Heart rates of emperor penguins diving at sea: implications for oxygen store management

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 496:85-98 (2014) - DOI: https://doi.org/10.3354/meps10592 Theme Section: Tracking fitness in marine vertebrates Heart rates of emperor penguins diving at sea: implications for oxygen store management Alexandra K. Wright*, Katherine V. Ponganis, Birgitte I. McDonald, Paul J. Ponganis Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093-0204, USA *Corresponding author: awright@ucsd.edu ABSTRACT: Heart rate (ƒH) contributes to control of blood oxygen (O2) depletion through regulation of the magnitude of pulmonary gas exchange and of peripheral blood flow in diving vertebrates such as penguins. Therefore, we measured ƒH during foraging trip dives of emperor penguins Aptenodytes forsteri equipped with digital electrocardiogram (ECG) recorders and time depth recorders (TDRs). Median dive ƒH (total heartbeats/duration, 64 beats min-1) was higher than resting ƒH (56 beats min-1) and was negatively related to dive duration. Median dive ƒH in dives greater than the 5.6 min aerobic dive limit (ADL; dive duration associated with the onset of a net accumulation of lactic acid above resting levels) was significantly less than the median dive ƒH of dives less than the ADL (58 vs. 66 beats min-1). ƒH profile patterns differed between shallow (<50 m) and deep dives (>250 m), with values usually declining to levels near resting ƒH in shallow, short-duration dives, and to levels as low as 10 beats min-1 during the deepest segments of deep dives. The total number of heartbeats in a dive was variable in shallow dives and consistently high in deep dives. A true bradycardia (ƒH below resting levels) during segments of 31% of shallow and deep dives of emperor penguins is consistent with reliance on myoglobin-bound O2 stores for aerobic muscle metabolism that is especially accentuated during the severe bradycardias of deep dives. Although ƒH is low during the deepest segments of deep dives, the total number and distribution of heartbeats in deep, long dives suggest that pulmonary gas exchange and peripheral blood flow primarily occur at shallow depths. KEY WORDS: Aerobic dive limit · Diving physiology · Electrocardiogram · ECG · Emperor penguin · Gas exchange · Heart rate · Oxygen store management · Peripheral perfusion Full text in pdf format PreviousNextCite this article as: Wright AK, Ponganis KV, McDonald BI, Ponganis PJ (2014) Heart rates of emperor penguins diving at sea: implications for oxygen store management. Mar Ecol Prog Ser 496:85-98. https://doi.org/10.3354/meps10592 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 496. Online publication date: January 27, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.