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Christophe Leroy-Dos Santos, Mathieu Casado, Frédéric Prié, Olivier Jossoud, Erik Kerstel, Morgane Farradèche, Samir Kassi, Elise Fourré, Amaëlle Landais. (2021). A dedicated robust instrument for water vapor generation at low humidity for use with a laser water isotope analyzer in cold and dry polar regions (Vol. 14). Bachelor's thesis, , .
Abstract: Obtaining Precise Continuous Measurements Of Water Vapor Isotopic Composition In Dry Places (Polar Or High-altitude Regions) Is An Important Challenge. The Current Limitation Is The Strong Influence Of Humidity On The Measured Water Isotopic Composition By Laser Spectroscopy Instruments For Low Humidity Levels (Below 3000 Ppmv). This Problem Is Addressed By Determining The Relationships Between Humidity And Measured δ18o And δD Of Known Water Standards. Here, We Present The Development Of A Robust Field Instrument Able To Generate Water Vapor, Down To 70 Ppmv, At Very Stable Humidity Levels (Average 1σ Lower Than 10 Ppmv). This Instrument, Operated By A Raspberry Interface, Can Be Coupled To A Commercial Laser Spectroscopy Instrument. We Checked The Stability Of The System As Well As Its Accuracy When Expressing The Measured Isotopic Composition Of Water Vapor On The Vsmow–slap (Vienna Standard Mean Ocean Water – Standard Light Antarctic Precipitation) Scale. It Proved To Be Highly Stable During Autonomous Operation Over More Than 1 Year At The East Antarctic Concordia And Dumont D'urville Stations.
Programme: 1110,1169,1205
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Daniel C. Jones, Filipe R. Ceia, Eugene Murphy, Karine Delord, Robert W. Furness, Ariane Verdy, Matthew Mazloff, Richard A. Phillips, Paul M. Sagar, Jean-Baptiste Sallée, Ben Schreiber, David R. Thompson, Leigh G. Torres, Philip J. Underwood, Henri Weimerskirch, José C. Xavier. (2021). Untangling local and remote influences in two major petrel habitats in the oligotrophic Southern Ocean (Vol. 27).
Abstract: Ocean circulation connects geographically distinct ecosystems across a wide range of spatial and temporal scales via exchanges of physical and biogeochemical properties. Remote oceanographic processes can be especially important for ecosystems in the Southern Ocean, where the Antarctic Circumpolar Current transports properties across ocean basins through both advection and mixing. Recent tracking studies have indicated the existence of two large-scale, open ocean habitats in the Southern Ocean used by grey petrels (Procellaria cinerea) from two populations (i.e., Kerguelen and Antipodes islands) during their nonbreeding season for extended periods during austral summer (i.e., October to February). In this work, we use a novel combination of large-scale oceanographic observations, surface drifter data, satellite-derived primary productivity, numerical adjoint sensitivity experiments, and output from a biogeochemical state estimate to examine local and remote influences on these grey petrel habitats. Our aim is to understand the oceanographic features that control these isolated foraging areas and to evaluate their ecological value as oligotrophic open ocean habitats. We estimate the minimum local primary productivity required to support these populations to be much <1% of the estimated local primary productivity. The region in the southeast Indian Ocean used by the birds from Kerguelen is connected by circulation to the productive Kerguelen shelf. In contrast, the region in the south-central Pacific Ocean used by seabirds from the Antipodes is relatively isolated suggesting it is more influenced by local factors or the cumulative effects of many seasonal cycles. This work exemplifies the potential use of predator distributions and oceanographic data to highlight areas of the open ocean that may be more dynamic and productive than previously thought. Our results highlight the need to consider advective connections between ecosystems in the Southern Ocean and to re-evaluate the ecological relevance of oligotrophic Southern Ocean regions from a conservation perspective.
Keywords: Antarctic Circumpolar Current (ACC) biogeography conservation grey petrels high seas hotspot open ocean primary productivity Procellaria cinerea seabirds
Programme: 109
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Alberto Baudena, Enrico Ser-Giacomi, Donatella D’Onofrio, Xavier Capet, Cedric Cotté, Yves Cherel, Francesco D’Ovidio. (2021). Fine-scale structures as spots of increased fish concentration in the open ocean (Vol. 11).
