AL-HABSI, A. A.; ALKINDI, A.Y.A.; MAHMOUD, I. Y.; KHAN, H.; Sultan Qaboos Univ., Dept. of Biology, Al-Khod, Oman ; Sultan Qaboos Univ., Dept. of Biology, Al-Khod, Oman; Sultan Qaboos Univ., Dept. of Biology, Al-Khod, Oman; Canad. Mem. Chiropractic Coll., Toronto, Canada: Steroid levels in relationship to nesting phases in the green turtle, Chelonia mydas at Ras Al-Hadd Reserve-Oman.

Circulating sex steroids levels of estradiol, testosterone and progesterone were monitored in the green turtle Chelonia mydas during different phases of nesting which included emerging from the sea, digging the body or the nest chamber, abandonment related to nest selection; and after nest completion (post-nesting) which involved oviposition and burying. The study was conducted at Ras Al-Hadd Reserve-Oman (1999-2002). Blood samples for the hormone study were taken from the cervical sinuses. Progesterone levels were significantly higher in turtles that had completed their nesting than in their emerging, excavation and abandonment phases. It is possible that ovulation may take place shortly after oviposition as luteinizing hormone (LH) begins to rise earlier than has been previously reported in other studies, and thus triggering ovulation and corpora lutea formation, which may cause a dramatic rise in progesterone levels. There are no significant differences in progesterone levels between nest digging, emerging from the sea, or nest abandonment. Testosterone levels were low throughout nesting, and there was no significant difference between the nesting phases. Estradiol levels were below the detectable levels in all of the phases. Monitoring the steroid levels at different phases of nesting may be of value in understanding the significance of hormone dynamics during the nesting process.