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Author F. Bultelle, I. Boutet, S. Devin, F. Caza, Y. St-Pierre, R. Péden, P. Brousseau, P. Chan, D. Vaudry, F. Le Foll, M. Fournier, M. Auffret, B. Rocher doi  openurl
  Title Molecular response of a sub-antarctic population of the blue mussel (Mytilus edulis platensis) to a moderate thermal stress Type Journal
  Year 2021 Publication Marine Environmental Research Abbreviated Journal  
  Volume 169 Issue Pages 105393  
  Keywords (down) 2DE Abiotic stress Biomonitoring Gills Indicator species Kerguelen island Mytilus sp. qRT-PCR Temperature  
  Abstract The Kerguelen Islands (49°26′S, 69°50′E) represent a unique environment due to their geographical isolation, which protects them from anthropogenic pollution. The ability of the endemic mussel, part of the Mytilus complex, to cope with moderate heat stress was explored using omic tools. Transcripts involved in six major metabolic functions were selected and the qRT-PCR data indicated mainly changes in aerobic and anaerobic energy metabolism and stress response. Proteomic comparisons revealed a typical stress response pattern with cytoskeleton modifications and elements suggesting increased energy metabolism. Results also suggest conservation of protein homeostasis by the long-lasting presence of HSP while a general decrease in transcription is observed. The overall findings are consistent with an adaptive response to moderate stresses in mussels in good physiological condition, i.e. living in a low-impact site, and with the literature concerning this model species. Therefore, local blue mussels could be advantageously integrated into biomonitoring strategies, especially in the context of Global Change.  
  Programme 409  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0141-1136 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8256  
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Author Yushiro Fujii, Kenji Satake, Shingo Watada, Tung-Cheng Ho doi  openurl
  Title Re-examination of Slip Distribution of the 2004 Sumatra–Andaman Earthquake (Mw 9.2) by the Inversion of Tsunami Data Using Green’s Functions Corrected for Compressible Seawater Over the Elastic Earth Type Journal
  Year 2021 Publication Pure and Applied Geophysics Abbreviated Journal  
  Volume 178 Issue 12 Pages 4777-4796  
  Keywords (down) 2004 Sumatra–Andaman earthquake far-field tsunami waveform phase-corrected Green’s function slip distribution tsunami data inversion  
  Abstract We re-examined the slip distribution on faults of the 2004 Sumatra–Andaman (M 9.1 according to USGS) earthquake by the inversion of tsunami data with phase-corrected Green’s functions applied to linear long waves. The correction accounts for the effects of compressibility of seawater, elasticity of solid earth, and gravitational potential variation associated with the motion of mass to reproduce the delayed arrivals and the reversed phase of the first tsunami waves. We used sea surface height (SSH) data from satellite altimetry (SA) measurements along five tracks, and the tsunami waveforms recorded at tide gauges (TGs) and ocean bottom pressure gauges (OBPGs) in and around the Indian Ocean. The inversion results for both data sets for different rupture velocities (Vr) show that the reproducibility of the spatiotemporal SSHs and tsunami waveforms is improved by the phase corrections, although the effects are not so significant within the Indian Ocean. The best slip distribution model from joint inversion of SA, TG and OBPG data with Vr of 1.3 km/s shows the largest slips of 16–25 m off Sumatra Island, large slips of 2–11 m off the Nicobar Islands, and moderate slips of 2–6 m in the Andaman Islands. The inversion results reproduce the far-field tsunami waveforms well at distant stations even more than 13,000–25,000 km from the epicenter. The total source length is about 1400 km and the seismic moment is Mw 9.2, longer and larger than that of our previous estimates based on TG records.  
  Programme 688  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1420-9136 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8411  
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Author G. J. Sutton, C. A. Bost, A. Z. Kouzani, S. D. Adams, K. Mitchell, J. P. Y. Arnould doi  openurl
  Title Fine-scale foraging effort and efficiency of Macaroni penguins is influenced by prey type, patch density and temporal dynamics Type Journal
  Year 2021 Publication Marine Biology Abbreviated Journal  
  Volume 168 Issue 1 Pages 3  
  Keywords (down)  
  Abstract Difficulties quantifying in situ prey patch quality have limited our understanding of how marine predators respond to variation within and between patches, and throughout their foraging range. In the present study, animal-borne video, GPS, accelerometer and dive behaviour data loggers were used to investigate the fine-scale foraging behaviour of Macaroni penguins (Eudyptes chrysolophus) in response to prey type, patch density and temporal variation in diving behaviour. Individuals mainly dived during the day and utilised two strategies, targeting different prey types. Subantarctic krill (Euphausia vallentini) were consumed during deep dives, while small soft-bodied fish were captured on shallow dives or during the ascent phase of deep dives. Despite breeding in large colonies individuals seemed to be solitary foragers and did not engage with conspecifics in coordinated behaviour as seen in other group foraging penguin species. This potentially reflects the high abundance and low manoeuvrability of krill. Video data were used to validate prey capture signals in accelerometer data and a Support Vector Machine learning algorithm was developed to identify prey captures that occurred throughout the entire foraging trip. Prey capture rates indicated that Macaroni penguins continued to forage beyond the optimal give up time. However, bout-scale analysis revealed individuals terminated diving behaviour for reasons other than patch quality. These findings indicate that individuals make complex foraging decisions in relation to their proximate environment over multiple spatio-temporal scales.  
