. (2021). Fine-scale spatial segregation in a pelagic seabird driven by differential use of tidewater glacier fronts (Vol. 11).
Abstract: In colonially breeding marine predators, individual movements and colonial segregation are influenced by seascape characteristics. Tidewater glacier fronts are important features of the Arctic seascape and are often described as foraging hotspots. Albeit their documented importance for wildlife, little is known about their structuring effect on Arctic predator movements and space use. In this study, we tested the hypothesis that tidewater glacier fronts can influence marine bird foraging patterns and drive spatial segregation among adjacent colonies. We analysed movements of black-legged kittiwakes (Rissa tridactyla) in a glacial fjord by tracking breeding individuals from five colonies. Although breeding kittiwakes were observed to travel up to ca. 280 km from the colony, individuals were more likely to use glacier fronts located closer to their colony and rarely used glacier fronts located farther away than 18 km. Such variation in the use of glacier fronts created fine-scale spatial segregation among the four closest (ca. 7 km distance on average) kittiwake colonies. Overall, our results support the hypothesis that spatially predictable foraging patches like glacier fronts can have strong structuring effects on predator movements and can modulate the magnitude of intercolonial spatial segregation in central-place foragers.
Keywords: Behavioural ecology Biogeography
Programme: 330
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. (2021). Evaluation of candidate models for the 13th generation International Geomagnetic Reference Field (Vol. 73).
Keywords: Geomagnetism IGRF Magnetic field modeling
Programme: 139
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. (2021). International Geomagnetic Reference Field: the thirteenth generation (Vol. 73).
Abstract: In December 2019, the International Association of Geomagnetism and Aeronomy (IAGA) Division V Working Group (V-MOD) adopted the thirteenth generation of the International Geomagnetic Reference Field (IGRF). This IGRF updates the previous generation with a definitive main field model for epoch 2015.0, a main field model for epoch 2020.0, and a predictive linear secular variation for 2020.0 to 2025.0. This letter provides the equations defining the IGRF, the spherical harmonic coefficients for this thirteenth generation model, maps of magnetic declination, inclination and total field intensity for the epoch 2020.0, and maps of their predicted rate of change for the 2020.0 to 2025.0 time period.
Keywords: Geomagnetism IGRF Magnetic field modeling
Programme: 139
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. (2021). Exploring the interplay between nest vocalizations and foraging behaviour in breeding birds (Vol. 180).
Keywords: bird communication foraging behaviour reproductive partner vocalization
Programme: 1091
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Alison F. Banwell, Rajashree Tri Datta, Rebecca L. Dell, Mahsa Moussavi, Ludovic Brucker, Ghislain Picard, Christopher A. Shuman, Laura A. Stevens. (2021). The 32-year record-high surface melt in 2019/2020 on the northern George VI Ice Shelf, Antarctic Peninsula (Vol. 15).
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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. (2021). Viability and stress state of bacteria associated with primary production or zooplankton-derived suspended particulate matter in summer along a transect in Baffin Bay (Arctic Ocean) (Vol. 770).
Abstract: In the framework of the GreenEdge Project (whose the general objective is to understand the dynamic of the phytoplankton spring bloom in Arctic Ocean), lipid composition and viability and stress state of bacteria were monitored in sea ice and suspended particulate matter (SPM) samples collected in 2016 along a transect from sea ice to open water in Baffin Bay (Arctic Ocean). Lipid analyses confirmed the dominance of diatoms in the bottommost layer of ice and suggested (i) the presence of a strong proportion of micro-zooplankton in SPM samples collected at the western ice covered St 403 and St 409 and (ii) a high proportion of macro-zooplankton (copepods) in SPM samples collected at the eastern ice covered St 413 and open water St 418. The use of the propidium monoazide (PMA) method allowed to show a high bacterial mortality in sea ice and in SPM material collected in shallower waters at St 409 and St 418. This mortality was attributed to the release of bactericidal free fatty acids by sympagic diatoms under the effect of light stress. A strong cis-trans isomerization of bacterial MUFAs was observed in the deeper SPM samples collected at the St 403 and St 409. It was attributed to the ingestion of bacteria stressed by salinity in brine channels of ice by sympagic bacterivorous microzooplankton (ciliates) incorporating trans fatty acids of their preys before to be released in the water column during melting. The high trans/cis ratios also observed in SPM samples collected in the shallower waters at St 413 and St 418 suggest the presence of positively or neutrally buoyant extracellular polymeric substances (EPS)-rich particles retained in sea ice and discharged (with bacteria stressed by salinity) in seawater after the initial release of algal biomass. Such EPS particles, which are generally considered as ideal vectors for bacterial horizontal distribution in the Arctic, appeared to contain a high proportion of dead and non-growing bacteria.
