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Stratégies de thermorégulation liées aux contraintes physiologiques et environnementales chez le manchot royal (Aptenodytes patagonicus)

Abstract : The energetic cost of foraging activities in King Penguin (Aptenodytes patagonicus) consists to reach favourable areas, realizes depth diving to attempt fish patch and resting in high latitude cold water. Several studies have shown that resting in cold water could be represent a more expensive cost than realized depth diving. Indeed, this paradox is probably linked with contrasting thermoregulation processes. During daylight, a general hypothermia occurs and is believed to reduce energy expenditure. At sunrise occurs a re-warming to normothermia, contributing to increase heat-loss during the night. We hypothesise an energetic conflict between thermoregulation and digestive processes. During daylight, the organism may be unable to assimilate the end product of prey digestion (free fatty acids) inside the peripheral subcutaneous adipose tissues (SAT), because skin is no more blood perfused. During the night, re-warming and re-connecting to blood circulation peripheral tissues could be inevitable to end the assimilation of FFA inside the SAT. In a first step, we have reproduced the conditions of a resting night at sea and events of rewarming skin temperature, using a sea water tank in which king penguins equipped with internal temperature loggers were maintained several days. In a second step, we have tested a generalisation of our hypothesis studying body temperature variations on penguins fast and feed. Finally, we have measured the cost to maintain normothermia in cold water with respirometry measures and investigated peripheral vasodilation with body temperature variations and infrared thermography.
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Submitted on : Wednesday, April 18, 2018 - 4:19:10 PM
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Agnès Lewden. Stratégies de thermorégulation liées aux contraintes physiologiques et environnementales chez le manchot royal (Aptenodytes patagonicus). Bioclimatologie. Université de Strasbourg, 2017. Français. ⟨NNT : 2017STRAJ125⟩. ⟨tel-01770157⟩

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