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New insights into the cardiorespiratory physiology of weaned southern elephant seals (Mirounga leonina)
Citation
Cummings, CR and Lea, MA and Morrice, MG and Wotherspoon, S and Hindell, MA, New insights into the cardiorespiratory physiology of weaned southern elephant seals (Mirounga leonina), Conservation Physiology, 3, (1) Article cov049. ISSN 2051-1434 (2015) [Refereed Article]
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Copyright Statement
Copyright 2015 The Authors. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/
DOI: doi:10.1093/conphys/cov049
Abstract
Southern elephant seal (Mirounga leonina) pups must strike a balance between conserving energy during their post-weaning fast and simultaneously developing diving
abilities to attain nutritional independence. Little is known about environmental influences on cardiorespiratory patterns,
hence energy use, throughout the 6 week fast. Continuous heart rates were recorded for free-ranging, newly weaned southern
elephant seals using heart rate time–depth recorders for 5–9 days at Sub-Antarctic Macquarie Island, during October 1994 (n = 1), 1995 (n = 4) and 1996 (n = 1). Daytime observations of respiration and behaviour were made throughout. We present the first instance of synchronous
heart rate traces recorded simultaneously for individual weaners. Generalized additive models revealed that a sinusoidal pattern
of diurnal heart rate elevation and nocturnal depression was evident in all seals and, on at least one occasion, a conspicuous
break in this pattern coincided with an extreme cold weather event. Seals in this study were capable of considerable cardiorespiratory
control and regularly demonstrated bradycardia during periods of resting apnoea. Apnoeic duration ranged from 33 to 291 s
(mean 134 s). Apnoeic heart rates (mean 67 ± 15 beats min−1, range 40–114 beats min−1) were on average 19.7% lower than those exhibited during periods of eupnoea (mean 83 ± 15 beats min−1, range 44–124 beats min−1). The early development of the cardiorespiratory response is characterized by arrhythmic heart and respiration rates. The
strong temporal patterns observed are being driven by the opposing requirements of maximizing time spent fasting in order
to develop diving capabilities and of maximizing departure mass. This pilot study has highlighted a potentially large effect
of ambient weather conditions on newly weaned southern elephant seal cardiorespiratory activity. Given the increasing westerlies
and more erratic and increasing storminess associated with the Southern Annular Mode predicted in the Southern Ocean, the
patterns observed here warrant further investigation.
Item Details
| Item Type: | Refereed Article |
|---|---|
| Keywords: | chronobiology, circadian rhythms, generalized additive models, threshold physiological response |
| Research Division: | Biological Sciences |
| Research Group: | Zoology |
| Research Field: | Zoology not elsewhere classified |
| Objective Division: | Environmental Management |
| Objective Group: | Management of Antarctic and Southern Ocean environments |
| Objective Field: | Biodiversity in Antarctic and Southern Ocean environments |
| UTAS Author: | Cummings, CR (Ms Cloe Cummings) |
| UTAS Author: | Lea, MA (Professor Mary-Anne Lea) |
| UTAS Author: | Wotherspoon, S (Dr Simon Wotherspoon) |
| UTAS Author: | Hindell, MA (Professor Mark Hindell) |
| ID Code: | 106445 |
| Year Published: | 2015 |
| Deposited By: | IMAS Research and Education Centre |
| Deposited On: | 2016-02-10 |
| Last Modified: | 2018-03-17 |
| Downloads: | 191 View Download Statistics |
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