EMPEROR PENGUIN OXYGEN-CONSUMPTION, HEART-RATE AND PLASMA LACTATE LEVELS DURING GRADED SWIMMING EXERCISE

Oxygen consumption (V-O2), heart rate and blood chemistry were measure d in four emperor penguins, Aptenodytes forsteri (Gray), during graded swimming exercise. The maximum V-O2, obtained, 52ml O-2 kg(-1) min(-1 ), was 7.8 times the measured resting V-O2 of 6.7 ml O-2 kg(-1) min(-1 ) and 9.1 times the predicted resting V-O2. As the swimming effort ros e, a linear increase in surface and submerged heart rates (fH) occurre d. The highest average maximum surface and submersion heart rates of a ny bird were 213 and 210 beats min(-1), respectively. No increase in p lasma lactate concentrations occurred until V-O2 was greater than 25 m l O-2 kg(-1) min(-1). At the highest V-O2 values measured, plasma lact ate concentration reached 9.4 mmol l(-1). In comparison with other ani mals of approximately the same mass, the aerobic capacity of the emper or penguin is less than those of the emu and dog but about the same as those of the seal, sea lion and domestic goat. For aquatic animals, a low aerobic capacity seems to be consistent with the needs of parsimo nious oxygen utilization while breath-holding.