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Author Éric Bernard, Jean-Michel Friedt, Madeleine Griselin doi  openurl
  Title (up) Snowcover Survey over an Arctic Glacier Forefield: Contribution of Photogrammetry to Identify “Icing” Variability and Processes Type Journal
  Year 2021 Publication Remote Sensing Abbreviated Journal  
  Volume 13 Issue 10 Pages 1978  
  Keywords arctic cryosphere moraine photogrammetry snow water equivalent snowcover spatial dynamics UAV-SfM  
  Abstract The global climate shift currently underway has significant impacts on both the quality and quantity of snow precipitation. This directly influences the spatial variability of the snowpack as well as cumulative snow height. Contemporary glacier retreat reorganizes periglacial morphology: while the glacier area decreases, the moraine area increases. The latter is becoming a new water storage potential that is almost as important as the glacier itself, but with considerably more complex topography. Hence, this work fills one of the missing variables of the hydrological budget equation of an arctic glacier basin by providing an estimate of the snow water equivalent (SWE) of the moraine contribution. Such a result is achieved by investigating Structure from Motion (SfM) image processing that is applied to pictures collected from an Unmanned Aerial Vehicle (UAV) as a method for producing snow depth maps over the proglacial moraine area. Several UAV campaigns were carried out on a small glacial basin in Spitsbergen (Arctic): the measurements were made at the maximum snow accumulation season (late April), while the reference topography maps were acquired at the end of the hydrological year (late September) when the moraine is mostly free of snow. The snow depth is determined from Digital Surface Model (DSM) subtraction. Utilizing dedicated and natural ground control points for relative positioning of the DSMs, the relative DSM georeferencing with sub-meter accuracy removes the main source of uncertainty when assessing snow depth. For areas where snow is deposited on bare rock surfaces, the correlation between avalanche probe in-situ snow depth measurements and DSM differences is excellent. Differences in ice covered areas between the two measurement techniques are attributed to the different quantities measured: while the former only measures snow accumulation, the latter includes all of the ice accumulation during winter through which the probe cannot penetrate, in addition to the snow cover. When such inconsistencies are observed, icing thicknesses are the source of the discrepancy that is observed between avalanche probe snow cover depth measurements and differences of DSMs.  
  Programme 1108  
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  Notes Approved yes  
  Call Number Serial 4442  
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Author Florian Orgeret, Ryan R. Reisinger, Tegan Carpenter-Kling, Danielle Z. Keys, Alexandre Corbeau, Charles-André Bost, Henri Weimerskirch, Pierre A. Pistorius file  doi
openurl 
  Title (up) Spatial segregation in a sexually dimorphic central place forager: Competitive exclusion or niche divergence? Type Journal
  Year 2021 Publication Journal of Animal Ecology Abbreviated Journal  
  Volume 90 Issue 10 Pages 2404-2420  
  Keywords bio-logging central place foraging ecological niche theory intraspecific competition kernel density estimates resource selection functions sexual segregation wandering albatross  
  Abstract Sexual competition is increasingly recognized as an important selective pressure driving species distributions. However, few studies have investigated the relative importance of interpopulation versus intrapopulation competition in relation to habitat availability and selection. To explain spatial segregation between sexes that often occurs in non-territorial and central place foragers, such as seabirds, two hypotheses are commonly used. The ‘competitive exclusion’ hypothesis states that dominant individuals should exclude subordinate individuals through direct competition, whereas the ‘niche divergence’ hypothesis states that segregation occurs due to past competition and habitat specialization. We tested these hypotheses in two populations of an extreme wide-ranging and sexually dimorphic seabird, investigating the relative role of intrapopulation and interpopulation competition in influencing sex-specific distribution and habitat preferences. Using GPS loggers, we tracked 192 wandering albatrosses Diomedea exulans during four consecutive years (2016–2019), from two neighbouring populations in the Southern Ocean (Prince Edward and Crozet archipelagos). We simulated pseudo-tracks to create a null spatial distribution and used Kernel Density Estimates (KDE) and Resource Selection Functions (RSF) to distinguish the relative importance of within- versus between-population competition. Kernel Density Estimates showed that only intrapopulation sexual segregation was significant for each monitoring year, and that tracks between the two colonies resulted in greater overlap than expected from the null distribution, especially for the females. RSF confirmed these results and highlighted key at-sea foraging areas, even if the estimated of at-sea densities were extremely low. These differences in selected areas between sites and sexes were, however, associated with high interannual variability in habitat preferences, with no clear specific preferences per site and sex. Our results suggest that even with low at-sea population densities, historic intrapopulation competition in wide-ranging seabirds may have led to sexual dimorphism and niche specialization, favouring the ‘niche divergence’ hypothesis. In this study, we provide a protocol to study competition within as well as between populations of central place foragers. This is relevant for understanding their distribution patterns and population regulation, which could potentially improve management of threatened populations.  
