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LEWDEN Agnès

Dernière mise à jour vendredi 2 décembre 2016, 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 in foraging king penguin (Aptenodytes patagonicus).

Période : 2014-2017

Encadrant(s) : Yves Handrich

I did my Masters at the University of Rimouski (Québec, Canada) in 2009, supervised by Prof. François Vézina. I studied the cold acclimatization in Black-capped chickadees ((Poecile atricapillus)) in free-living condition. I developed a special interest for the challenging effects of cold season on birds. Therefore, I have worked for the Chizé centre for biological studies (CEBC-CNRS) as an ornithologist for 15 months in the French scientific station "Dumont d’Urville" in Terre Adelie (Antarctic). I was in charge of data collection on demography and reproduction (e.g animal catching, banding, blood sampling, biometry and growth measurements, colony census) of 9 species (8 marine birds and 1 marine mammal) in archipelagos. I undertook my Ph.D project in 2014 under a three-year doctoral fellowship funded by the French ministry of education and Research.

My research interests are focused on thermoregulation in thermal challenging context, and the impact of body temperature variations in energy budget and heat transfer between organisms and their environment.

Abstract

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 favorable 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, where abdominal temperatures measured in free living individuals fell as low as 11 °C during foraging (Handrich et al., 1997), and this has led to the suggestion of a regional hypothermia as a mechanism to lower diving metabolism and increase breath-hold duration (Butler, 2004). The most remarkable body temperature adjustments were observed in KPs.
At sunset, when the bird returns to the sea surface after the end of diving day, body temperature increases in deep and peripheral tissues to ultimately bring the bird back to normothermia (i.e 37°C) (Fahlman et al. 2005 ; Schmidt et al. 2006). Surprisingly, even the skin is rewarmed to 37°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 resting nights at sea surface and days of extensive diving (Froget et al. 2004).

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, rewarming 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 that maintained peripheral perfusion during inactivity at night is required to allow fat deposition, and this might explain the observed general rewarming that occurs after foraging, when birds rest at the surface, we have equipped several king penguins with internal loggers able to measure body temperature at different locations and placed individuals in a shallow sea-water tank at different nutritional stages (picture 1 below, portfolio).

With this experimental setup we are investigating 1) king penguins regional heterothermy. We are describing temperature variations in each tissue (peripheral and internal) in function of nutritional condition (feed or fast) in several individuals.

Furthermore, we will investigate 2) the tissue temperature variations during transitional period from getting out of cold sea water and staying on land (with ambient temperatures closed to thermoneutrality). To measure these variations, we use individuals equipped with internal loggers in captive condition and non-invasive infrared thermography (e.g Tattersall et al. 2009 ; Jerem et al. 2015 ; Van de Ven et al. 2016) to study the occurrence and thermal consequences of peripheral vasodilation (picture 2 below, portfolio).

Finally, we will use the previous setup and a respirometry chain to measure the oxygen consumption (picture 3 below, portfolio) to understand the rewarming energy cost occurring in free-living conditions during inactive phase in foraging trip.

Publications

Lewden A., Picard B., Tessa van Valsum Enstipp M. and Handrich Y. (2016) Why do king penguins maintain expensive peripheral normothermia when resting in sea water ? (In prep).

Lewden A., Enstipp M., Picard B. and Handrich Y. (2016) An over-cost to maintain normothermia in cold water in fasting condition. (In prep).

Lewden A., Nord A., Petit M. and Vézina F. (2016) Body temperature responses to handling stress in wintering Black-capped Chickadees ( (Poecile atricapillus L.). (Submitted).

Delord K., Pinet P., Pinaud P., De Grissac S., Lewden A., Cherel Y., Weimerskirch H. (2016). Contrasted foraging strategies of Antarctic fulmarine petrels during the breeding and interbreeding periods. Ibis 158 : 569-586

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

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

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

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

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

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 (First author)

Lewden A., Manfred E. and Y. Handrich 2016. King penguin thermoregulation in water : To understand the paradox 2016. University of Pretoria.

Lewden A., Manfred E., van Walsum T., Bonnet B., Picard B and Y. Handrich 2016. On being a pelagic bird : Conflicting demands of thermoregulation and digestive processes at sea. International penguin congress 9th (ICP9) (Oral)

Lewden A., Manfred E., van Walsum T., Bonnet B., Picard B and Y. Handrich 2016, On being a pelagic bird : Conflicting demands of thermoregulation and digestive processes at sea. “Society of experimental biology” (SEB) (Oral)

Lewden A., Picard B., van Walsum T., Bost C., Hestin T. and Y. Handrich 2015. King penguins rewarm their skin temperature to normothermia during the night at sea : a descriptive study in condition of captivity “International Congress of Comparative Physiology and Biochemistry” (ICCPB) (Poster)

Lewden A., Bost C. and Y. Handrich 2014 ; An over-cost of being a pelagic bird : A possible energetic conflict between thermoregulation and digestive processes. “Bio-logging 5” (BLS) (Poster)

Lewden A., Petit M. and F. Vézina 2012- Daytime use of hypothermia is not related to metabolic performance in wintering Black-Capped Chickadees. “Society for Integrative and Comparative Biology” (SICB) (Poster)

Lewden A., and F. Vézina 2011 How does social dominance influence seasonal acclimatization and winter metabolic performance in Black-Capped Chickadees ? “Society for Integrative and Comparative Biology” (SICB) (Oral)

Lewden A. and F. Vézina 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) (Oral) Award for the top oral presentation

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) (Oral)

Teaching

For Bachelor Students :

2014/2015 and 2015/2016 Course on : animal biodiversity. Faculty of biology, University of Strasbourg.
2014/2015 and 2015/2016 Course on : comparative anatomy of metazoans. Faculty of biology, University of Strasbourg.

Portfolio