  Programme 394  
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  Series Volume Series Issue Edition  
  ISSN 1432-1793 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 2037  
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Author Guillaume Bridier, Frédéric Olivier, Laurent Chauvaud, Mikael K. Sejr, Jacques Grall doi  openurl
  Title Food source diversity, trophic plasticity, and omnivory enhance the stability of a shallow benthic food web from a high-Arctic fjord exposed to freshwater inputs Type Journal
  Year 2021 Publication Limnology and Oceanography Abbreviated Journal  
  Volume 66 Issue S1 Pages S259-S272  
  Keywords (down)  
  Abstract Under climate change, many Arctic coastal ecosystems receive increasing amounts of freshwater, with ecological consequences that remain poorly understood. In this study, we investigated how freshwater inputs may affect the small-scale structure of benthic food webs in a low-production high-Arctic fjord (Young Sound, NE Greenland). We seasonally sampled benthic invertebrates from two stations receiving contrasting freshwater inputs: an inner station exposed to turbid and nutrient-depleted freshwater flows and an outer station exposed to lower terrestrial influences. Benthic food web structure was described using a stable isotope approach (δ13C and δ15N), Bayesian models, and community-wide metrics. The results revealed the spatially and temporally homogeneous structure of the benthic food web, characterized by high trophic diversity (i.e., a wide community isotopic niche). Such temporal stability and spatial homogeneity mirrors the high degree of trophic plasticity and omnivory of benthic consumers that allows the maintenance of several carbon pathways through the food web despite different food availability. Furthermore, potential large inputs of shelf organic matter together with local benthic primary production (i.e., macroalgae and presumably microphytobenthos) may considerably increase the stability of the benthic food web by providing alternative food sources to locally runoff-impacted pelagic primary production. Future studies should assess beyond which threshold limit a larger increase in freshwater inputs might cancel out these stability factors and lead to marked changes in Arctic benthic ecosystems.  
  Programme 1158  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1939-5590 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 6791  
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Author Guillaume Schwob, Nicolás I. Segovia, Claudio González-Wevar, Léa Cabrol, Julieta Orlando, Elie Poulin doi  isbn
openurl 
  Title Exploring the Microdiversity Within Marine Bacterial Taxa: Toward an Integrated Biogeography in the Southern Ocean Type Journal
  Year 2021 Publication Frontiers in Microbiology Abbreviated Journal  
  Volume 12 Issue Pages 1985  
  Keywords (down)  
  Abstract Most of the microbial biogeographic patterns in the oceans have been depicted at the whole community level, leaving out finer taxonomic resolution (i.e., microdiversity) that is crucial to conduct intra-population phylogeographic study, as commonly done for macroorganisms. Here, we present a new approach to unravel the bacterial phylogeographic patterns combining community-wide survey by 16S rRNA gene metabarcoding and intra-species resolution through the oligotyping method, allowing robust estimations of genetic and phylogeographic indices, and migration parameters. As a proof-of-concept, we focused on the bacterial genus Spirochaeta across three distant biogeographic provinces of the Southern Ocean; maritime Antarctica, sub-Antarctic Islands, and Patagonia. Each targeted Spirochaeta operational taxonomic units were characterized by a substantial intrapopulation microdiversity, and significant genetic differentiation and phylogeographic structure among the three provinces. Gene flow estimations among Spirochaeta populations support the role of the Antarctic Polar Front as a biogeographic barrier to bacterial dispersal between Antarctic and sub-Antarctic provinces. Conversely, the Antarctic Circumpolar Current appears as the main driver of gene flow, connecting sub-Antarctic Islands with Patagonia and maritime Antarctica. Additionally, historical processes (drift and dispersal limitation) govern up to 86% of the spatial turnover among Spirochaeta populations. Overall, our approach bridges the gap between microbial and macrobial ecology by revealing strong congruency with macroorganisms distribution patterns at the populational level, shaped by the same oceanographic structures and ecological processes.  
  Programme 1044  
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  Series Volume Series Issue Edition  
  ISSN 1664-302X ISBN 1664-302X Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 6457  
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Author Jérémy Tornos openurl 
  Title Approches intégrées en écologie de la conservation des oiseaux marins : cas de l’utilisation d'autovaccins pour la conservation des albatros sur l'île d'Amsterdam Type Thesis
  Year 2021 Publication Abbreviated Journal  
  Volume Issue Pages  
