Göksu Deltası’ndaki Deniz Kaplumbağalarının Üreme Ekolojisi Üzerine Araştırmalar

Abstract

The aim of this thesis is to present the nesting dynamics of sea turtles in the Göksu Delta and the environmental factors affecting them in detail. Basic information about the nests of Caretta caretta (Linnaeus, 1758) and Chelonia mydas (Linnaeus, 1758) species, predation rates, success rates of relocated and original nests, nest depth and distance to the sea were analysed in detail in this study. In particular, the effects of factors such as nesting success rates of Caretta caretta individuals, predation pressures and temperature were evaluated. The data obtained also include the temperature profiles of the nests and the effects of these profiles on sex ratios.

Within the scope of this study, which was carried out in Göksu Delta, one of the important nesting beaches in Turkey, the breeding activities of sea turtles in 2022 were analysed. As a result of the studies carried out on the beach named 760 in the Göksu Delta during the breeding season, a total of 80 nests were identified, 70 of which were Caretta carretta nests and 10 Chelonia mydas nests.

A total of 6270 eggs were detected; 861 of them were predated, 152 were damaged, 1962 had no development and 704 had started but not completed embryonic development. Only 35% of the total eggs could reach the sea with development. In addition, temperature sensors were placed in 6 Caretta caretta nests and measurements made during the incubation period showed that the average hatching temperature was 31.3 °C, nest success was 70% and 85% of the sex distribution was estimated to be female. Within the scope of the thesis, the nesting activities of Caretta caretta and the factors affecting them were analysed in detail.

Out of a total of 80 nests, 25 nests were found to be predated and only 5 of these nests were found to continue nest development. In 20 nests, all eggs were destroyed by coyotes or dogs. Although all nests were caged as soon as possible, predation was observed in 31.2% of the nests, especially in the nests built in July.

A total of 22 nests, 20 Caretta caretta nests and 2 Chelonia mydas nests, were moved to a safer location to protect them from various environmental pressures such as flooding. The mean success rates of the original and relocated nests were analysed but no significant difference was found. Nevertheless, hatchlings from 12 of the relocated nests, which would have been subjected to serious pressures if not moved, reached the sea. Within the scope of sea turtle marking studies, a total of 11 individuals, 9 Caretta caretta and 2 Chelonia mydas, were marked during the night surveys carried out during the nesting period. In addition, one individual that had been marked in previous years' studies was recaptured and the length and width of the carapace of a total of 12 individuals were measured.

This research provides important information for the conservation and management of sea turtle nesting areas and provides a scientific basis for future conservation strategies.