| Summary: | Purpose of the Study: Several studies have investigated the development of oxygen storage capacity in diving animals, but few studies have examined the development of oxygen store usage in these animals. Northern elephant seals (Mirounga angustirostris) are known to be air-breathing marine predators which exhibit continuous, long-duration, deep dives in the pelagic Pacific Ocean. Despite several previous attempts to calculate the duration allotted towards diving in an aerobic state, these animals consistently surpass this diving duration and repeatedly exhibit short surface intervals between dives. This information, suggests these animals are dramatically reducing their oxygen consumption (V02) during diving, compared to the V02 data used to predict aerobic dive durations. Additionally, little work has been done investigating the development of the "dive response" in marine mammals. This basic, physiological response to breath-holding and submersion allow individuals to achieve a greater reduction in V02• Information regarding the developmental aspects of this diving response in concert with an understanding on V02 reductions during a diving state can assist in understanding the energetic demands and processes these animals face. The purpose of this study is to determine the role of development on; a) the diving response and b) the ability to reduce V02 during breath-holds.Procedure: To determine the role of development on both the diving response and VOl during breath-holds, this study investigated V02 and blood-gas use during voluntary rest-associated apneas and voluntary submergences in 17 weaned northern elephant seal pups. Pups were either early in their weaning period (2 weeks post weaning) or late in their weaning period (7 weeks post weaning). Standard blood gas analysis and flow-through respirometry were used during both breath-hold types. Findings: When compared to early-weaned animals, there was a mean reduction of 17% in V02 during the breath-holds of older animals. This suggests a large role in the ...
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