  Programme 109,394  
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  Corporate Author Thesis Bachelor's thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1365-2656 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8093  
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Author Lucie Aulus-Giacosa openurl 
  Title (up) Spatio-temporal evolution of life history traits related to dispersal. Brown trout (Salmo trutta L.) colonization of the sub-Antarctic Kerguelen Islands. // Evolution de l'anadromie chez la truite commune (Salmo trutta) L. dans le cadre de l'expansion des populations introduites dans les îles Kerguelen. Type Thesis
  Year 2021 Publication Thèse de doctorat en Physiologie et Biologie des Organismes – Populations -Interactions Abbreviated Journal  
  Volume Issue Pages  
  Keywords  
  Abstract Grâce à ses capacités dispersives et adaptatives, la truite commune (Salmo trutta L.), poisson anadrome facultatif, est un bon candidat à la colonisation de nouveaux milieux. L'introduction de l'espèce dans les années 1950 dans les îles subantarctiques de Kerguelen fournit un modèle d'étude unique pour comprendre les causes et les mécanismes de la dispersion, grâce à l'étude des traits d'histoire de vie en lien avec la migration (e.g. croissance, âge à la migration). L'étude de leur évolution temporelle le long d'un front de colonisation est le cœur de ce travail de thèse. A travers l’étude des écailles recueillies dans le cadre de ce programme à long terme, les histoires de vie de près de 5000 poissons ont été reconstruites. Ce travail démontre l’importance de la méthodologie utilisée afin de reconstruire les traits de vie individuel. La modélisation de l’évolution de la croissance en eau douce, de la taille à l’âge et de l’âge à la première migration démontre que des processus évolutifs sont en œuvre dans les populations en expansion. Notamment, le ralentissement de la croissance avec le temps ainsi que la diminution de la taille à l’âge le long du front de colonisation laissent à penser que la capacité de dispersion diminue à mesure que les populations sont en marges de la zone d’expansion. L’évolution de la valeur seuil à la première migration confirme ce résultat, et illustre l’importance de la plasticité phénotypique et de l’adaptation locale dans le choix de la tactique migratoire. Toutefois, l’approche menée dans ce manuscrit se concentre sur l’évolution de la migration, et bénéficierait de l’étude de l’évolution conjointe des traits impliqués dans la valeur sélective (balance coûts-bénéfices), tels que la reproduction, ou la croissance en mer.  
