Birgitte McDonald Moss Landing Marine Laboratory
It is essential to understand the oxygen management of marine mammals if we are to interpret and understand their foraging ecology, the limits of dive performance, and their ability to adapt to environmental change and disturbance. During forced submersion, severe bradycardia (heart rate reduced to below resting) results in isolation of muscle and peripheral organs from blood flow, thereby conserving oxygen for the heart and brain. However, with the development of bio-loggers, studies on trained and freely diving animals indicate that this dive response is much more variable and complex than initially proposed. I will present my research investigating the dive response and oxygen management strategies in wild California sea lions and captive harbor porpoises using bio-loggers that measured blood oxygen, heart rate, and dive behavior during natural dives. I will discuss how sea lions and porpoise are able to optimize the amount of oxygen they take on a dive, and how they manage oxygen during dives of different depths, duration, and activity levels.