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  Abstract L’Albatros à nez jaune de l’océan indien (Thalassarche carteri) est une espèce menacée d’extinction dont la population principale, qui se reproduit sur l’île Amsterdam (Terres Australes et Antarctiques Françaises), connait un déclin et une très forte mortalité des jeunes individus depuis plusieurs décennies. La bactérie responsable du choléra aviaire, Pasteurella multocida, est suspectée comme étant à l'origine de ces mortalités et notre équipe évalue depuis plusieurs années maintenant l'utilisation d'un vaccin pour protéger les poussins, via leur vaccination directe, mais aussi celle des femelles reproductrices susceptibles de transmettre des anticorps protecteurs à leur poussin. Le vaccin utilisé est un vaccin autologue (autovaccin) spécifiquement développé par Ceva-Biovac contre une souche de la bactérie Pasteurella multocida isolée sur cadavre d’albatros. Suite à l’obtention de premiers résultats prometteurs, les objectifs de la thèse étaient d’ajuster le protocole de vaccination, mais également de mieux appréhender et décrire les processus éco-épidémiologiques en jeu au sein des populations de vertébrés de l’île Amsterdam. Ceci a reposé sur l'analyse fine du suivi de couples reproducteurs année après année, mais aussi sur l'utilisation de données éco-épidémiologiques expérimentales complémentaires, notamment une nouvelle formulation du vaccin. Une diversité de pathogènes responsables de mortalités a pu être caractérisée. L’âge optimal de vaccination des poussins parait être vers 10 jours et la vaccination des femelles reproductrices semble pouvoir protéger les poussins pendant plusieurs années, mais la forte densité de rats (Rattus norvegicus) actifs dans les colonies a rendu difficile l’identification d’un effet protecteur fort du vaccin. Les résultats obtenus améliorent la compréhension des mécanismes de circulation d'agents infectieux chez des espèces à reproduction coloniale et permettront de comparer les bénéfices relatifs attendus de différents scénarios de vaccination. Le travail montre l’importance d’intégrer des approches complémentaires, notamment du domaine biomédical et de l’écologie des populations, pour aborder la problématique de l’émergence de maladies infectieuses dans le contexte des changements environnementaux actuels.  
  Programme 1151  
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  Notes Approved yes  
  Call Number Serial 6711  
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Author Charlène Gémard, Thierry Aubin, Eliette L. Reboud, Francesco Bonadonna doi  openurl
  Title Call rate, fundamental frequency, and syntax determine male-call attractiveness in blue petrels Halobaena caerulea Type Journal
  Year 2021 Publication Behavioral Ecology and Sociobiology Abbreviated Journal  
  Volume 75 Issue 3 Pages 55  
  Keywords (down)  
  Abstract In blue petrels (Halobaena caerulea), females are supposed to be particularly choosy and mate choice can take a couple of years. In these lifelong monogamous seabirds, choosing a good mate is crucial and has a strong influence on their fitness. Due to their nocturnal habits, the absence of sexual dimorphism, and the physical barrier between males calling from their burrow and females flying above the colony, vocal signals seem to be one of the main channels for males to communicate with potential mates. In a previous study, we investigated whether acoustic parameters of male calls carry information about morphological characteristics that might be indicators of males’ qualities. Here, we experimentally test whether these acoustic parameters linked to male characteristics are actually attractive to females. To do so, we played back modified calls of males to females in a colony of blue petrels of the Kerguelen archipelago. We found that flying females were more attracted by high-pitched calls, and by calls broadcasted at a high call rate. Previous studies showed a relationship between pitch and bill depth and length. In filter-feeding birds, such as blue petrels, bill morphology influences feeding efficiency. A high call rate is an indicator of sexual motivation and makes the caller easier to locate by potential mates and predators in the hubbub of the colony. We thus hypothesized that producing frequent high-pitched calls appeared to be preferable for a conspicuous sexual signaling although it may increase predation risks.  
  Programme 354  
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  Series Volume Series Issue Edition  
  ISSN 1432-0762 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 7055  
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Author Alison F. Banwell, Rajashree Tri Datta, Rebecca L. Dell, Mahsa Moussavi, Ludovic Brucker, Ghislain Picard, Christopher A. Shuman, Laura A. Stevens doi  openurl
  Title The 32-year record-high surface melt in 2019/2020 on the northern George VI Ice Shelf, Antarctic Peninsula Type Journal
  Year 2021 Publication The Cryosphere Abbreviated Journal  
  Volume 15 Issue 2 Pages 909-925  
  Keywords (down)  
  Abstract In the 2019/2020 austral summer, the surface melt duration and extent on the northern George VI Ice Shelf (GVIIS) was exceptional compared to the 31 previous summers of distinctly lower melt. This finding is based on analysis of near-continuous 41-year satellite microwave radiometer and scatterometer data, which are sensitive to meltwater on the ice shelf surface and in the near-surface snow. Using optical satellite imagery from Landsat 8 (2013 to 2020) and Sentinel-2 (2017 to 2020), record volumes of surface meltwater ponding were also observed on the northern GVIIS in 2019/2020, with 23 % of the surface area covered by 0.62 km3 of ponded meltwater on 19 January. These exceptional melt and surface ponding conditions in 2019/2020 were driven by sustained air temperatures ≥0 C for anomalously long periods (55 to 90 h) from late November onwards, which limited meltwater refreezing. The sustained warm periods were likely driven by warm, low-speed (≤7.5 m s−1) northwesterly and northeasterly winds and not by foehn wind conditions, which were only present for 9 h total in the 2019/2020 melt season. Increased surface ponding on ice shelves may threaten their stability through increased potential for hydrofracture initiation; a risk that may increase due to firn air content depletion in response to near-surface melting.

