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Goutte Aurélie, Cherel Yves, Houssais Marie-Noëlle, Klein Vincent, Ozouf-Costaz Catherine, Raccurt Mireille, Robineau Camille, Massé Guillaume, . (2013). Diatom-Specific Highly Branched Isoprenoids as Biomarkers in Antarctic Consumers . PLOS ONE, 8(2), e56504.
Abstract: The structure, functioning and dynamics of polar marine ecosystems are strongly influenced by the extent of sea ice. Ice algae and pelagic phytoplankton represent the primary sources of nutrition for higher trophic-level organisms in seasonally ice-covered areas, but their relative contributions to polar marine consumers remain largely unexplored. Here, we investigated the potential of diatom-specific lipid markers and highly branched isoprenoids (HBIs) for estimating the importance of these two carbon pools in an Antarctic pelagic ecosystem. Using GC-MS analysis, we studied HBI biomarkers in key marine species over three years in Adélie Land, Antarctica: euphausiids (ice krill Euphausia crystallorophias and Antarctic krill E. superba), fish (bald notothens Pagothenia borchgrevinki and Antarctic silverfish Pleuragramma antarcticum) and seabirds (Adélie penguins Pygoscelis adeliae, snow petrels Pagodroma nivea and cape petrels Daption capense). This study provides the first evidence of the incorporation of HBI lipids in Antarctic pelagic consumers. Specifically, a di-unsaturated HBI (diene) of sea ice origin was more abundant in ice-associated species than in pelagic species, whereas a tri-unsaturated HBI (triene) of phytoplanktonic origin was more abundant in pelagic species than in ice-associated species. Moreover, the relative abundances of diene and triene in seabird tissues and eggs were higher during a year of good sea ice conditions than in a year of poor ice conditions. In turn, the higher contribution of ice algal derived organic matter to the diet of seabirds was related to earlier breeding and higher breeding success. HBI biomarkers are a promising tool for estimating the contribution of organic matter derived from ice algae in pelagic consumers from Antarctica.
Programme: 109,131,1024
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Grémillet David, Prudor Aurélien, le Maho Yvon, Weimerskirch Henri, . (2012). Vultures of the Seas: Hyperacidic Stomachs in Wandering Albatrosses as an Adaptation to Dispersed Food Resources, including Fishery Wastes
. PLoS ONE, 7(6), e37834–.
Abstract: Animals are primarily limited by their capacity to acquire food, yet digestive performance also conditions energy acquisition, and ultimately fitness. Optimal foraging theory predicts that organisms feeding on patchy resources should maximize their food loads within each patch, and should digest these loads quickly to minimize travelling costs between food patches. We tested the prediction of high digestive performance in wandering albatrosses, which can ingest prey of up to 3 kg, and feed on highly dispersed food resources across the southern ocean. GPS-tracking of 40 wandering albatrosses from the Crozet archipelago during the incubation phase confirmed foraging movements of between 4754705 km, which give birds access to a variety of prey, including fishery wastes. Moreover, using miniaturized, autonomous data recorders placed in the stomach of three birds, we performed the first-ever measurements of gastric pH and temperature in procellariformes. These revealed surprisingly low pH levels (average 1.50±0.13), markedly lower than in other seabirds, and comparable to those of vultures feeding on carrion. Such low stomach pH gives wandering albatrosses a strategic advantage since it allows them a rapid chemical breakdown of ingested food and therefore a rapid digestion. This is useful for feeding on patchy, natural prey, but also on fishery wastes, which might be an important additional food resource for wandering albatrosses.
Programme: 109
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Quéguiner, Bernard &Amp; Obernosterer, Ingrid &Amp; Blain, Stéphane &Amp; Christaki, Urania &Amp; Leblanc, Karine &Amp; Cotte, Cedric &Amp; Delegrange, Alice &Amp; Cherel, Yves &Amp; Guinet, Christophe &Amp; Zhou, Meng &Amp; Hunt, Brian &Amp; Pakhomov, Evgeny &Amp; Planchon, Frederic. (2019). Pelagic ecosystem functioning in the vicinity of the Kerguelen Islands (Southern Ocean): Towards an end-to-end approach. Bachelor's thesis, , .
