Oxygen Transport in the Leatherback Sea Turtle Dermochelys coriacea

We have investigated aerobic metabolism and blood O₂ transport properties of the leatherback sea turtle (Dermochelys coriacea). During nesting, at a body temperature of 29° C, resting ventilation (9.2 ± 1. 7 mL min⁻¹ kg⁻¹) and O₂ consumption (0. 25 ± 0.04 mL min⁻¹ kg⁻¹; three turtles) were slightly below values given for other sea turtles. Tidal volume was considerably smaller than in other turtles (4.0 ± 1.06 mL kg⁻¹) suggesting that Dermochelys has small lungs. Blood (measured in four turtles) had an extremely high Hb concentration (15. 6 ± 1.8 g dL⁻¹), hematocrit (39% ± 1.2%), and carried 21 ± 2.5 mL · dL⁻¹ blood, which exceeds the blood O₂ carrying capacity of other sea turtles and was similar to that of most mammals. Pectoral muscle myoglobin content, indicative of tissue O₂ stores, was 4.9 g dL⁻¹, twice that of other sea turtles. The P50, however, was similar to that of the loggerhead sea turtle: 31 and 40 mmHg for blood equilibrated with 2.2% (pH 7. 84) and 5% (pH 7.52) CO₂, respectively. We suggest that leatherback turtles rely on their enhanced blood and tissue O₂ stores rather than the lung O₂ store during deep dives.