 
  Programme 1110  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1994-0416 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 7654  
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Author Dedieu, J.-P., A. Wendleder, B. Cerino, J. Boike, E. Bernard, J.-C. Gallet, and H.-W. Jacobi doi  openurl
  Title Snow change detection from polarimetric SAR time-series at X-band (Svalbard, Norway), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-149. Type Peer-reviewed symposium
  Year 2021 Publication Egusphere Abbreviated Journal  
  Volume Issue Pages  
  Keywords (down)  
  Abstract

Due to recent climate change conditions, i.e. increasing temperatures and changing precipitation patterns, arctic snow cover dynamics exhibit strong changes in terms of extent and duration. Arctic amplification processes and impacts are well documented expected to strengthen in coming decades. In this context, innovative observation methods are helpful for a better comprehension of the spatial variability of snow properties relevant for climate research and hydrological applications.

Microwave remote sensing provides exceptional spatial and temporal performance in terms of all-weather application and target penetration. Time-series of Synthetic Active Radar images (SAR) are becoming more accessible at different frequencies and polarimetry has demonstrated a significant advantage for detecting changes in different media. Concerning arctic snow monitoring, SAR sensors can offer continuous time-series during the polar night and with cloud cover, providing a consequent advantage in regard of optical sensors.

The aim of this study is dedicated to the spatial/temporal variability of snow in the Ny-Ålesund area on the Br∅gger peninsula, Svalbard (N 78°55’ / E 11° 55’). The TerraSAR-X satellite (DLR, Germany) operated at X-band (3.1 cm, 9.6 GHz) with dual co-pol mode (HH/VV) at 5-m spatial resolution, and with high incidence angles (36° to 39°) poviding a better snow penetration and reducing topographic constraints. A dataset of 92 images (ascending and descending) is available since 2017, together with a high resolution DEM (NPI 5-m) and consistent in-situ measurements of meteorological data and snow profiles including glaciers sites.

