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LEWDEN Agnès

Dernière mise à jour jeudi 28 mai 2015, par Mathilde TISSIER

LEWDEN Agnès

Institut Pluridisciplinaire Hubert Curien - IPHC
Département Ecologie, Physiologie et Ethologie - DEPE
Ecophysiologie et changements environnementaux

Centre National de la Recherche Scientifique - CNRS
UMR 7178 CNRS/Université De Strasbourg - UDS

23 rue Becquerel, 67087 Strasbourg cedex 2, France

Contact : Agnès Lewden


Titre de la thèse : Thermoregulation and body-reserve restoration : study of the energetic and eco-physiological constraints at-sea foraging king penguin (Aptenodytes patagonicus).

Période : 2014-2017

Encadrant : Yves Handrich


Abstract

English

Sea birds species are involved in energetic challenge when they spend time in water. Indeed, water thermal conductivity, 24 times higher than air (Holmer and Berg 1974 ; Kooyman et al. 1976), combined with reduced plumage insulation at depth (Dumonteil et al 1994 ; Stahel and Nicol 1976), results to increase peripheral heat lost and then thermogenic cost. This cost is particularly high to non-flying, diving seabirds such penguins. Thus, energy expenditure (EE) in water at resting represents 1.2 to 2.2 times EE ashore in differents species of penguin (adapted to Enstipp and al. 2005). Furthermore, the energetic challenge is particularly present for these species which have south area distribution, with high latitude characterized by cold water. However, thermogenesis cost is sometimes overestimated if it isn’t considered with thermoregulation processes like the heat substitution produced by digestive and muscle activities (Kaseloo and Lovvorn 2005 ; 2006) or heterothermia (Handrich et al. 1997).
Without considered the travel cost to reach favourable feeding areas (near the oceanic fronts), a day at sea for the King penguin (Aptenodytes patagonicus) is divided into an active phase of deep diving and hunting during daylight and an inactive phase of surfacing and resting during the night. There are some contrasting thermoregulation processes occurring at these two contrasting phases. During daylight, a general hypothermia occurs and is believed to reduce energy expenditure and apnoea capacity (Handrich et al. 1997). The drop of temperature concerns the abdomen, pectoral muscles and the overall skin (Handrich et al. 1997 ; Schmidt et al. 2006). At sunset occurs a re-warming of the deep tissues to normothermia (38-39°C). Surprisingly, even the skin is rewarmed to 38°C, contributing to increase heat-loss during all the night, in water at 5°C. As a result, there is no difference in energy expenditure between nights of inactivity at sea and days of extensive diving.
We hypothesize an energetic conflict between thermoregulation and digestive processes/body reserves restoration at sea (Froget et al. 2004 ; Fahlman et al. 2005 ; Schmidt et al. 2006). During daylight, the organism may be unable to incorporate the end product of prey digestion (free fatty acids, FFA) inside the peripheral subcutaneous adipose tissues (SAT), because skin is not sufficiently blood perfused. During the night, re-warming and re-connecting to blood circulation peripheral tissues is inevitable to end the assimilation of FFA inside the SAT, but is achieved to the detriment of energy conservation, the resting metabolism being as high as during the active part of daylight (Froget et al. 2004).

The aim of my Ph.D is to test this hypothesis. During two field session, we will equip several king penguins with internal loggers able to measure body temperature at different locations and will placed the individual in a sea-water tank at different nutritional stages. Thus, we will investigate :
- Body temperature variations at different locations (internal loggers – thermal camera)
- Activity/Behaviour/Movement (external accelerometer and video camera)
- Energy expenditure (Heart rate and Respirometry)
- Nutritional stage (subcutaneous fat biopsy, blood metabolites and hormones)

Publications / Communications

Publications

Delord K., Pinet P., Pinaud P., De Grissac S., Lewden A., Cherel Y., Weimerskirch H. (2015) Contrasted foraging strategies of Antarctic fulmarine petrels during the breeding and interbreeding periods – In prep
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Cortés PA., Petit M., Lewden A., Milbergue M., Vézina F. (2015) Individual inconsistencies in basal and summit metabolic rate highlight flexibility of metabolic performance in a wintering passerine. J. Exp. Zool. 9999 : 1-12
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Petit M., Lewden A., Vézina F. (2014) How does flexibility in body composition relate to seasonal changes in metabolic performance in a small passerine wintering at northern latitude ? Physiol Biochem Zool. 87(4) : 539-49
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Lewden A., Petit M., Milbergue M., Orio S., Vézina F. (2014) Evidences for use of facultative hypothermia during the day as a mean of energy saving in a small passerine wintering at northern latitudes. Ibis 156 : 321-329
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Petit M., Lewden A., Vézina F. (2013) Intra-Seasonal Flexibility in Avian Metabolic Performance Highlights the Uncoupling of Basal Metabolic Rate and Thermogenic Capacity. PLoS ONE 8(6) : e68292
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Lacoste-Garanger N., Lanshere J., Lewden A. (2013) Assembling of an Emperor Penguin (Aptenodytes forsteri) skeleton in Adelie Land (Antarctica) : interest of Amphipods in the bones cleaning. Cahier d’Anatomie Comparée 5 : 1-17
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Lewden A., Petit M., Vézina F. (2012) Dominant Black-Capped Chickadees pay no maintenance energy costs for their wintering status and are not better at enduring cold than subordinate individuals. J. Com. Physiol. B. 182 : 381-392

Communications

Lewden A., Bost C. and Handrich Y. An over-cost of being a pelagic bird : A possible energetic conflict between thermoregulation and digestive processes. Bio-logging Symposium 5 (BLS5), 22-26 September 2014, Strasbourg, France. Poster.
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Lewden A., Petit M. and Vézina F. (2012) Daytime use of hypothermia is not related to metabolic performance in wintering Black-capped chickadees. Society for Integrative and Comparative Biology (SICB), Charleston, USA.
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Lewden A. and Vézina F. (2011) How does social dominance influence seasonal acclimatization and winter metabolic performance in black-capped chickadees ? Society for Integrative and Comparative Biology (SICB), Salt Lake City, USA.
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Lewden A. and Vézina F. (2011) Socially dominant black-capped chickadees are larger and fatter than subordinates but do not show better metabolic performance in winter ? Societé canadienne ornithilogique/ Ornithologist Society canadien (SCO/OSC), Moncton, Canada. Award for top student presentation.
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Lewden A. and Vézina F. (2011) L’acclimatation au froid est-elle influencée par le rang de dominance chez la mésange à tête noire (Poecile atricapillus) ? Société Québécoise pour l’Etude Biologique du Comportement (SQEBC), Trois Rivière, Canada.