  Programme 1041  
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  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8354  
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Author Anika Immer, Thomas Merkling, Olivier Chastel, Scott A. Hatch, Etienne Danchin, Pierrick Blanchard, Sarah Leclaire doi  isbn
openurl 
  Title (up) Spying on your neighbours? Social information affects timing of breeding and stress hormone levels in a colonial seabird Type Journal
  Year 2021 Publication Evolutionary Ecology Abbreviated Journal  
  Volume 35 Issue 3 Pages 463-481  
  Keywords  
  Abstract A good overlap between offspring energetic requirements and availability of resources is required for successful reproduction. Accordingly, individuals from numerous species fine-tune their timing of breeding by integrating cues that predict environmental conditions during the offspring period. Besides acquiring information from their direct interaction with the environment (personal information), individuals can integrate information by observing the behaviours or performance of others (social information). The use of social information is often beneficial because the accumulated knowledge of conspecifics may represent a source of information more reliable than the intrinsically more limited personal information. However, although social information constitutes the major source of information in a wide range of contexts, studies investigating its use in the context of timing of breeding are scarce. We investigated whether black-legged kittiwakes (Rissa tridactyla) used social information to adjust the timing of egg-laying. We manipulated social information using a food-supplementation experiment, known to advance kittiwakes' reproductive phenology. We expected food-supplemented and unsupplemented pairs to delay and advance, respectively, their timing of laying when surrounded by a majority of neighbours from the opposite food-treatment. However, both unsupplemented and food-supplemented kittiwakes delayed egg-laying when surrounded by a higher proportion of neighbours from the opposite food-treatment. This result shows that kittiwakes use social information to time egg-laying, but that it is not used to match the seasonal peak of food availability. We suggest that when social and personal cues give contradictory environmental information, individuals may benefit from delaying laying to gather more information to make better decisions about investment into eggs. Further, we explored a potential proximate mechanism for the pattern we report. We show that baseline corticosterone, known to mediate reproductive decisions, was lower in unsupplemented females facing a higher proportion of food-supplemented neighbours. Altogether, our results suggest that to fine-tune their timing of laying, kittiwakes use complex decision-making processes in which social and personal information interplay.  
  Programme 1162  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1573-8477 ISBN 1573-8477 Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8245  
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Author Benjamin Merkel, Sébastien Descamps, Nigel G. Yoccoz, David Grémillet, Per Fauchald, Jóhannis Danielsen, Francis Daunt, Kjell Einar Erikstad, Aleksey V. Ezhov, Mike P. Harris, Maria Gavrilo, Svein-Håkon Lorentsen, Tone K. Reiertsen, Geir H. Systad, Thorkell Lindberg Thórarinsson, Sarah Wanless, Hallvard Strøm doi  openurl
  Title (up) Strong migratory connectivity across meta-populations of sympatric North Atlantic seabirds Type Journal
  Year 2021 Publication Marine Ecology Progress Series Abbreviated Journal  
  Volume SEA Issue Pages  
  Keywords Environmental niche Inter-population mixing Large-scale spatiotemporal dynamics Light-level geolocation Murres Population spread Seasonality  
  Abstract Identifying drivers of population trends in migratory species is difficult, as they can face many stressors while moving through different areas and environments during the annual cycle. To understand the potential of migrants to adjust to perturbations, it is critical to study the connection of different areas used by different populations during the annual cycle (i.e. migratory connectivity). Using a large-scale tracking data set of 662 individual seabirds from 2 sympatric auk meta-populations (common guillemots Uria aalge and Brünnich’s guillemots U. lomvia) breeding in 12 colonies throughout the Northeast Atlantic, we estimated migratory connectivity in seasonal space use as well as occupied environmental niches. We found strong migratory connectivity, within and between species. This was apparent through a combination of seasonal space use and occupied environmental niches. Brünnich’s guillemot populations grouped into 2 and common guillemot populations into 5 previously undescribed spatiotemporal clusters. Common guillemot populations clustered in accordance with the variable population trends exhibited by the species, while Brünnich’s guillemot populations are declining everywhere where known within the study area. Individuals from different breeding populations in both species were clustered in their space and environmental use, utilising only a fraction of the potential species-wide range. Further, space use varied among seasons, emphasising the variable constraints faced by both species during the different stages of their annual cycle. Our study highlights that considering spatiotemporal dynamics, not only in space but also in occupied environmental niches, improves our understanding of migratory connectivity and thus population vulnerability in the context of global change.  