Polarimetric processing is based on the Kennaugh matrix decomposition, copolar phase coherence (CCOH) and copolar phase difference (CPD). The Kennaugh matrix elements K0, K3, K4, and K7 are, respectively, the total intensity, phase ratio, intensity ratio, and shift between HH and VV phase center. Their interpretation allows analysing the structure of the snowpack linked to the near real time of in-situ measurements (snow profiles).

The X-band signal is strongly influenced by the snow stratigraphy: internal ice layers reduce or block the penetration of the signal into the snow pack. The best R2 correlation performances between estimated and measured snow heights are ranging from 0.50 to 0.70 for dry snow conditions. Therefore, the use of the X-band for regular snow height estimations remains limited under these conditions.

Conversely, this study shows the benefit of TerraSAR-X thanks to the Kennaugh matrix elements analysis. A focus is set on the Copolar Phase Difference (CPD, Leinss 2016) between VV and HH polarization: Φ CPD = Φ VV – Φ HH. Our results indicate that the CPD values are related to the snow metamorphism: positive values correspond to dry snow (horizontal structures), negative values indicate recrystallization processes (vertical structures).

Backscattering evolution in time offer a good proxy for meteorological events detection, impacting on snow metamorphism. Fresh snowfalls or melting processes can then be retrieved at the regional scale and linked to air temperature or precipitation measurements at local scale. Polarimetric SAR time series is therefore of interest to complement satellite-based precipitation measurements in the Arctic.

 
  Programme 1126  
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  Series Volume Series Issue Edition  
  ISSN EGU21-149 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 7247  
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Author W. J. Sydeman, D. S. Schoeman, S. A. Thompson, B. A. Hoover, M. García-Reyes, F. Daunt, P. Agnew, T. Anker-Nilssen, C. Barbraud, R. Barrett, P. H. Becker, E. Bell, P. D. Boersma, S. Bouwhuis, B. Cannell, R. J. M. Crawford, P. Dann, K. Delord, G. Elliott, K. E. Erikstad, E. Flint, R. W. Furness, M. P. Harris, S. Hatch, K. Hilwig, J. T. Hinke, J. Jahncke, J. A. Mills, T. K. Reiertsen, H. Renner, R. B. Sherley, C. Surman, G. Taylor, J. A. Thayer, P. N. Trathan, E. Velarde, K. Walker, S. Wanless, P. Warzybok, Y. Watanuki doi  openurl
  Title Hemispheric asymmetry in ocean change and the productivity of ecosystem sentinels Type Journal
  Year 2021 Publication Science Abbreviated Journal  
  Volume 372 Issue 6545 Pages 980-983  
  Keywords (down)  
  Abstract Sampling seabirds The vastness of the worlds' oceans makes them difficult to monitor. Seabirds that forage and breed across oceans globally have been recognized as sentinels of ocean health. Sydeman et al. looked across seabird species of both the Northern and Southern Hemispheres and found varying patterns. Northern Hemisphere species exhibited greater signs of stress and reduced breeding success, indicative of low fish resources. Southern Hemisphere species showed less impact on reproductive output, suggesting that the fish populations there have thus far been less disturbed. The differences across hemispheres indicate different strategies for conservation, with active recovery needed in the north and enhanced protection in the south. Science, abf1772, this issue p. 980 Climate change and other human activities are causing profound effects on marine ecosystem productivity. We show that the breeding success of seabirds is tracking hemispheric differences in ocean warming and human impacts, with the strongest effects on fish-eating, surface-foraging species in the north. Hemispheric asymmetry suggests the need for ocean management at hemispheric scales. For the north, tactical, climate-based recovery plans for forage fish resources are needed to recover seabird breeding productivity. In the south, lower-magnitude change in seabird productivity presents opportunities for strategic management approaches such as large marine protected areas to sustain food webs and maintain predator productivity. Global monitoring of seabird productivity enables the detection of ecosystem change in remote regions and contributes to our understanding of marine climate impacts on ecosystems. The breeding success of seabirds is tracking hemispheric differences in ocean warming and human impacts. The breeding success of seabirds is tracking hemispheric differences in ocean warming and human impacts.  
  Programme 109  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0036-8075, 1095-9203 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 7980  
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