Antoine Grisart, Mathieu Casado, Vasileios Gkinis, Bo Vinther, Philippe Naveau, Mathieu Vrac, Thomas Laepple, Bénédicte Minster, Fréderic Prié, Barbara Stenni, Elise Fourré, Hans-Christian Steen Larsen, Jean Jouzel, Martin Werner, Katy Pol, Valérie Masson-Delmotte, Maria Hoerhold, Trevor Popp, Amaelle Landais. (2022). Sub-millennial climate variability from high resolution water isotopes in the EDC ice core.
Abstract: The EPICA Dome C (EDC) ice core provides the longest continuous climatic record covering the last 800 000 years (800 kyrs). Obtaining homogeneous high resolution measurements and accounting for diffusion provide a unique opportunity to study the evolution of decadal to millennial variability within the past glacial and interglacial periods. We present here a compilation of high resolution (11 cm) water isotopic records with 27 000 δ18O measurements and 7 920 δD measurements (covering respectively 94 % and 27 % of the whole EDC record), including published and new measurements (2 900 for both δ18O and δD) over the last 800 kyrs on the EDC ice core. We show that overlapping measurement series performed over multiple depth ranges over the past 20 years, using different analytical methods and in different laboratories, are consistent within analytical uncertainty, and therefore can be combined to provide a homogeneous data set. A frequency decomposition of the most complete δ18O record and a simple assessment of the possible influence of diffusion on the measured profile shows that the variability during glacial periods at multi-decadal to multi-centennial timescale is higher than variability of the interglacial periods. This analysis shows as well that during interglacial periods characterized by a temperature optimum at its beginning, the multi-centennial variability is the strongest over this temperature optimum.
Programme: 1110
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Antoine Martin, Marie-Noëlle Houssais, Hervé Le Goff, Claudie Marec, Denis Dausse. (2017). Circulation and water mass transports on the East Antarctic shelf in the Mertz Glacier region (Vol. 126).
Abstract: The East Antarctic shelf off Adélie-George V Land is known to be an important region for Dense Shelf Water (DSW) formation as a result of intense sea ice production in the Mertz Glacier Polynya during the winter season. It is also a region where the warm modified Circumpolar Deep Water (mCDW) penetrates onto the shelf during the summer. Using hydrographic observations from a summer survey in 2008 we implement a box inverse model to propose a comprehensive view of the steady state circulation on this shelf in summer. Additional information from mooring observations collected on the depression slope is used to provide context to the retrieved circulation scheme. Over the depression slope, the summer baroclinic structure of the currents is found to contrast with the almost barotropic structure in winter. The summer circulation is strongly constrained by the DSW distribution and forms a clockwise circulation primarily transporting the fresh surface waters and the warm mCDW around the dome of DSW. Over the upper flank of the Mertz Bank, the inflow branch transports the mCDW towards the Mertz Glacier, while, over the lower part of the slope, the outflow branch returns to the sill a diluted mode of the same water mass. A total of 0.19Sv of mCDW inflows at the sill and two-third reach the Mertz Glacier and recirculate in front of it, allowing the mCDW to penetrate into the deeper part of the depression. Possible scenarios of interaction between the mCDW and the DSW with the glacier are examined. It is shown that, despite the water mass pathways and transports suggest possible ice-ocean interaction, both lateral and basal melting were likely small in summer 2008. Finally, our results suggest that, in addition to bathymetric features, the distribution of the residual DSW which is left from the preceding winter sets up regional pressure gradients which provide a seasonal control on the shelf circulation. In particular, the spring collapse of the convective patch would contribute to setting up a deep pycnocline which strongly impacts the shelf circulation in the following summer, with possible feedback of the mCDW transports on the polynya activity and water mass formation.
Keywords: Adélie Georges V Land Antarctica Continental shelf Freshwater transport Heat transport Modified Circumpolar Deep Water
Programme: 452
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Antoine Rocaboy. (2022). Soil microbial biomass and nutrient concentrations under the effect of vegetation cover, biological invasion and habitats of the Kerguelen Islands..
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Antoine Stier, Quentin Schull, Pierre Bize, Emilie Lefol, Mark Haussmann, Damien Roussel, Jean-Patrice Robin, Vincent A. Viblanc. (2019). Oxidative stress and mitochondrial responses to stress exposure suggest that king penguins are naturally equipped to resist stress (Vol. 9).
