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2021 |
Publication |
Atmospheric Chemistry and Physics |
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Volume |
21 |
Issue |
4 |
Pages |
3035-3057 |
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1192 |
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1680-7316 |
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yes |
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8604 |
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Author |
Jun Xie, Risheng Chu, Sidao Ni |
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Title |
Evaluating Global Tomography Models With Antipodal Ambient Noise Cross-Correlation Functions |
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Journal |
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Year |
2021 |
Publication |
Journal of Geophysical Research: Solid Earth |
Abbreviated Journal |
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Volume |
126 |
Issue |
3 |
Pages |
e2020JB020444 |
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Keywords |
ambient noise cross-correlation functions antipodal surface waves mantle heterogeneity tomography model evaluation |
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133 |
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2169-9356 |
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yes |
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Serial |
7993 |
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Author |
Pierre-Yves Pascal, Yann Reynaud, Elie Poulin, Chantal De Ridder, Thomas Saucede |
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Title |
Feeding in spatangoids: the case of Abatus Cordatus in the Kerguelen Islands (Southern Ocean) |
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Year |
2021 |
Publication |
Polar Biology |
Abbreviated Journal |
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Volume |
44 |
Issue |
4 |
Pages |
795-808 |
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Abstract |
Irregular urchins exclusively live in marine soft bottom habitats, dwelling either upon or inside sediments and selectively picking up sediment grains and organic particles, or swallowing bulk sediment to feed on the associated organic matter. The exact food source and dietary requirements of most irregular echinoids, however, remain incompletely understood. The schizasterid species Abatus cordatus (Verrill, 1876) is a sub-Antarctic spatangoid that is endemic to the Kerguelen. The feeding behaviour of A. cordatus was investigated using simultaneously metabarcoding and stable isotope approaches. Comparison of ingested and surrounding sediments by metabarcoding revealed a limited selective ingestion of prokaryotes and eukaryotes by the urchin. Compared to surrounding sediments, the gut content had (i) higher carbon and nitrogen concentrations potentially due to selective ingestion of organic matter and/or the sea urchin mucus secretion and (ii) ?15N enrichment due to the selective assimilation of lighter isotope in the gut. Feeding experiments were performed using 13C and 15 N-enriched sediments in aquariums. The progression of stable isotope enrichment in proximal and distal parts of the digestive track of A. cordatus revealed that all particles are not similarly transported likely due to siphon functioning. Ingestion of water with associated dissolved and particulate organic matter should play an important role in urchin nutrition. A. cordatus had a gut resident time fluctuating between 76 and 101 h and an ingestion rate of 36 mg dry sediment h?1 suggesting that dense populations of the species may play a key ecological role through bioturbation in soft bottom shallow-water habitats of the Kerguelen Islands. |
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1044 |
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ISSN |
1432-2056 |
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yes |
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Call Number |
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Serial |
8000 |
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Title |
Huff and puff and blow down: invasive plants traits response to strong winds at the Southern Oceanic Islands |
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Journal |
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Year |
2021 |
Publication |
Oikos |
Abbreviated Journal |
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Volume |
130 |
Issue |
11 |
Pages |
1919-1929 |
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Keywords |
environmental filter functional traits hypervolume Iles Kerguelen intraspecific variability mechanical stress |
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Abstract |
Invasions constitute a major driver of biodiversity changes. Insular plant communities are particularly vulnerable to invasions and are relevant models for investigating mechanisms supporting the establishment and spread of introduced plants. Terrestrial flora of sub-Antarctic islands must often thrive in highly windy habitats, thus imposing strong mechanical constraints on individuals. Many alien plants at the sub-Antarctic islands are of tropical or temperate origins, where they were exposed to less stringent wind conditions. As wind likely represents a strong environmental filter for the successful establishment and further geographic spread of plants, they should have developed responses to resist and successfully colonize the Iles Kerguelen. We studied responses to wind of three herbaceous species that are invasive at Iles Kerguelen. We sampled plant individuals at different locations, under windy and sheltered conditions. Traits related to wind avoidance and tolerance and to resource acquisition were measured. We additionally assessed individual performance (biomass) to determine the consequences of trait variations. We focused on trait mean and variance, in particular, through the calculation of hypervolumes. This study emphasized that wind has important effects on plant economics spectrum, including traits involved in mechanical avoidance and light acquisition, with varying strategies, which seem to depend on the biological type of the species (grass versus non-grass). Wind generally reduces individual performance, and this negative effect is not direct but operates through the modification of plant trait values. Furthermore, analyses performed at the hypervolume scale indicate that not only functional trait mean but also its variability account for plant performance. The existence of contrasting growth strategies to cope with local environmental conditions suggests that invaders will be able to occupy different niches, which may ultimately impact local communities. Our results highlight the importance of considering multi-traits responses to meaningfully capture plant adjustments to stress. |
