Blood Oxygen Depletion in Diving California Sea Lions: How Close to the Limit.

摘要

The management and depletion of O2 stores underlie the dive capacities of marine mammals and are fundamental to the concept of an aerobic dive limit (ADL, dive duration associated with the onset of post-dive blood accumulation). The ADL, which is often calculated (cADL) on the basis of total body O2 stores and an estimated diving metabolic rate, has become an essential concept in the interpretation of diving behavior and foraging ecology (Kooyman and Ponganis 1998); however, the actual rate and magnitude of O2 store depletion during dives has not been determined in any otariid. This project documented the rate and magnitude of blood O2 store depletion during diving in California sea lions, and this information will be used to develop an experimental approach to assess the aerobic dive limit (ADL) and O2 store depletion in this and other otariid species. The specific objectives of this project are: 1) Document venous and arterial PO2 profiles in lactating California sea lions while diving during foraging trips to sea, 2) Characterize the O2-hemoglobin (Hb) dissociation curve of sea lion Hb, 3) Convert the PO2 profiles into % Hb saturation (SO2) profiles with the dissociation curve, and then calculate the rate and magnitude of blood oxygen depletion, and 4) Refine vascular access techniques to allow future investigations of blood N2 kinetics, changes in blood pH, PCO2, PO2 and lactate during dives, and stress responses to captivity, training, and/or sound exposure.