Abstract: Results acquired over more than two decades now make it possible to outline the functioning of the pelagic ecosystem off the Kerguelen Islands. Although the structuring role of natural iron fertilization has been demonstrated both in terms of productivity and the structuring of pelagic communities, recent results raise questions about the paradigm of the coupling between carbon and silicon biogeochemical cycles in naturally iron-fertilized environments of the Southern Ocean. Similarly, new, recently published results highlight the role of biological processes, e.g. the partitioning of grazing between micro- and mesozooplankton, or the life cycles of primary producers (including senescence and resting spore formation) in the operation of the biological carbon pump. At the same time, several conceptual models have been developed to better describe the functioning of pelagic ecosystems with regards to the limiting nutritional factors of the first trophic levels. The synthesis of current data lays the foundation for the current functioning of the pelagic ecosystems surrounding the Kerguelen Archipelago while new ongoing and future studies, especially under the framework of the MOBYDICK Project, aim at achieving an in-depth understanding of the processes linking biogeochemistry and biodiversity in an end–to–end approach, i.e., from prokaryotes to apex predators.
Programme: 1201
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Manfred R. Enstipp, Charles-André Bost, Céline Le Bohec, Nicolas Chatelain, Henri Weimerskirch, Yves Handrich. (2021). The early life of king penguins: ontogeny of dive capacity and foraging behaviour in an expert diver (Vol. 224). Bachelor's thesis, , .
Abstract: The period of emancipation in seabirds, when juveniles change from a terrestrial existence to a life at sea, is associated with many challenges. Apart from finding favourable foraging sites, they have to develop effective prey search patterns and physiological capacities that enable them to capture sufficient prey to meet their energetic needs. Animals that dive to forage, such as king penguins (Aptenodytes patagonicus), need to acquire an adequate breath-hold capacity, allowing them to locate and capture prey at depth. To investigate the ontogeny of their dive capacity and foraging performance, we implanted juvenile king penguins before their first departure to sea and also adult breeders with a data-logger recording pressure and temperature. We found that juvenile king penguins possess a remarkable dive capacity when leaving their natal colony, enabling them to conduct dives in excess of 100 m within their first week at sea. Despite this, juvenile dive/foraging performance, investigated in relation to dive depth, remained below the adult level throughout their first year at sea, probably reflecting physiological limitations as a result of incomplete maturation. A significantly shallower foraging depth of juveniles, particularly during their first 5 months at sea, could also indicate differences in foraging strategy and targeted prey. The initially greater wiggle rate suggests that juveniles fed opportunistically and also targeted different prey from adults and/or that many of the wiggles of juveniles reflect unsuccessful prey-capture attempts, indicating a lower foraging proficiency. After 5 months, this difference disappeared, suggesting sufficient physical maturation and improvement of juvenile foraging skills.
Keywords: Animals Behavior, Animal Bio-logging Diving Feeding Behavior Foraging proficiency Ontogeny Seabirds Spheniscidae Temperature Wiggles
Programme: 137,394
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Manfred R. Enstipp, Charles-André Bost, Céline Le Bohec, Caroline Bost, Robin Laesser, Yvon Le Maho, Henri Weimerskirch, Yves Handrich. (2019). The dive performance of immature king penguins following their annual molt suggests physiological constraints (Vol. 222). Bachelor's thesis, , .
Abstract: Skip to Next Section Like all birds, penguins undergo periodic molt, during which they replace old feathers. However, unlike other birds, penguins replace their entire plumage within a short period while fasting ashore. During molt, king penguins (Aptenodytes patagonicus) lose half of their initial body mass, most importantly their insulating subcutaneous fat and half of their pectoral muscle mass. The latter might challenge their capacity to generate and sustain a sufficient mechanical power output to swim to distant food sources and propel themselves to great depth for successful prey capture. To investigate the effects of the annual molt fast on their dive/foraging performance, we studied various dive/foraging parameters and peripheral temperature patterns in immature king penguins across two molt cycles, after birds had spent their first and second year at sea, using implanted data-loggers. We found that the dive/foraging performance of immature king penguins was significantly reduced during post-molt foraging trips. Dive and bottom duration for a given depth were shorter during post-molt and post-dive surface interval duration was longer, reducing overall dive efficiency and underwater foraging time. We attribute this decline to the severe physiological changes that birds undergo during their annual molt. Peripheral temperature patterns differed greatly between pre- and post-molt trips, indicating the loss of the insulating subcutaneous fat layer during molt. Peripheral perfusion, as inferred from peripheral temperature, was restricted to short periods at night during pre-molt but occurred throughout extended periods during post-molt, reflecting the need to rapidly deposit an insulating fat layer during the latter period.
