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Lucie Bazin. (2015). Analyse de l’air piégé dans les carottes de glace de Dôme C et Talos Dôme pour mieux contraindre le rôle du forçage orbital et des gaz à effet de serre dans les variations glaciaire-interglaciaire.
Abstract: Thèse soutenue le 29 janvier 2015. Université Saint Quentin.
Discipline : météorologie, océanographie physique de l'environnement
Laboratoire : LSCE
Programme: 902
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Bazin L, Landais A, Masson-Delmotte V, Ritz C, Picard G, Capron E, Jouzel J, Dumont M, Leuenberger M, Prié F, . (2015). Phase relationships between orbital forcing and the composition of air trapped in Antarctic ice cores
. Climate of the Past Discussions, 11(2), 1437–1477.
Abstract: Orbital tuning is central for ice core chronologies beyond annual layer counting, available back to 60 ka (i.e. thousand of years before 1950) for Greenland ice cores.
While several complementary orbital tuning tools have recently been developed using delta 18O atm,delta O2/N2, and air content with different orbital targets, quantifying their uncertainties remains a challenge. Indeed, the exact processes linking variations of these parameters, measured in the air trapped in ice, to their orbital targets are not yet fully nderstood. Here, we provide new series of delta O2/N2 and delta 18O atm data encompassing Marine Isotopic Stage (MIS) 5 (between 100–160 ka) and the oldest part(380–800 ka) of the East Antarctic EPICA Dome C (EDC) ice core. For the first time, the measurements over MIS 5 allow an inter-comparison of delta O2/N2 and delta 18O atm records from three East Antarctic ice core sites (EDC, Vostok and Dome F). This comparison highlights a site-specific relationship between delta O2/N2 and its local summer solstice insolation. Such a relationship increases the uncertainty associated with the use of delta O2/N2 as a tool for orbital tuning. Combining records of delta 18O atm and delta O2/N2 from Vostok and EDC, we evidence a loss of orbital signature for these two parameters during periods of minimum eccentricity (~400,~720–800 ka). Our dataset reveals a time-varying lag between delta O2/N2 and delta 18O atm over the last 800 ka that we interpret as variations of the lag between delta 18O atm and precession. Large lags of ~5 ka are identified during Terminations I and II, associated with strong Heinrich events. On the opposite, minimal lags (~1–2 ka) are identified during four periods characterized by high eccentricity, intermediate ice volume and no Heinrich events (MIS 6–7, the end of MIS 9, MIS 15 and MIS 17). We therefore suggest that the occurrence of Heinrich events influences the response of delta 18O atm to precession.
Programme: 902
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Dietz Lars, Arango Claudia P, Dömel Jana S, Halanych Kenneth M, Harder Avril M, Held Christoph, Mahon Andrew R, Mayer Christoph, Melzer Roland R, Rouse Greg W, Weis Andrea, Wilson Nerida G, Leese Florian, . (2015). Regional differentiation and extensive hybridization between mitochondrial clades of the Southern Ocean giant sea spider Colossendeis megalonyx.
. Royal Society open science, 2(7), 140424.
Abstract: Assessing the enormous diversity of Southern Ocean benthic species and their evolutionary histories is a central task in the era of global climate change. Based on mitochondrial markers, it was recently suggested that the circumpolar giant sea spider Colossendeis megalonyx comprises a complex of at least six cryptic species with mostly small and non-overlapping distribution ranges. Here, we expand the sampling to include over 500 mitochondrial COI sequences of specimens from around the Antarctic. Using multiple species delimitation approaches, the number of distinct mitochondrial OTUs increased from six to 15-20 with our larger dataset. In contrast to earlier studies, many of these clades show almost circumpolar distributions. Additionally, analysis of the nuclear internal transcribed spacer region for a subset of these specimens showed incongruence between nuclear and mitochondrial results. These mito-nuclear discordances suggest that several of the divergent mitochondrial lineages can hybridize and should not be interpreted as cryptic species. Our results suggest survival of C. megalonyx during Pleistocene glaciations in multiple refugia, some of them probably located on the Antarctic shelf, and emphasize the importance of multi-gene datasets to detect the presence of cryptic species, rather than their inference based on mitochondrial data alone.
Programme: 1124
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AUVINET J., BELKADI L., BONILLO C., COUTANCEAU J.P., DETTAI Agnès, GUIDI-RONTANI C., GRACA P., HIGUET D. & OZOUF-COSTAZ C. (2015). Accumulation de rétrotransposons et remaniements chromosomiques extensifs au cours de la diversification des Trematominae, téléostéens antarctiques. Poster. VIe Rencontres de l'Ichtyologie en France, Paris, 24-27 mars 2015.
