Abstract: Identifying factors influencing survivorship is key to understanding population persistence. Although satellite telemetry is a powerful tool for studying remote animal ecology and behaviour it is rarely used for demographic studies because distinguishing the death of the animal (individual mortality) from failure of the tag (mechanical tag failure) has proven difficult. Southern elephant seals present an opportunity to separate tag failure from animal mortality thanks to the availability of large tracking datasets, broad knowledge of demographic rates, and because for these large animals, satellite tags are known not to influence mortality rates. A key rationale for investigating satellite telemetry to estimate mortality as compared to using traditional Capture-Mark-Recapture methods is the potential for obtaining spatially and temporally specific information, particularly while the animals are at sea and largely unobservable. We used satellite tag data from 182 seals from Isles Kerguelen, deployed between 2004 and 2018. Of these, 76 (42%) tags transmitted for the full post-moult foraging trip (max. 265 days for females and max. 305 days for sub-adult males) with the remaining 107 tags (58%) ceasing transmission at sea. We found that contrary to expectations, behavioural choices seem not to influence tag failure rates by mechanical means, rather the signals we detected seemed to align with previously described variation in mortality between groups. There was evidence, albeit limited, for an increase in tag failure for adult females in years with negative Southern Annular Mode (lower Southern Ocean productivity). We speculate that this increase in failure may suggest higher mortality in these years. Also, males using the Kerguelen Plateau had higher tag failure rates than those in the sea-ice zone, perhaps indicative of higher mortality. We suspect that these differences in tag failure rates between groups reflect variation in predator exposure and foraging success. This suggests satellite telemetry could be used to infer mortality events for southern elephant seals while they are at sea.

Abstract:

Abstract. Understanding the interannual variability of surface mass balance (SMB) and surface melting in Antarctica is key to quantify the signal-to-noise ratio in climate trends, identify opportunities for multi-year climate predictions and assess the ability of climate models to respond to climate variability. Here we simulate summer SMB and surface melting from 1979 to 2017 using the Regional Atmosphere Model (MAR) at 10 km resolution over the drainage basins of the Amundsen Sea glaciers in West Antarctica. Our simulations reproduce the mean present-day climate in terms of near-surface temperature (mean overestimation of 0.10 ^∘C), near-surface wind speed (mean underestimation of 0.42 m s⁻¹), and SMB (relative bias <20 % over Thwaites glacier). The simulated interannual variability of SMB and melting is also close to observation-based estimates.

For all the Amundsen glacial drainage basins, the interannual variability of summer SMB and surface melting is driven by two distinct mechanisms: high summer SMB tends to occur when the Amundsen Sea Low (ASL) is shifted southward and westward, while high summer melt rates tend to occur when ASL is shallower (i.e. anticyclonic anomaly). Both mechanisms create a northerly flow anomaly that increases moisture convergence and cloud cover over the Amundsen Sea and therefore favors snowfall and downward longwave radiation over the ice sheet. The part of interannual summer SMB variance explained by the ASL longitudinal migrations increases westward and reaches 40 % for Getz. Interannual variation in the ASL relative central pressure is the largest driver of melt rate variability, with 11 % to 21 % of explained variance (increasing westward). While high summer SMB and melt rates are both favored by positive phases of El Niño–Southern Oscillation (ENSO), the Southern Oscillation Index (SOI) only explains 5 % to 16 % of SMB or melt rate interannual variance in our simulations, with moderate statistical significance. However, the part explained by SOI in the previous austral winter is greater, suggesting that at least a part of the ENSO–SMB and ENSO–melt relationships in summer is inherited from the previous austral winter. Possible mechanisms involve sea ice advection from the Ross Sea and intrusions of circumpolar deep water combined with melt-induced ocean overturning circulation in ice shelf cavities. Finally, we do not find any correlation with the Southern Annular Mode (SAM) in summer.

