O2 store management in diving emperor penguins

• Published in: Journal of Experimental Biology
• Main Authors: Ponganis, P. J., Stockard, T. K., Meir, J. U., Williams, C. L., Ponganis, K. V., Howard, R.
• Format: Text
• Language: English
• Published: Company of Biologists 2009
• Subjects: Research Article; McMurdo Sound; Antarc*; Antarctica; Aptenodytes forsteri; Emperor penguins; Sea ice
• Online Access: http://jeb.biologists.org/cgi/content/short/212/2/217; https://doi.org/10.1242/jeb.026096

In order to further define O 2 store utilization during dives and understand the physiological basis of the aerobic dive limit (ADL, dive duration associated with the onset of post-dive blood lactate accumulation), emperor penguins ( Aptenodytes forsteri ) were equipped with either a blood partial pressure of oxygen ( P O 2 ) recorder or a blood sampler while they were diving at an isolated dive hole in the sea ice of McMurdo Sound, Antarctica. Arterial P O 2 profiles (57 dives) revealed that (a) pre-dive P O 2 was greater than that at rest, (b) P O 2 transiently increased during descent and (c) post-dive P O 2 reached that at rest in 1.92±1.89 min ( N =53). Venous P O 2 profiles (130 dives) revealed that (a) pre-dive venous P O 2 was greater than that at rest prior to 61% of dives, (b) in 90% of dives venous P O 2 transiently increased with a mean maximum P O 2 of 53±18 mmHg and a mean increase in P O 2 of 11±12 mmHg, (c) in 78% of dives, this peak venous P O 2 occurred within the first 3 min, and (d) post-dive venous P O 2 reached that at rest within 2.23±2.64 min ( N =84). Arterial and venous P O 2 values in blood samples collected 1–3 min into dives were greater than or near to the respective values at rest. Blood lactate concentration was less than 2 mmol l–1 as far as 10.5 min into dives, well beyond the known ADL of 5.6 min. Mean arterial and venous P N 2 of samples collected at 20–37 m depth were 2.5 times those at the surface, both being 2.1±0.7 atmospheres absolute (ATA; N =3 each), and were not significantly different. These findings are consistent with the maintenance of gas exchange during dives (elevated arterial and venous P O 2 and P N 2 during dives), muscle ischemia during dives (elevated venous P O 2 , lack of lactate washout into blood during dives), and arterio-venous shunting of blood both during the surface period (venous P O 2 greater than that at rest) and during dives (arterialized venous P O 2 values during descent, equivalent arterial and venous P N 2 values during dives). These three ...