  Programme 388  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0171-8630, 1616-1599 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8027  
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Author Vallas B. openurl 
  Title (up) Structuration spatiale et temporelle des colonies de manchots royaux (Aptenodytes patagonicus) Type Thesis
  Year 2021 Publication Mémoires de diplôme de l'EPHE en SVT Abbreviated Journal  
  Volume Issue Pages  
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  Abstract  
  Programme 137  
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  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8717  
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Author G. Hubert, S. Aubry doi  openurl
  Title (up) Study of the Impact of Past Extreme Solar Events on the Modern Air Traffic Type Journal
  Year 2021 Publication Space Weather Abbreviated Journal  
  Volume 19 Issue 4 Pages e2020SW002665  
  Keywords  
  Abstract The ancient solar energetic particle (SEP) events of 774/775 CE and 993/994 CE were characterized thanks to radionuclide productions stored in environmental archives as ice cores or tree rings. Primary cosmic ray spectra deduced from these cosmogenic isotope data indicate that the impact of these extreme SEP events would have been much more significant than any of the ones observed during the modern era. However, the impact of these should be studied more accurately in the framework of the ambient dose equivalent impacting aircrew and passengers in the air traffic context by considering physical parameters such as time profile or anisotropy properties. In this study, the impact that 774/775 CE and 993/994 CE past extreme SEP events could have had on modern air traffic is discussed. Possible event spectra for these ancient events are derived from the spectra ground-level enhancement (GLE) 5 and GLE 69, which have been observed during the modern era and have been widely studied/characterized using measurements. The investigations include the impact of the SEP activity on ambient dose equivalent, including detailed analyses considering route, airplane characteristics (departure, arrival, continent, airplane type), and the time occurrence of the SEP event. Statistical analyses show that additional dose levels can reach values on the order of 70 mSv, which is absolutely significant considering the current air traffic recommendations. The orders of magnitude of the ambient dose equivalent induced during past extreme SEP events raises a number of issues, both for aircrews and for avionics hardware. This study demonstrates that simulations can be useful for the evaluation of risks in case of extreme SEP events.  
  Programme 1112  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1542-7390 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 7934  
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Author Afsaneh Mohammadzaheri, Karin Sigloch, Kasra Hosseini, Mitchell G. Mihalynuk doi  openurl
  Title (up) Subducted Lithosphere Under South America From Multifrequency P Wave Tomography Type Journal
  Year 2021 Publication Journal of Geophysical Research: Solid Earth Abbreviated Journal  
  Volume 126 Issue 6 Pages e2020JB020704  
  Keywords Andes intra-arc intra-oceanic subduction seismic tomography South America structure of the mantel  
  Abstract We analyze mantle structure under South America in the DETOX-P1 seismic tomography model, a global-scale, multifrequency inversion of teleseismic P waves. DETOX-P1 inverts the most extensive data set of broadband, waveform-based traveltime measurements to date, complemented by analyst-picked traveltimes from the ISC-EHB catalog. The mantle under South America is sampled by ∼665,000 cross-correlation traveltimes measured on 529 South American broadband stations and on 5,389 stations elsewhere. By their locations, depths, and geometries, we distinguish four high-velocity provinces under South America, interpreted as subducted lithosphere (“slabs”). The deepest (∼1,800–1,200 km depth) and shallowest (<600 km) slab provinces are observed beneath the Andean Cordillera near the continent’s northwest coast. At intermediate depths (1,200–900 km, 900–600 km), two slab provinces are observed farther east, under Brazil, Bolivia and Venezuela, with links to the Caribbean. We interpret the slabs relative to South America’s paleo-position over time, exploring the hypothesis that slabs sank essentially vertically after widening by viscous deformation in the mantle transition zone. The shallowest slab province carries the geometric imprint of the continental margin and represents ocean-beneath-continent subduction during Cenozoic times. The deepest, farthest west slab complex formed under intra-oceanic trenches during late Jurassic and Cretaceous times, far west of South America’s paleo-position adjoined to Africa. The two intermediate slab complexes record the Cretaceous transition from westward intra-oceanic subduction to eastward subduction beneath South America. This geophysical inference matches geologic records of the transition from Jura-Cretaceous, extensional “intra-arc” basins to basin inversion and onset of the modern Andean arc ∼85 Ma.  
