The diving behaviour of green turtles at Ascension Island

• Published in: Animal behaviour Vol. 59; no. 3; pp. 577 - 586
• Main Authors: Hays, Graeme C., Adams, Colin R., Broderick, Annette C., Godley, Brendan J., Lucas, David J., Metcalfe, Julian D., Prior, Andrea A.
• Format: Journal Article
• Language: English
• Published: Kent Elsevier Ltd 01-03-2000; Elsevier; Harcourt Brace Jovanovich Ltd
• Subjects: Amphibia and reptilia; Animal behavior; Animal ethology; Biological and medical sciences; Chelonia mydas; Fundamental and applied biological sciences. Psychology; Marine; Psychology. Psychoanalysis. Psychiatry; Reptiles & amphibians; Vertebrata; Atlantic Ocean; Ascension Island; ASE, Atlantic, Ascension I; Nesting; Oxygen consumption; Duration; Breeding behavior; Chelonia mydas; Depth; Vertebrata; Chelonia; Breeding success; Diving; Strategy; Reptilia; Time budget; Field study
• ISSN: 0003-3472; 1095-8282
• DOI: 10.1006/anbe.1999.1326

For six green turtles, Chelonia mydas, that had nested on Ascension Island in the South Atlantic, we used time–depth recorders to examine their diving behaviour during the subsequent internesting interval (10–12 days). All the turtles performed dives where they remained at a fixed depth for a long period, surfaced briefly and then dived to the same depth again. It is generally believed these dive profiles are caused by the turtles resting on the sea bed. The maximum depth that turtles routinely reached on these resting dives was between 18 and 20m, with resting dives deeper than 20m being extremely rare. Resting dive duration increased significantly with deeper dives. From this relationship, and assuming that turtles with fully inflated lungs at the surface need to dive to 19m to achieve negative buoyancy, we estimated for two turtles that the oxygen consumption during resting dives was 0.016 and 0.020 litres O2/kg per h, respectively. This is similar to the value predicted from the allometric scaling relationship for the minimal oxygen consumption of turtles. We calculated that the energy conserved by resting during the internesting period may appreciably increase the reproductive output of females.