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Determinants of the Aerobic Dive Limit of Weddell Seals: Analysis of Diving Metabolic Rates, Postdive End Tidal P o 2 's, and Blood and Muscle Oxygen Stores

1993; University of Chicago Press; Volume: 66; Issue: 5 Linguagem: Inglês

10.1086/physzool.66.5.30163821

1937-4267

Paul J. Ponganis, Gerald L. Kooyman, Michael A. Castellini,

Physiological and biochemical adaptations

The mean aerobic dive limit (ADL) for Weddell seals was calculated from data collected on diving metabolic rates (V̇o2) and blood and muscle O₂ stores. Mean diving V̇o2 of adult seals during predominantly exploratory dive patterns was 4.5 mL O2 kg−1 min−1; mean V̇o2 of a subadult seal engaged in foraging dive bouts was 8.5 mL O2 kg−1 min−1. The adult value was 30% greater than that used in past ADL calculations. Mean plasma volume was 7% body mass (BM); blood volume calculated with the highest hematocrit (Hct) observed (66) was 21% BM. Hemoglobin concentration at such an Hct was 26% by weight. End tidal Po2 (pre-and postdive) justified the use of 95% and 20% arterial O2 saturations in the blood O2 store calculation. Total blood O2 stores were 50% greater than those used in past ADL calculations. Mean myoglobin concentration (5.4% by weight) and more recent anatomical estimates of muscle mass yielded a 35% increase in muscle O2 stores. The mean estimated ADL for a 450-kg seal calculated with these new data was 19.1 min, 2.3 min greater than in past calculations and only 1 min less than the 20-min inflection point of the curve of dive duration versus postdive lactic acid appearance. For the subadult engaged in foraging dives, the mean estimated ADL was about 9 min, again quite similar to past ADL calculations.