  Programme 133  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2169-9356 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 7991  
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Author Andreas Richter, Alexey A. Ekaykin, Matthias O. Willen, Vladimir Ya. Lipenkov, Andreas Groh, Sergey V. Popov, Mirko Scheinert, Martin Horwath, Reinhard Dietrich doi  openurl
  Title (up) Surface Mass Balance Models Vs. Stake Observations: A Comparison in the Lake Vostok Region, Central East Antarctica Type Journal
  Year 2021 Publication Frontiers in Earth Science Abbreviated Journal  
  Volume 9 Issue Pages 388  
  Keywords  
  Abstract The surface mass balance (SMB) is very low over the vast East Antarctic Plateau, for example in the Vostok region, where the mean SMB is on the order of 20–35 kg m-2 a-1. The observation and modeling of spatio-temporal SMB variations are equally challenging in this environment. Stake measurements carried out in the Vostok region provide SMB observations over half a century (1970–2019). This unique data set is compared with SMB estimations of the regional climate models RACMO2.3p2 (RACMO) and MAR3.11 (MAR). We focus on the SMB variations over time scales from months to decades. The comparison requires a rigorous assessment of the uncertainty in the stake observations and the spatial scale dependence of the temporal SMB variations. Our results show that RACMO estimates of annual and multi-year SMB agree well with the observations. The regression slope between modelled and observed temporal variations is close to 1.0 for this model. SMB simulations by MAR are affected by a positive bias which amounts to 6 kg m-2 a-1 at Vostok station and 2 kg m-2 a-1 along two stake profiles between Lake Vostok and Ridge B. None of the models is capable to reproduce the seasonal distributions of SMB and precipitation. Model SMB estimates are used in assessing the ice-mass balance and sea-level contribution of the Antarctic Ice Sheet by the input-output method. Our results provide insights into the uncertainty contribution of the SMB models to such assessments.  
  Programme 411  
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  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2296-6463 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8030  
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Author Karine Sellegri, Alessia Nicosia, Evelyn Freney, Julia Uitz, Melilotus Thyssen, Gérald Grégori, Anja Engel, Birthe Zäncker, Nils Haëntjens, Sébastien Mas, David Picard, Alexia Saint-Macary, Maija Peltola, Clémence Rose, Jonathan Trueblood, Dominique Lefevre, Barbara D’Anna, Karine Desboeufs, Nicholas Meskhidze, Cécile Guieu, Cliff S. Law doi  openurl
  Title (up) Surface ocean microbiota determine cloud precursors Type Journal
  Year 2021 Publication Scientific Reports Abbreviated Journal  
  Volume 11 Issue 1 Pages 281  
  Keywords Atmospheric science Marine biology  
  Abstract One pathway by which the oceans influence climate is via the emission of sea spray that may subsequently influence cloud properties. Sea spray emissions are known to be dependent on atmospheric and oceanic physicochemical parameters, but the potential role of ocean biology on sea spray fluxes remains poorly characterized. Here we show a consistent significant relationship between seawater nanophytoplankton cell abundances and sea-spray derived Cloud Condensation Nuclei (CCN) number fluxes, generated using water from three different oceanic regions. This sensitivity of CCN number fluxes to ocean biology is currently unaccounted for in climate models yet our measurements indicate that it influences fluxes by more than one order of magnitude over the range of phytoplankton investigated.  
  Programme 1187  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2045-2322 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 7264  
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