Abstract: Oceanic frontal zones have been shown to deeply influence the distribution of primary producers and, at the other extreme of the trophic web, top predators. However, the relationship between these structures and intermediate trophic levels is much more obscure. In this paper we address this knowledge gap by comparing acoustic measurements of mesopelagic fish concentrations to satellite-derived fine-scale Lagrangian Coherent Structures in the Indian sector of the Southern Ocean. First, we demonstrate that higher fish concentrations occur more frequently in correspondence with strong Lagrangian Coherent Structures. Secondly, we illustrate that, while increased fish densities are more likely to be observed over these structures, the presence of a fine-scale feature does not imply a concomitant fish accumulation, as other factors affect fish distribution. Thirdly, we show that, when only chlorophyll-rich waters are considered, front intensity modulates significantly more the local fish concentration. Finally, we discuss a model representing fish movement along Lagrangian features, specifically built for mid-trophic levels. Its results, obtained with realistic parameters, are qualitatively consistent with the observations and the spatio-temporal scales analysed. Overall, these findings may help to integrate intermediate trophic levels in trophic models, which can ultimately support management and conservation policies.
Keywords: Fisheries Marine biology Physical oceanography
Programme: 109
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Jean Roger, Bernard Pelletier, Maxime Duphil, Jérôme Lefèvre, Jérôme Aucan, Pierre Lebellegard, Bruce Thomas, Céline Bachelier, David Varillon. (2021). The Mw 7.5 Tadine (Maré, Loyalty Is.) earthquake and related tsunami of December 5, 2018: implications for tsunami hazard assessment in New Caledonia.
Abstract: On The 5th Of December 2018, A Magnitude Mw 7.5 Earthquake Occurred Southeast Of Maré, An Island Of The Loyalty Archipelago, New Caledonia. This Earthquake Is Located At The Junction Between The Plunging Loyalty Ridge And The Southernmost Vanuatu Arc, In A Tectonically Very Active Area Regularly Subjected To Strong Seismic Crises And Events Higher Than Magnitude 7 And Up To 8. Widely Felt In New Caledonia It Has Been Immediately Followed By A Tsunami Warning, Confirmed Shortly After By A First Wave Arrival At The Loyalty Islands Tide Gauges (Maré And Lifou), Then Along The East Coast Of Grande Terre Of New Caledonia And In Several Islands Of The Vanuatu Archipelago. Seafloor Initial Deformation Linked To Tsunami Generation Has Been Modeled With Most Numerical Code Using Earthquake Parameters Available From Seismic Observatories. Then The Wave Propagation Has Been Modeled Using Schism, Another Modelling Code Solving The Shallow Water Equations On An Unstructured Grid Based On A New Regional Dem Of ~180 M Resolution And Allowing Refinement In Many Critical Areas. Finally, The Results Have Been Compared To Tide Gauge Records, Field Observations And Testimonials From 2018. The Arrival Times, Wave Amplitude And Polarities Present Good Similarities, Especially In Far-field Locations (Hienghène, Port-vila And Poindimié). Maximum Wave Heights And Energy Maps For Two Different Scenarios Highlight The Fact That The Orientation Of The Source (Strike Of The Rupture) Played An Important Role, Focusing The Maximum Energy Path Of The Tsunami South Of Grande-terre And The Isle Of Pines. However, Both Scenarios Indicate Similar Propagation Toward Aneityum, Vanuatu Southernmost Island, The Bathymetry Acting Like A Waveguide. This Study Has A Significant Implication In Tsunami Hazard Mitigation In New Caledonia As It Helps To Validate The Modelling Code And Process Used To Prepare A Scenarios Database For Warning And Coastal Evacuation.
Programme: 133
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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. (2021). Surface ocean microbiota determine cloud precursors (Vol. 11).
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.
Keywords: Atmospheric science Marine biology
Programme: 1187
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Charlène Guillaumot. (2021). Modelling the response of Antarctic marine species to environmental changes. Methods, applications and limitations. /// Modéliser la réponse des espèces marines antarctiques aux changements environnementaux. Méthodes, applications et limites. Bachelor's thesis, , .
