AB 8:237-245 (2010)  -  DOI: https://doi.org/10.3354/ab00216

Oxygen store depletion and the aerobic dive limit in emperor penguins

P. J. Ponganis*, J. U. Meir, C. L. Williams

Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093–0204, USA

ABSTRACT: The aerobic dive limit (ADL), dive duration associated with the onset of post-dive blood lactate elevation, has been widely used in the interpretation of diving physiology and diving behavior. However, its physiological basis is incompletely understood, and in most studies, ADLs are simply calculated with an O2 store/O2 consumption formula. To better understand the ADL, research has been conducted on emperor penguins diving at an isolated dive hole. This work has revealed that O2 stores are greater than previously estimated, and that the rate of depletion of those O2 stores appears to be regulated primarily through a diving bradycardia and the efficiency of swimming. Blood and respiratory O2 stores are not depleted at the 5.6 min ADL determined by post-dive blood lactate measurements. It is hypothesized that muscle, isolated from the circulation during a dive, is the primary source of lactate accumulation. To predict this 5.6 min ADL for these shallow dives at the isolated dive hole with the classic O2 store/O2 consumption formula, an O2 consumption rate of 2× the predicted metabolic rate of a penguin at rest is required. In contrast, if the formula is used to calculate an ADL that is defined as the time for all consumable O2 stores to be depleted, then a 23.1 min dive, in which final venous partial pressure of oxygen (PO2) was 6 mm Hg (0.8 kPa), represents such a maximum limit and demonstrates that an O2 consumption rate of about 0.5× the predicted rate of an emperor penguin at rest is required in the formula.

KEY WORDS: Aerobic dive limit · ADL · Emperor penguins · Heart rate · Lactate · Oxygen · Temperature

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Cite this article as: Ponganis PJ, Meir JU, Williams CL (2010) Oxygen store depletion and the aerobic dive limit in emperor penguins. Aquat Biol 8:237-245. https://doi.org/10.3354/ab00216

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