Investigation of the effects of sand particle size on the suitability of nesting habitats of hawksbill turtle (Eretmochelys imbricata; Linnaeus, 1766) in the Persian Gulf

Hawksbill turtles (Eretmochelys imbricata) are one of the seven remaining species of sea turtles in the world that are classified as endangered in the IUCN Red List due to their long-term use. Nest site selection is one of the most important behaviors in reproductive females. Because the environment around the nest affects the survival of the hatchlings. Sands were collected from eight nesting beaches in the Persian Gulf from three depths. After drying the samples in the open air, 100 gr of the dried sample was weighed separately for each depth. ASTM standard sieves (No.: 4-200) were used to determine the particle size distribution. Finally, the contents of each sieve were collected and the statistical parameters were calculated using the GRADISTAT program. The sand texture in Hormoz and Ommolkaram Islands was Gravelly and in other areas it was Slightly Gravelly. Particle size in all important points of nesting areas was less than 1000 μm with an average of 581.6±171.4. The lowest particle diameter in Nayband Bay was 284.9 μm and the highest in Ommolkaram Island was 856.4 μm. Based on the results of the present study, the grain size and origin of sand particles in the Persian Gulf islands, including oyster shells, coral and gravel, indicate high diversity in the structure of nesting hawksbill turtle populations in Iran. In the Persian Gulf hawksbill turtle, the size of particles as a feature does not have a significant effect on the tendency to dig nests.