ALKINDI, Abdulaziz Y.A.; MAHMOUD, Ibrahim Y.; BATCHELOR, Christopher; KHAN, Hamid R.: Circulating steroid hormone levels during high and low density nesting periods in the Green Turtle, Chelonia mydas in Oman

Plasma steroid levels (progesterone, testosterone and estradiol) were monitored during high (June-October) and low (November-May)density nesting periods at Ras Al-Hadd, Oman. The examined turtles had either completed their nesting phases with successful oviposition or had incomplete nesting phases without oviposition. Both groups had made one or several attempts in choosing their nest sites as they spent 1.5 – 4.5 hr on the nesting ground before returning to the sea. There was no significant difference in progesterone values between the two periods while testosterone values were significantly higher (P<0.05) in high density over the low density. The estradiol values were either undetectable or very low during both periods. Progesterone and testosterone were highly correlated in each period and between the two periods. Blood samples were collected from the cervical sinuses and assayed by radioimmunoassay technique. The overall stable steroid levels may indicate their vital role in ovarian growth and nesting behavior.