Abstract: Exposure to unpredictable environmental stressors could influence animal health and fitness by inducing oxidative stress, potentially through downstream effects of glucocorticoid stress hormones (e.g. corticosterone) on mitochondrial function. Yet, it remains unclear whether species that have evolved in stochastic and challenging environments may present adaptations to alleviate the effects of stress exposure on oxidative stress. We tested this hypothesis in wild king penguins by investigating mitochondrial and oxidative stress responses to acute restraint-stress, and their relationships with baseline (potentially mirroring exposure to chronic stress) and stress-induced increase in corticosterone levels. Acute restraint-stress did not significantly influence mitochondrial function. However, acute restraint-stress led to a significant increase in endogenous antioxidant defences, while oxidative damage levels were mostly not affected or even decreased. High baseline corticosterone levels were associated with an up-regulation of the glutathione antioxidant system and a decrease in mitochondrial efficiency. Both processes might contribute to prevent oxidative damage, potentially explaining the negative relationship observed between baseline corticosterone and plasma oxidative damage to proteins. While stress exposure can represent an oxidative challenge for animals, protective mechanisms like up-regulating antioxidant defences and decreasing mitochondrial efficiency seem to occur in king penguins, allowing them to cope with their stochastic and challenging environment.
Programme: 119
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Antoine, A. (2022). Beneath the Antarctic sea-ice: Fine-scale analysis of Weddell seal (Leptonychotes weddellii, Lesson 1826) behaviour and predator prey interactions, using micro-sonar data and video recordings in Terre Adélie.
Abstract: The sea-ice zone constitutes the breeding and foraging habitat of large populations of ice-based species, pointing at its far-reaching ecological importance. Given its sensitivity to global warming, there is an urgent need for determining how predators use their environment, to understand and predict their response to climate variability. New perspectives are offered by miniature animal-borne sensors: in 2019, 3 sonar tags were deployed on lactating female Weddell seals for 7 days in Terre Adélie to study 3D animal movement and fine-scale predator-prey interactions. Lactating females demonstrated central-place foraging strategy, with restricted foraging area (3-6 km) and mostly benthic dives (97% of dives, visualising the seafloor on echograms). Their foraging effort was constrained by the presence of their pup: females spent most of their time hauling out (77% of overall recordings). The time spent underwater was mostly dedicated to diving (>5m) (1.36 on 7days, 854 dives recorded), as opposed to shallower under ice activities (<5m) (0.3 days). A total of 331 prey capture attempts (PrCA) were recorded, using tri-axial acceleration data, of which 125 prey (4.7 ± 1.5 cm on average) were identified by the sonar on 78 dives (4.24 ± 3.99 PrCA/dive). All PCA occur on the seafloor, at shallower depth than usual Weddell seal records (88 ± 30 m). Lactation is therefore a period of physiological stress, with foraging limited by pup compared with other parts of the life cycle. Using functional principal component analysis and model-based clustering on high resolution dive data, we found that PrCAs occur mostly in 2 of the 5 dive shape clusters. Foraging dives are characterised by W or V shape and high sinuosity, at the scale of the dive (W shapes) or during the ascent phase (V shapes). During the approach phase, seals constantly scan the area by regularly moving their head left to right, suggesting opportunistic behaviour. Shallow phase behaviour was studied using video recordings (2h recorded per seal). Seals spent most of their time interacting with their pup (33%) and hauling-out (42%). Most mother-pup interactions were on sea-ice (71%), as opposed to underwater (29%). The results suggest lactating females’ energy budget changes, with lactation being a period of physiological stress. This period of feeding pressure might put them at higher risk regarding adaptation to environmental variability.
Programme: 1182
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Antomarchi V. (2010). La création du parc National des Pingualuit au Nunavik (Nord Québec), une promotion touristique révélatrice de divergences d’opinions. Bachelor's thesis, , .
Abstract: in Laslaz L., Gauchon C., Duval-Massaloux M. et Héritier S., coord. (2010), Espaces protégés, acceptation sociale et conflits environnementaux, Cahiers de Géographie, n°10, collection EDYTEM, pp. 101-112
Programme: 1043
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Antomarchi V. (2011). “Images touristiques du Grand Nord : rêves et clichés”
. Bachelor's thesis, , .
Abstract: Actes du Colloque international des Dialogues européens d’Evian, Réchauffement global, changement climatique, sociétés et cultures de Russie et d’Europe, en russe éditions du Baïkal, en français, Le Vieil Annecy, 2011.
Programme: 1043
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ANTOMARCHI V. (2009). Les images touristiques du Grand Nord dans les brochures des TO français, Université de Poitiers, 14 juin.
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ANTOMARCHI V. (2011). La perception de l'environnement au Nunavik : approches autochtones et occidentales, in Colloque international 'Indigenous people and environment', Université de Bordeaux, 8-10 décembre.
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ANTOMARCHI V. (2012). « Imaginer l’autre : la rencontre avec les Inuit de l’Arctique canadien (1906-1936) à travers le regard de Thierry Mallet et de Robert Flaherty pour la société française Revillon Frères », Mobilités, territoires et imaginaires, in Dornel L., Guicharnaud-Tollis M., Parson M., Payo J.Y. (dir), in Presses Universitaires de Bordeaux.
Abstract: Actes du colloque international TEMA 2 « Mobilités, territoires et imaginaires en Amérique des indépendances jusqu’aux années 1930 », Université de Pau
Programme: 1043
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