Abstract: Parmi les outils qui permettent de mieux comprendre les systèmes naturels, la modélisation écologique a connu un essor particulièrement important depuis une vingtaine d’années. Les modèles écologiques, représentation simplifiée d’une réalité complexe, permettent de mettre en avant les facteurs environnementaux qui déterminent la niche écologique des espèces et de mieux comprendre leur réponse aux changements de l’environnement. Dans le cas des faunes marines antarctiques, la modélisation écologique fait face à plusieurs défis méthodologiques. Les jeux de données de présence des espèces sont très souvent agrégés dans le temps et dans l’espace, à proximité des stations de recherche. Ces données sont souvent trop peu nombreuses pour caractériser l’espace environnemental occupé par les espèces ainsi que leur physiologie. Enfin, les jeux de données environnementales manquent encore de précision pour finement représenter la complexité des habitats marins. Dans ces conditions, est-il possible de générer des modèles performants et justes à l’échelle de l’océan Austral ? Quelles sont les approches possibles et leurs limites ? Comment améliorer les méthodes afin de générer de meilleurs modèles ? Au cours de ce travail de thèse, trois types de modèles ont été étudiés et leurs performances évaluées. (1) Les modèles physiologiques de type DEB (Dynamic Energy Budget) simulent la manière dont l’environnement abiotique influe sur le métabolisme des individus et proposent une représentation de la niche fondamentale des espèces. (2) Les modèles de distribution d’espèces (SDMs pour Species Distribution Models) prédisent la probabilité de distribution des espèces en étudiant la relation spatiale entre données de présence et environnement. Ils proposent une représentation de la niche réalisée des espèces. Enfin (3), les modèles de dispersion de type lagrangien prédisent le mouvement de propagules dans les masses d’eau. Les résultats montrent que les modèles physiologiques réussissent à simuler les variations métaboliques des espèces antarctiques en fonction de l’environnement et à prédire les dynamiques de populations. Cependant, davantage de données sont nécessaires pour pouvoir caractériser finement les différences physiologiques entre populations et évaluer correctement les modèles. Les résultats obtenus pour les SDMs montrent que les modèles générés à l’échelle de l’océan Austral et leurs prédictions futures ne sont pas fiables du fait du manque de données disponibles pour caractériser l’espace occupé par les espèces, du manque de précision des scénarios climatiques futurs et de l’impossibilité d’évaluer les modèles. De plus, les modèles extrapolent sur une très grande proportion de l’espace projeté. L’apport d’information complémentaire sur les limites physiologiques des espèces (observations, résultats d’expériences, sorties de modèles physiologiques) permet de réduire l’extrapolation et d’augmenter la capacité des modèles à décrire la niche réalisée des espèces. L’agrégation spatiale des données, qui influençait les prédictions et l’évaluation des modèles a également pu être corrigée. Enfin, les modèles de dispersion ont montré un potentiel intéressant pour révéler le rôle des barrières géographiques ou à l’inverse, la connectivité spatiale, mais également le lien existant entre distribution, physiologie et histoire phylogénétique des espèces. Ce travail de thèse propose de nombreux conseils et fournit des codes annotés parfois sous forme de tutoriels, afin de constituer une aide utile aux futurs travaux de modélisation sur les espèces marines antarctiques.
Programme: 688,1044
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Mark A. Hindell, Clive R. McMahon, Ian Jonsen, Robert Harcourt, Fernando Arce, Christophe Guinet. (2021). Inter- and intrasex habitat partitioning in the highly dimorphic southern elephant seal (Vol. 11). Bachelor's thesis, , .
Abstract: Partitioning resources is a key mechanism for avoiding intraspecific competition and maximizing individual energy gain. However, in sexually dimorphic species it is difficult to discern if partitioning is due to competition or the different resource needs of morphologically distinct individuals. In the highly dimorphic southern elephant seal, there are intersexual differences in habitat use; at Iles Kerguelen, males predominantly use shelf waters, while females use deeper oceanic waters. There are equally marked intrasexual differences, with some males using the nearby Kerguelen Plateau, and others using the much more distant Antarctic continental shelf ( 2,000 km away). We used this combination of inter and intrasexual behavior to test two hypotheses regarding habitat partitioning in highly dimorphic species. (a) that intersexual differences in habitat use will not appear until the seals diverge in body size and (b) that some habitats have higher rates of energy return than others. In particular, that the Antarctic shelf would provide higher energy returns than the Kerguelen Shelf, to offset the greater cost of travel. We quantified the habitat use of 187 southern elephant seals (102 adult females and 85 subadult males). The seals in the two groups were the same size ( 2.4 m) removing the confounding effect of body size. We found that the intersexual differences in habitat use existed before the divergence in body size. Also, we found that the amount of energy gained was the same in all of the major habitats. This suggests that the use of shelf habitats by males is innate, and a trade-off between the need to access the large benthic prey available on shelf waters, against the higher risk of predation there. Intrasexual differences in habitat use are another trade-off; although there are fewer predators on the Antarctic shelf, it is subject to considerable interannual fluctuations in sea-ice extent. In contrast, the Kerguelen Plateau presents more consistent foraging opportunities, but contains higher levels of predation. Habitat partitioning in this highly dimorphic species is therefore the result of complex interplay of life history strategies, environmental conditions and predation pressure.
Keywords: Antarctic Shelf foraging and diving behavior Kerguelen Plateau mid-year haul out predation risk Southern Ocean
Programme: 109,1201
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Viblanc Va, Stier A, Bize P, Schull Q, Criscuolo F, Groscolas R, Robin Jp. (2021). The ecophysiology of king penguins : responses to a fluctuating environment. Bachelor's thesis, , .