Programme: 109,137,394
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Manfred R. Enstipp, Charles-André Bost, Céline Le Bohec, Caroline Bost, Yvon Le Maho, Henri Weimerskirch, Yves Handrich. (2017). Apparent changes in body insulation of juvenile king penguins suggest an energetic challenge during their early life at sea (Vol. 220). Bachelor's thesis, , .
Abstract: Skip to Next Section Little is known about the early life at sea of marine top predators, like deep-diving king penguins (Aptenodytes patagonicus), although this dispersal phase is probably a critical phase in their life. Apart from finding favourable foraging sites, they have to develop effective prey search patterns as well as physiological capacities that enable them to capture sufficient prey to meet their energetic needs. To investigate the ontogeny of their thermoregulatory responses at sea, we implanted 30 juvenile king penguins and 8 adult breeders with a small data logger that recorded pressure and subcutaneous temperature continuously for up to 2.5 years. We found important changes in the development of peripheral temperature patterns of foraging juvenile king penguins throughout their first year at sea. Peripheral temperature during foraging bouts fell to increasingly lower levels during the first 6 months at sea, after which it stabilized. Most importantly, these changes re-occurred during their second year at sea, after birds had fasted for ∼4 weeks on land during their second moult. Furthermore, similar peripheral temperature patterns were also present in adult birds during foraging trips throughout their breeding cycle. We suggest that rather than being a simple consequence of concurrent changes in dive effort or an indication of a physiological maturation process, these seasonal temperature changes mainly reflect differences in thermal insulation. Heat loss estimates for juveniles at sea were initially high but declined to approximately half after ∼6 months at sea, suggesting that juvenile king penguins face a strong energetic challenge during their early oceanic existence.
Programme: 109,137,394
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Nesterova Anna P, Chiffard Jules, Couchoux Charline, Bonadonna Francesco, . (2013). The invisible cues that guide king penguin chicks home. The use of magnetic and acoustic cues during orientation and short-range navigation
. J. Exp. Biol., 216, 1491–1500.
Abstract: King penguins (Aptenodytes patagonicus) live in large and densely populated colonies, where navigation can be challenging due to the presence of many conspecifics that could obstruct locally available cues. Our previous experiments demonstrated that visual cues were important but not essential for king penguin chicks' homing. The main objective of this study was to investigate the importance of non-visual cues, such as magnetic and acoustic cues, for chicks' orientation and short-range navigation. In a series of experiments, the chicks were individually displaced from the colony to an experimental arena where they were released under different conditions. In the magnetic experiments, a strong magnet was attached to the chicks' heads. Trials were conducted in daylight and at night to test the relative importance of visual and magnetic cues. Our results showed that when the geomagnetic field around chicks was modified, their orientation in the arena and the overall ability to home was not affected. In the low sound experiment we limited the acoustic cues available to the chicks by putting ear pads over their ears, and in the loud sound experiment we provided additional acoustic cues by broadcasting colony sounds on the opposite side of the arena to the real colony. In the low sound experiment, the behavior of the chicks was not affected by the limited sound input. In the loud sound experiment, the chicks reacted strongly to the colony sound. These results suggest that king penguin chicks may use the sound of the colony while orienting towards their home.
Programme: 354
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Goutte Aurélie, Clément-Chastel Céline, Moe Børge, Bech Claus, Gabrielsen Geir Wing, Chastel Olivier, . (2011). Experimentally reduced corticosterone release promotes early breeding in black-legged kittiwakes
. The Journal of Experimental Biology, 214(12), 2005–2013.
Abstract: Breeding at the right time is important for successful reproduction. In birds, stressful environmental conditions are known to delay the timing of breeding but the underlying mechanisms are poorly understood. The stress hormone corticosterone appears to be a good candidate for mediating egg-laying date according to early environmental conditions and physiological state. By experimentally reducing the release of corticosterone in black-legged kittiwakes during the pre-laying period, we tested whether egg-laying date was mechanistically linked to corticosterone levels. Male and female kittiwakes were implanted with a low dose of exogenous corticosterone to inhibit endogenous corticosterone production. According to our predictions, the experimental reduction of corticosterone release was paralleled by a significant advancement of egg laying in females (around 4 days earlier). In addition, females with experimentally reduced corticosterone release gained mass during the pre-laying period compared with controls. Ultimately, the advancement of egg laying in females with experimentally reduced corticosterone levels was associated with an enhanced breeding success. This effect was strongly sex specific. In corticosterone-treated male kittiwakes, egg-laying date and reproductive success were not affected, but breeding probability was lower than in controls. This corticosterone treatment did not influence immediate clutch size, or return rate and breeding decision the following year. Our results support the hypothesis that corticosterone secretion during the pre-laying period mediates the timing of breeding in this long-lived seabird, possibly through the dynamics of energy reserves.
