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The metabolic cost of subcutaneous and abdominal rewarming in king penguins after long-term immersion in cold water

Lewden, Agnès ; Bonnet, Batshéva and Nord, Andreas LU (2020) In Journal of Thermal Biology 91.
Abstract
Marine endotherms in the polar regions face a formidable thermal challenge when swimming in cold water. Hence, they use morphological (fat, blubber) adjustment and peripheral vasoconstriction to reduce demands for heat production in water. The animals then regain normothermia when resting ashore. In the king penguin (Aptenodytes patagonicus) metabolic rate is lower in fed than in fasted individuals during subsequent rewarming on land. This has been suggested to be a consequence of diversion of blood flow to the splanchnic region in fed birds, which reduces peripheral temperatures. However, peripheral temperatures during recovery have never been investigated in birds with different nutritional status. The aim of this study was, therefore,... (More)
Marine endotherms in the polar regions face a formidable thermal challenge when swimming in cold water. Hence, they use morphological (fat, blubber) adjustment and peripheral vasoconstriction to reduce demands for heat production in water. The animals then regain normothermia when resting ashore. In the king penguin (Aptenodytes patagonicus) metabolic rate is lower in fed than in fasted individuals during subsequent rewarming on land. This has been suggested to be a consequence of diversion of blood flow to the splanchnic region in fed birds, which reduces peripheral temperatures. However, peripheral temperatures during recovery have never been investigated in birds with different nutritional status. The aim of this study was, therefore, to measure subcutaneous and abdominal temperatures during the rewarming phase on land in fasted and fed king penguins, and investigate to which extent any different rewarming were reflected in recovery metabolic rate (MRR) after long term immersion in cold water. We hypothesized that fed individuals would have a slower increase of subcutaneous temperatures compared to fasted penguins, and a correspondingly lower MRR. Subcutaneous tissues reached normothermia after 24.15 (back) and 21.36 min (flank), which was twice as fast as in the abdomen (46.82 min). However, recovery time was not affected by nutritional condition. MRR during global rewarming (4.56 ± 0.42 W kg−1) was twice as high as resting metabolic rate (RMR; 2.16 ± 0.59 W kg−1). However, MRR was not dependent on feeding status and was significantly elevated above RMR only until subcutaneous temperature had recovered. Contrary to our prediction, fed individuals did not reduce the subcutaneous circulation compared to fasted penguins and did not show any changes in MRR during subsequent recovery. It seems likely that lower metabolic rate in fed king penguins on land reported in other studies might not have been caused primarily by increased circulation to the visceral organs. (Less)
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author
; and
organization
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type
Contribution to journal
publication status
published
subject
keywords
thermoregulation, penguin, bird, heterothermy, metabolic rate, polar, body temperature
in
Journal of Thermal Biology
volume
91
article number
102638
publisher
Elsevier
external identifiers
  • pmid:32716880
  • scopus:85087765936
ISSN
0306-4565
DOI
10.1016/j.jtherbio.2020.102638
language
English
LU publication?
yes
id
dccbee89-50d3-40c5-8070-7f0148c53a6c
date added to LUP
2020-07-13 12:32:38
date last changed
2021-03-22 17:39:58
@article{dccbee89-50d3-40c5-8070-7f0148c53a6c,
  abstract     = {Marine endotherms in the polar regions face a formidable thermal challenge when swimming in cold water. Hence, they use morphological (fat, blubber) adjustment and peripheral vasoconstriction to reduce demands for heat production in water. The animals then regain normothermia when resting ashore. In the king penguin (Aptenodytes patagonicus) metabolic rate is lower in fed than in fasted individuals during subsequent rewarming on land. This has been suggested to be a consequence of diversion of blood flow to the splanchnic region in fed birds, which reduces peripheral temperatures. However, peripheral temperatures during recovery have never been investigated in birds with different nutritional status. The aim of this study was, therefore, to measure subcutaneous and abdominal temperatures during the rewarming phase on land in fasted and fed king penguins, and investigate to which extent any different rewarming were reflected in recovery metabolic rate (MRR) after long term immersion in cold water. We hypothesized that fed individuals would have a slower increase of subcutaneous temperatures compared to fasted penguins, and a correspondingly lower MRR. Subcutaneous tissues reached normothermia after 24.15 (back) and 21.36 min (flank), which was twice as fast as in the abdomen (46.82 min). However, recovery time was not affected by nutritional condition. MRR during global rewarming (4.56 ± 0.42 W kg−1) was twice as high as resting metabolic rate (RMR; 2.16 ± 0.59 W kg−1). However, MRR was not dependent on feeding status and was significantly elevated above RMR only until subcutaneous temperature had recovered. Contrary to our prediction, fed individuals did not reduce the subcutaneous circulation compared to fasted penguins and did not show any changes in MRR during subsequent recovery. It seems likely that lower metabolic rate in fed king penguins on land reported in other studies might not have been caused primarily by increased circulation to the visceral organs.},
  author       = {Lewden, Agnès and Bonnet, Batshéva and Nord, Andreas},
  issn         = {0306-4565},
  language     = {eng},
  publisher    = {Elsevier},
  series       = {Journal of Thermal Biology},
  title        = {The metabolic cost of subcutaneous and abdominal rewarming in king penguins after long-term immersion in cold water},
  url          = {http://dx.doi.org/10.1016/j.jtherbio.2020.102638},
  doi          = {10.1016/j.jtherbio.2020.102638},
  volume       = {91},
  year         = {2020},
}