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136 |
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ISSN |
1600-0706 |
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yes |
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Call Number |
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Serial |
8372 |
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Author |
Fabrice Genevois, Christophe Barbraud |
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Year |
2021 |
Publication |
Polar Biology |
Abbreviated Journal |
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Volume |
44 |
Issue |
1 |
Pages |
217-219 |
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Keywords |
Antarctic Interspecific feeding Penguin |
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Abstract |
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Programme |
109 |
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ISSN |
1432-2056 |
ISBN |
1432-2056 |
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yes |
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Call Number |
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Serial |
8324 |
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Author |
Samara Danel, Jules Chiffard-Carricaburu, Francesco Bonadonna, Anna P. Nesterova |
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Title |
Exclusion in the field: wild brown skuas find hidden food in the absence of visual information |
Type |
Journal |
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Year |
2021 |
Publication |
Animal Cognition |
Abbreviated Journal |
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Volume |
24 |
Issue |
4 |
Pages |
867-876 |
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Programme |
354 |
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ISSN |
1435-9456 |
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yes |
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Call Number |
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Serial |
7947 |
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Author |
Alain Manceau, Anne-Claire Gaillot, Pieter Glatzel, Yves Cherel, Paco Bustamante |
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Journal |
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Year |
2021 |
Publication |
Environmental Science & Technology |
Abbreviated Journal |
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Volume |
55 |
Issue |
3 |
Pages |
1515-1526 |
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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. |
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Programme |
109 |
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ISSN |
0013-936X |
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yes |
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Call Number |
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Serial |
7942 |
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Title |
Echo occurrence in the southern polar ionosphere for the SuperDARN Dome C East and Dome C North radars |
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Journal |
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Year |
2021 |
Publication |
Polar Science |
Abbreviated Journal |
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Volume |
28 |
Issue |
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Pages |
100684 |
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Keywords |
Echo occurrence IRI model Polar cap radars Ray-tracing |
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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. |
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312 |
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ISSN |
1873-9652 |
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yes |
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Call Number |
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Serial |
8020 |
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Title |
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) |
Type |
Journal |
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Year |
2021 |
Publication |
Science of The Total Environment |
Abbreviated Journal |
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Volume |
770 |
Issue |
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Pages |
145252 |
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Keywords |
Bacterial viability EPS isomerase Micro- and macro-zooplankton Salinity stress Sea ice algae |
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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. |
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1164 |
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ISSN |
0048-9697 |
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yes |
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Serial |
8253 |
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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 |
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Title |
The 32-year record-high surface melt in 2019/2020 on the northern George VI Ice Shelf, Antarctic Peninsula |
Type |
Journal |
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Year |
2021 |
Publication |
The Cryosphere |
Abbreviated Journal |
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Volume |
15 |
Issue |
2 |
Pages |
909-925 |
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Keywords |
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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. |
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1110 |
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ISSN |
1994-0416 |
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yes |
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Call Number |
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Serial |
7654 |
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