Programme: 330
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Groscolas R, Viera V, Guerin N, Handrich Y, Côté S D, . (2010). Heart rate as a predictor of energy expenditure in undisturbed fasting and incubating penguins.
. J. Exp. Biol., 213(1), 153–60.
Abstract: Heart rate (f(H)) measurement offers the possibility to monitor energy expenditure (EE) in wild animals if the EE/f(H) relationship for the species, physiological stages and activities of interest is known. This relationship has been extensively studied using oxygen consumption rate ( ) measurement in captive, repeatedly handled king penguins (Aptenodytes patagonicus). Unfortunately, the potential effects of stress on the observed relationships resulting from handling and confinement were not considered. This study is the first involving undisturbed animals, and determines the EE/f(H) relationship in naturally fasting and freely incubating or captivity-acclimatized male and female king penguins. EE determination was based on (1) the measurement of body mass loss during periods of phase II fasting, and (2) the calculation of its energy equivalent from changes in body composition, i.e. 23.9 kJ g(-1). f(H) levels in freely incubating and captivity-acclimatized birds were found to be 50-70% lower than those previously reported for resting king penguins during measurements. Significant EE/f(H) relationships were found in freely incubating and captive males and females (R(2)=0.59 to 0.84), with no difference observed between genders. The best overall relationship was obtained by including fasting duration (t, days) in the model: EE=818+43.7xf(H)+36.3t-1.4txf(H) (R(2)=0.91). This equation yielded EE estimates approximately 26% higher than the previously reported 'best' predictive equation in king penguins, and even more so when f(H) was low. This result suggests that stress induces a disproportionate increase of f(H) vs O(2) consumption, and that the use of EE/f(H) relationships obtained in stressed birds could lead to underestimated EE values.
Keywords: Animals, Energy Metabolism, Fasting, Fasting: physiology, Female, Heart Rate, Male, Nesting Behavior, Nesting Behavior: physiology, Spheniscidae, Spheniscidae: physiology,
Programme: 119;394
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Angelier Frédéric, Giraudeau Mathieu, Bost Charles-André, Le Bouard Fabrice, Chastel Olivier, . (2009). Are stress hormone levels a good proxy of foraging success? An experiment with king penguins, Aptenodytes patagonicus.
. J. Exp. Biol., 212(17), 2824–9.
Abstract: In seabirds, variations in stress hormone (corticosterone; henceforth CORT) levels have been shown to reflect changing marine conditions and, especially, changes in food availability. However, it remains unclear how CORT levels can be mechanistically affected by these changes at the individual level. Specifically, the influence of food acquisition and foraging success on CORT secretion is poorly understood. In this study, we tested whether food acquisition can reduce baseline CORT levels (;the food intake hypothesis') by experimentally reducing foraging success of King Penguins (Aptenodytes patagonicus). Although CORT levels overall decreased during a foraging trip, CORT levels did not differ between experimental birds and controls. These results demonstrate that mass gain at sea is not involved in changes in baseline CORT levels in this species. The overall decrease in CORT levels during a foraging trip could result from CORT-mediated energy regulation (;the energy utilisation hypothesis'). Along with other evidence, we suggest that the influence of foraging success and food intake on CORT levels is complex and that the ecological meaning of baseline CORT levels can definitely vary between species and ecological contexts. Therefore, further studies are needed to better understand (1) how baseline CORT levels are functionally regulated according to energetic status and energetic demands and (2) to what extent CORT can be used to aid in the conservation of seabird populations.
Keywords: Animals, Body Composition, Corticosterone, Corticosterone: blood, Eating, Feeding Behavior, Female, Male, Spheniscidae, Spheniscidae: anatomy & histology, Spheniscidae: metabolism, Spheniscidae: physiology,
Programme: 109;394
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