined with data from the literature, it was estimated that sporadic nesting beaches contribute approximately 1-2% to the total number of C. caretta nests in Turkey. Additionally, at the scale of Turkey and the Mediterranean, the effects of climate variables on the reproductive biology of sea turtles nesting on Patara Beach, as well as the impacts of certain chemical pollutants accumulated in the blood tissues of nesting sea turtles on their reproductive outputs, were investigated for the first time. In this context, the reproductive biology of Caretta caretta was compared with climate variables throughout the 2019–2023 breeding seasons on Patara Beach. The findings revealed that atmospheric temperature and relative humidity affected nest content parameters, while sea surface temperature, atmospheric temperature, relative humidity, and precipitation were linked to the emergence patterns of turtles. Additionally, the increase in atmospheric temperature caused minor changes in the nesting timing of turtles, leading to temporal shifts in their phenology, as well as influencing incubation duration and hatchling sex ratios. Finally, blood samples collected from nesting turtles were analyzed for metal concentrations (Al, As, Ca, Cd, Cr, Cu, Fe, Hg, Mg, Ni, Pb, Zn) and polycyclic aromatic hydrocarbons (benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, and chrysene), as well as erythrocyte nucleus anomaly frequencies. The relationships between the detected chemical pollutants, erythrocyte nucleus anomaly frequencies, and all nest content parameters were examined, and key variables influencing hatching success were identified.