Keywords: Bacterial viability EPS isomerase Micro- and macro-zooplankton Salinity stress Sea ice algae
Programme: 1164
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. (2021). Echo occurrence in the southern polar ionosphere for the SuperDARN Dome C East and Dome C North radars (Vol. 28).
Abstract: In this paper, echo occurrence rates for the Dome C East (DCE) and the new Dome C North (DCN) radars are studied. We report the ionospheric and ground scatter echo occurrence rates for selected periods around equinoxes and solstices in the final part of the solar cycle XXIV. The occurrence maps built in Altitude Adjusted Corrected Geomagnetic latitude and Magnetic Local Time coordinates show peculiar patterns highly variable with season. The comparisons of the radar observations with the International Reference Ionosphere model electron density and with ray tracing simulations allow us to explain the major features of observed patterns in terms of electron density variations. The study shows the great potential of the DCE and DCN radar combination to the Super Dual Auroral Radar Network (SuperDARN) convection mapping in terms of monitoring key regions of the high-latitude ionosphere critical for understanding of the magnetospheric dynamics.
Keywords: Echo occurrence IRI model Polar cap radars Ray-tracing
Programme: 312
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Alain Manceau, Anne-Claire Gaillot, Pieter Glatzel, Yves Cherel, Paco Bustamante. (2021). (Vol. 55).
Abstract: In vivo and in vitro evidence for detoxification of methylmercury (MeHg) as insoluble mercury selenide (HgSe) underlies the central paradigm that mercury exposure is not or little hazardous when tissue Se is in molar excess (Se:Hg > 1). However, this hypothesis overlooks the binding of Hg to selenoproteins, which lowers the amount of bioavailable Se that acts as a detoxification reservoir for MeHg, thereby underestimating the toxicity of mercury. This question was addressed by determining the chemical forms of Hg in various tissues of giant petrels Macronectes spp. using a combination of high energy-resolution X-ray absorption near edge structure and extended X-ray absorption fine structure spectroscopy, and transmission electron microscopy coupled to elemental mapping. Three main Hg species were identified, a MeHg-cysteinate complex, a four-coordinate selenocysteinate complex (Hg(Sec)4), and a HgSe precipitate, together with a minor dicysteinate complex Hg(Cys)2. The amount of HgSe decreases in the order liver > kidneys > brain = muscle, and the amount of Hg(Sec)4 in the order muscle > kidneys > brain > liver. On the basis of biochemical considerations and structural modeling, we hypothesize that Hg(Sec)4 is bound to the carboxy-terminus domain of selenoprotein P (SelP) which contains 12 Sec residues. Structural flexibility allows SelP to form multinuclear Hgx(Se,Sec)y complexes, which can be biomineralized to HgSe by protein self-assembly. Because Hg(Sec)4 has a Se:Hg molar ratio of 4:1, this species severely depletes the stock of bioavailable Se for selenoprotein synthesis and activity to one ?g Se/g dry wet in the muscle of several birds. This concentration is still relatively high because selenium is naturally abundant in seawater, therefore it probably does not fall below the metabolic need for essential selenium. However, this study shows that this may not be the case for terrestrial animals, and that muscle may be the first tissue potentially injured by Hg toxicity.
Programme: 109
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Samara Danel, Jules Chiffard-Carricaburu, Francesco Bonadonna, Anna P. Nesterova. (2021). Exclusion in the field: wild brown skuas find hidden food in the absence of visual information (Vol. 24).
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Fabrice Genevois, Christophe Barbraud. (2021). (Vol. 44).
Keywords: Antarctic Interspecific feeding Penguin
Programme: 109
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