Abstract: Penguins are sea...birds. These highly evolved marine predators thrive in the oceanic habitat. Yet, they are conflicted – confronted to the duality of a life spent partly at sea, partly on-land. This life style has them subject to a number of very different ecological pressures. The ECONERGY polar project (IPEV #119) seeks to understand how king penguin cope with the constraints they face while living on-land, and the underlying physiological adaptations that allow them to do so. This includes studies dealing with fasting, parasites, predators, aggressive neighbors, climate and human disturbance. I will present some of the advances our project has made over the past decades, and where we will proceed in the years to come with a new project. We aim to understand bird stress from an integrative perspective, building a long-term observatory of penguin physiological responses to a changing world, and determining how breeding performances on land and foraging performances at sea are related.
Programme: 119
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Amalie Vigdel Ask, Bjørn Munro Jenssen, Sabrina Tartu, Frédéric Angelier, Olivier Chastel, Geir Wing Gabrielsen. (2021). Per- and Polyfluoroalkyl Substances Are Positively Associated with Thyroid Hormones in an Arctic Seabird (Vol. 40).
Abstract: Per- and polyfluoroalkyl substances (PFAS) are associated with several disrupted physiological and endocrine parameters. Regarding endocrine mechanisms, laboratory studies suggest that PFAS could disrupt the thyroid hormone system and alter circulating thyroid hormone concentrations. Thyroid hormones play a ubiquitous role—controlling thermoregulation, metabolism, and reproduction. However, evidence for disruption of thyroid hormones by PFAS remains scarce in wildlife. The present study investigated the associations between concentrations of PFAS, thyroid hormones, and body condition in an arctic seabird, the black-legged kittiwake (Rissa tridactyla). We collected blood from kittiwakes sampled in Svalbard, Norway (2013 and 2014). Plasma samples were analyzed for total thyroxine (TT4) and total triiodothyronine (TT3) concentrations; detected PFAS included branched and linear (lin) C8 perfluoroalkyl sulfonates (i.e., perfluoroctane sulfonate [PFOS]) and C9-C14 perfluoroalkyl carboxylates (PFCAs). The dominant PFAS in the kittiwakes were linPFOS and C11- and C13-PFCAs. Generally, male kittiwakes had higher concentrations of PFAS than females. We observed positive correlations between linPFOS, C10-PFCA, and TT4 in males, whereas in females C12-14-PFCAs were positively correlated to TT3. Interestingly, we observed contrasted correlations between PFAS and body condition; the direction of the relationship was sex-dependent. Although these results show relationships between PFAS and circulating thyroid hormone concentrations in kittiwakes, the study design does not allow for concluding on causal relationships related to effects of PFAS on the thyroid hormone system. Future experimental research is required to quantify this impact of PFAS on the biology of kittiwakes. The apparently different associations among PFAS and body condition for males and females are puzzling, and more research is required. Environ Toxicol Chem 2021;40:820–831. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
Keywords: Avian toxicity Ecotoxicology Endocrine-disrupting compounds Per- and polyfluoroalkyl substance Thyroid hormones
Programme: 330
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Julien Jumelet, Florent Tencé, Alain Sarkissian, Slimane Bekki, Philippe Keckhut. (2021). 10 years of Polar Stratospheric Clouds lidar measurements at the French antarctic station Dumont d'Urville.
Abstract: Polar Stratospheric Clouds (PSCs) play a primary role in polar stratospheric ozone depletion processes. Aside from recent improvements in both spaceborne monitoring as well as investigations on microphysics and modeling, there are still caveats on building a comprehensive picture of the PSC particle population, especially considering the fine optical signatures of some particles. In that regard, groundbased instruments provide fine and long term reference measurements that complement the global spaceborne coverage. Operated at the French antarctic station Dumont d’Urville (DDU) in the frame of the international Network for the Detection of Atmospheric Composition Change (NDACC), the Rayleigh/Mie/Raman lidar provides over the years a solid dataset to feed both process and classification studies, by monitoring cloud and aerosol occurrences in the upper troposphere and lower stratosphere. Located on antarctic shore (66°S – 140°E), the station has a privileged access to polar vortex dynamics. Measurements are weather-dependent with a yearly average of 130 nights of monitoring. Expected PSC formation temperatures are used to evaluate the whole PSC season occurrence statistics. We hereby present a consolidated dataset from 10 years of lidar measurements using the 532nm backscatter ratio, the aerosol depolarisation and local atmospheric conditions to help in building an aerosol/cloud classification. Overall, the DDU PSC pattern is very consistent with expected typical temperature controlled thresholds. Supercooled Ternary Solution (STS) particles are the most observed particle type, closely followed by Nitric Acid Trihydrate (NAT). ICE clouds are more rarely observed. The measurements also feature significant and detailed signatures of various aerosols events having reached the polar antarctic stratosphere, like the Calbuco eruption (2015) or the 2 australian wildfires episodes (2009 and 2019). We aim at refining the identification of those aerosols to include their impact in the scope of the scientific questions studied at DDU.
Programme: 209
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