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O. Rey, A. d’Hont, J.-P. Coutanceau, E. Pisano, S. Chilmonczyk and C. Ozouf-Costaz. (2015). Cephalic kidney and spleen cell culture in Antarctic teleosts. In Ozouf-Costaz C., Pisano. E., Foresti F. & L.F. de Almeida toledo, Eds. Fish cytogenetic techniques. Rau-fin fish and chondrichthyans. pp. 74-81.CRC Press..
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Amory C, Trouvilliez A, Gallée H, Favier V, Naaim-Bouvet F, Genthon C, Agosta C, Piard L, Bellot H, . (2015). Comparison between observed and simulated aeolian snow mass fluxes in Adélie Land, East Antarctica
. The Cryosphere, 9(4), 1373–1383.
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Gadea A., Le Devehat F., Le Lamer A.-C., Charrier M., Boustie J. (2015). Lichens chemestry and grazing by the sub-antarctic land snail Notodiscus hookeri. 2ème symposium International AFERP-STOLON “Biodiversité et Substances Naturelles”, Lyon, France, 15-17/07/2015.
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Gorodetskaya I V, Kneifel S, Maahn M, Thiery W, Schween J H, Mangold A, Crewell S, Van Lipzig N P M, . (2015). Cloud and precipitation properties from ground-based remote-sensing instruments in East Antarctica
. The Cryosphere, 9(1), 285–304.
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Genthon C, Six D, Scarchilli C, Ciardini V, Frezzotti M, . (2016). Meteorological and snow accumulation gradients across Dome C, East Antarctic plateau
. International Journal of Climatology, 36(1), 455–466.
Abstract: In situ observations show that snow accumulation is ~10% larger 25 km north than south of the summit of Dome C on the east antarctic plateau. The mean wind direction is southerly. Although a slight slope-related diverging katabatic flow component is detectable, the area is an essentially flat (~10 m elevation change or less) homogeneous snow surface. The European Center for Medium-range Weather Forecasts meteorological analyses data reproduce a significant accumulation gradient and suggest that 90% of the the mean accumulation results from the 25% largest precipitation events. During these events, air masses originate from coastal areas in the north rather than from inland in the south. Radiative cooling condensation occurs on the way across the dome and as the moisture reservoir is depleted less snow is dumped 25 km south than north, with little direct impact from the local (50-km scale) topography. Air masses are warmer on average, and warmer north than south, when originating from the coast. This marginally affects the mean temperature gradients. The moisture gradients are more affected because moisture is nonlinearly related to temperature: the mean atmospheric moisture is larger north than south. Significant meteorological and hydrological gradients over such relatively small distances (50 km) over locally flat region may be an issue when interpreting ice cores: although cores are drilled at the top of domes and ridges where the slopes and elevation gradients are minimal, they sample small surfaces in areas affected by significant meteorological and hydrological spatial gradients.
Programme: 411,1013
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Della Penna Alice, De Monte Silvia, Kestenare Elodie, Guinet Christophe, d'Ovidio Francesco, . (2015). Quasi-planktonic behavior of foraging top marine predators.
. Scientific reports, 5, 18063.
Abstract: Monitoring marine top predators is fundamental for assessing the health and functioning of open ocean ecosystems. Although recently tracking observations have substantially increased, factors determining the horizontal exploration of the ocean by marine predators are still largely unknown, especially at the scale of behavioral switches (1-100 km, days-weeks). It is commonly assumed that the influence of water movement can be neglected for animals capable of swimming faster than the current. Here, we challenge this assumption by combining the use of biologging (GPS and accelerometry), satellite altimetry and in-situ oceanographic data (ADCP and drifting buoys) to investigate the effect of the mesoscale ocean dynamics on a marine predator, the southern elephant seal. A Lagrangian approach reveals that trajectories of elephant seals are characterized by quasi-planktonic bouts where the animals are horizontally drifting. These bouts correspond to periods of increased foraging effort, indicating that in the quasi-planktonic conditions energy is allocated to diving and chasing, rather than in horizontal search of favourable grounds. These results suggest that mesoscale features like eddies and fronts may act as a focal points for trophic interactions not only by bottom-up modulation of nutrient injection, but also by directly entraining horizontal displacements of the upper trophic levels.
Programme: 109
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