Effects of Temperature on Nest Success of Hawksbill Sea Turtles, Eretmochelys imbricata (Linnaeus, 1766), in the Persian Gulf Islands

Aims: Temperature is one of the factors that can affect the survival of sea turtle hatchlings. As a critically endangered species, the Hawksbill sea turtle nests in several Iranian islands including Kish and Qeshm. Few studies have so far been conducted on the effect of temperature on the nesting success of this species in the Persian Gulf. The objective of this study is to investigate the effects of temperature on the survival of turtle hatchlings in two nesting areas. Materials Methods: The temperature of the sand and the nest was recorded and analyzed using thermochron data loggers for several consecutive years from 2019 to 2021 in four nesting areas (Qeshm, Kish, Nakhiloo, and Nayband Bay) from the beginning of the nesting season until the emergence of hatchlings. Three factors of nest success including hatching success (percentage of hatchlings that hatch from the eggs), mortality (percentage of dead hatchings), and emergence success (percentage of hatchlings that emerge from the nest) were chosen as indicators to evaluate nest success in Kish and Qeshm Islands. Findings: The lowest annual mean sand temperature was related to Kish Island. The annual mean nest temperature in Kish and Qeshm Islands showed a significant difference. In Kish Islands, the annual mean temperature of the nests was at a level higher than the thermal tolerance threshold (33 to 35°C) for less than five days. Examining the success of the nests showed Kish has a higher mean hatching success than Qeshm, but this result does not hold true for the other two criteria. Conclusion: Although checking the temperature of the sand and the nest can provide useful information regarding the survival of the turtle hatchlings and the implementation of protection decisions, investigating other factors besides temperature can be helpful as well.