Changes in plasma levels of adrenaline, noradrenaline, glucose, lactate and CO 2 in the green turtle, Chelonia mydas, during peak period of nesting A.Y.A. AlKindi * , A.A. Al-Habsi, I.Y. Mahmoud Department of Biology, College of Science, Sultan Qaboos University, 123, Al-Khod, Muscat, Oman Received 12 March 2007; revised 14 September 2007; accepted 15 September 2007 Available online 21 September 2007 Abstract Plasma concentrations of stress hormones [adrenaline (ADR), noradrenaline (NR)], lactate, glucose and CO 2 were monitored during peak nesting period (May–October) at different phases of nesting in the green turtle, Chelonia mydas. These include, emergence from sea, excavating body and nest chambers, oviposition, covering and camouflaging the nest and then returning to sea. Turtles that completed all phases of nesting including oviposition before returning to sea were considered ‘‘successful’’ turtles, while those that completed all phases but failed to lay their eggs were ‘‘unsuccessful’’. Blood samples were taken from the cervical sinus within 5 min of capture to avoid stress due to handling. The turtles were usually sampled for blood between 20:00 and 1:00 h of nesting time to ensure uniformity in the sam- pling. Plasma ADR and NR values were highly significant (P < 0.001) in successful turtles over emergence, excavating and unsuccessful turtles. Plasma glucose levels remained stable throughout the nesting phases while lactate levels were significantly higher in successful turtles over the other phases (P < 0.05) which signifies anaerobic metabolism during nesting. Plasma CO 2 values were negatively corre- lated with ADR and NR (r = À0.258, P = 0.03; r = À0.304, P = 0.010), respectively. Hematocrit was significantly higher in successful phase (P < 0.05) compared to other phases, and this may signify a higher degree of stress in successful turtles. Body temperature were significantly lower (P < 0.005) in the excavating phase compared to the other three phases. Overall, body temperatures were lower than sand temperatures around the nest, which may indicate a behavioral thermoregulation used by the turtles during nesting. This informa- tion will be of value to the ongoing conservation program at Ras Al-Hadd Reserve in the Sultanate of Oman. Ó 2008 Published by Elsevier Inc. Keywords: Catecholamine; Nesting; Sea turtles 1. Introduction Female sea turtles go through exhaustive and difficult physical activities during nesting phases that include emerging from the sea and crawling to a selected nest site, excavating the nest, ovipositing, burying the eggs, and crawling back to sea (AlKindi et al., 2003; Hendrickson, 1982; Bustard, 1973; Bustard and Greenham, 1969). Before choosing a favorable nesting site to lay their eggs, sea tur- tles frequently investigate and then abandon several sites because of unfavorable conditions, such as lack of sand moisture, sand obstacles or disturbance. This is the case in green turtles where, nesting can be a long stressful ordeal and sometimes lasts for several hours, depending on the number of nest abandonments during excavation (AlKindi et al., 2003). It is well documented that in reptiles, exhaustive exercise triggers the release of catecholamines (adrenaline ADR, noradrenaline NR) into the bloodstream to accelerate ven- tilation, heart rate, glycogen utilization, and oxygen uptake (AlKindi et al., 2003; Gleeson et al., 1993). Moreover, sea turtles, like some lung-breathing reptiles, ventilate intermit- tently (Comeau and Hicks, 1994; Shelton and Burggren, 1976; Wasser and Jackson, 1991). Thus, after a burst of strenuous exercise (about 30–60 s) during the nesting 0016-6480/$ - see front matter Ó 2008 Published by Elsevier Inc. doi:10.1016/j.ygcen.2007.09.012 * Corresponding author. Fax: +968 24413415. E-mail address: aakindy@squ.edu.om (A.Y.A. AlKindi). www.elsevier.com/locate/ygcen Available online at www.sciencedirect.com General and Comparative Endocrinology 155 (2008) 581–588