Abstract: Introduction: UltraCarbonaceous Antarctic Mi-croMeteorites (UCAMMs) are interplanetary dust particles that exhibit large concentrations of organic matter with high N concentrations and extreme D/H ratios [1-4]. The mineralogy, the elemental and isotopic composition of UCAMMs indicate that they most likely originate from the cometary reservoir [1, 2, 5]. Most UCAMMs exhibit large variations on D/H, 15 N/ 14 N and 13 C/ 12 C ratios at the micron or sub-micron scale. These isotopic fractionations are carried by the organic matter and their origin is still an open question. We showed that the precursors of UCAMMs can be formed by irradiation with high energy ions of N-rich ice mixtures with hydrocarbons, a process likely to take place at the surface of icy bodies orbiting beyond a nitrogen snow line and irradiated by galactic cosmic rays [2, 6]. Recent experimental simulations showed that the irradiation itself does not induce large D fractionation, but that the refractory organic residue resulting from irradiation of isotopically heterogeneous ice mixtures can exhibit large D/H spatial variation at the micron scale [7]. We performed a new series of experiments on D, 15 N and 13 C labelled ices to study the transmission of the isotopic labelled ice layers to the irradiation-induced residue. Material and method: Irradiation experiments of ices were conducted with the low-energy beam (Irrsud, 0.5-1 MeV/n) at GANIL (Caen, France). We used the IGLIAS experimental setup [8] which allows to deposit and irradiate complex ice films mixtures on substrate windows held at temperatures ranging from 8K to 300K (Figure 1). The evolution of the ices during the irradiation was monitored in situ with a Brucker Vertex 70v Fourier transform infrared (FTIR) spectrometer. The gas mixtures deposited are controlled with a Quadrupole Mass Spectrometer (QMS). We followed the same protocol as described in [7]. We first irradiated a mixture of ices made of two equally thick layers of 14 N2-CH4 (90:10) of about 5 µm each surrounding a thin layer of isotopically labeled (in D, 13 C and 15 N) ice with a thickness of about 0.2 µm. The ice films were formed by gas injections on ZnSe windows at 8K. The thickness of the central isotopically labeled ice layer was estimated from the volume of gases injected (i.e. 2% of the total thickness). The overall thickness of the ice sandwiches (11 µm) were

Abstract: L'horizon de transformation vers la soutenabilité fondée sur le concept de résilience en écologie est décrit de manière normative dans la littérature en sciences de l'environnement ou mis en valeur à partir de cas d'étude isolés. S'ils constituent d'importantes « semences pour un bon Anthropocène » ces exemples restent encore trop rares, alors que la transformation devrait d'être entreprise à plus grande échelle et à vitesse rapide. Cette transformation nécessite urgemment d'être mise en pratique de manière plus systématique et étayée à partir de cas d'action-recherche efficaces. Pour ce faire, ceux-ci doivent être conçus et mis en œuvre grâce à de nouvelles configurations, représentations et pratiques des relations entre chercheurs et autres acteurs du territoire, publics comme privés. Autrement dit, la transformation implique un changement de gouvernance, pour aller vers une gestion adaptative des territoires, des ressources naturelles et des sociétés qui en dépendent. Elle doit faire une plus grande place aux interactions entre humains et non-humains, redéfinir en profondeur le rapport homme / nature et passer par un rééquilibrage des pouvoirs entre groupes d'acteurs et institutions, dans le processus de décision en matière de gestion environnementale. Les sciences sociales et en particulier l'anthropologie des relations homme / milieu, la sociologie politique des sciences, la sociologie politique et l'économie écologique doivent être mobilisées à cette fin, en étroite interaction avec l'écologie. Les zones-ateliers fournissent à ce titre des cas privilégiés, permettant d'opérer ce changement de paradigme, en donnant une plus grande place à l'action collective, à l'hybridation des savoirs et à l'articulation équilibrée entre intérêts divergents. Elles permettent d'identifier les paramètres déterminants pour générer de manière efficace la transformation. La ZATA, zone atelier Antarctique et Terres Australes, malgré une pression anthropique directe limitée, offre un cadre de travail privilégié pour identifier les paramètres nécessaires à la mise en œuvre d'une gouvernance propice à une gestion adaptative permettant d'augmenter la résilience des SES. La pression du changement global y est très forte, tout comme les interactions entre les diverses catégories d'acteurs et d'institutions historiquement situées. La présence des scientifiques y est très installée et mêlée à des enjeux politiques, économiques et géostratégiques auxquels contribuent la conservation de la biodiversité. A partir de deux modèles d'étude (pêcheries à Kerguelen et interactions avec la mégafaune marine/ conservation des oiseaux marins, pathogènes et dératisation à Amsterdam) faisant intervenir des chercheurs, des décideurs, des gestionnaires et les acteurs économiques dans le processus de décision multi-échelles (e.g. État français / CCAMLAR-RCTA) en termes de gestion environnementale, nous présenterons une méthode de modélisation des socio-écosystèmes en systèmes dynamiques. Les modèles produits permettent d'envisager leurs trajectoires de résilience en fonction des choix de gestion et peuvent ainsi servir d'outil d'aide à la décision et d'instrument inédit en matière de construction des mesures de gestion adaptative. Cette communication, élaborée au fil des interactions avec les gestionnaires, alliera ainsi réflexion théorique et retours sur des cas concrets pouvant permettre une montée en généralité utile pour aller vers une gouvernance des SES effective et efficace en termes de résilience et de soutenabilité.