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2021 |
Publication |
Remote Sensing |
Abbreviated Journal |
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Volume |
13 |
Issue |
10 |
Pages |
1978 |
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Keywords |
arctic cryosphere moraine photogrammetry snow water equivalent snowcover spatial dynamics UAV-SfM |
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Abstract |
The global climate shift currently underway has significant impacts on both the quality and quantity of snow precipitation. This directly influences the spatial variability of the snowpack as well as cumulative snow height. Contemporary glacier retreat reorganizes periglacial morphology: while the glacier area decreases, the moraine area increases. The latter is becoming a new water storage potential that is almost as important as the glacier itself, but with considerably more complex topography. Hence, this work fills one of the missing variables of the hydrological budget equation of an arctic glacier basin by providing an estimate of the snow water equivalent (SWE) of the moraine contribution. Such a result is achieved by investigating Structure from Motion (SfM) image processing that is applied to pictures collected from an Unmanned Aerial Vehicle (UAV) as a method for producing snow depth maps over the proglacial moraine area. Several UAV campaigns were carried out on a small glacial basin in Spitsbergen (Arctic): the measurements were made at the maximum snow accumulation season (late April), while the reference topography maps were acquired at the end of the hydrological year (late September) when the moraine is mostly free of snow. The snow depth is determined from Digital Surface Model (DSM) subtraction. Utilizing dedicated and natural ground control points for relative positioning of the DSMs, the relative DSM georeferencing with sub-meter accuracy removes the main source of uncertainty when assessing snow depth. For areas where snow is deposited on bare rock surfaces, the correlation between avalanche probe in-situ snow depth measurements and DSM differences is excellent. Differences in ice covered areas between the two measurement techniques are attributed to the different quantities measured: while the former only measures snow accumulation, the latter includes all of the ice accumulation during winter through which the probe cannot penetrate, in addition to the snow cover. When such inconsistencies are observed, icing thicknesses are the source of the discrepancy that is observed between avalanche probe snow cover depth measurements and differences of DSMs. |
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1108 |
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yes |
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4442 |
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Title |
Exploring the Microdiversity Within Marine Bacterial Taxa: Toward an Integrated Biogeography in the Southern Ocean |
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Year |
2021 |
Publication |
Frontiers in Microbiology |
Abbreviated Journal |
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Volume |
12 |
Issue |
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Pages |
1985 |
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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. |
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1044 |
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1664-302X |
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1664-302X |
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yes |
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6457 |
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Author |
Damien Ertz, Neil Sanderson, Marc Lebouvier |
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Title |
Thelopsis challenges the generic circumscription in the Gyalectaceae and brings new insights to the taxonomy of Ramonia |
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Year |
2021 |
Publication |
The Lichenologist |
Abbreviated Journal |
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Volume |
53 |
Issue |
1 |
Pages |
45-61 |
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Keywords |
Arthoniales Gyalectales lichen multispory phylogeny |
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Abstract |
The genus Thelopsis was classified in the family Stictidaceae but its systematic position has never been investigated by molecular methods. In order to determine its family placement and to test its monophyly, fungal DNA of recent collections of Thelopsis specimens was sequenced. Phylogenetic analyses using nuLSU, RPB2 and mtSSU sequences reveal that members of Thelopsis form a monophyletic group within the genus Gyalecta as currently accepted. The placement of Thelopsis, including the generic type T. rubella, within the genus Gyalecta challenges the generic circumscription of this group because Thelopsis is well recognized by the combination of morphological characters: perithecioid ascomata, well-developed periphysoids, polysporous asci and small, few-septate ellipsoid-oblong ascospores. The sterile sorediate Opegrapha corticola is also placed in the Gyalectaceae as sister species to Thelopsis byssoidea + T. rubella. Ascomata of O. corticola are illustrated for the first time and support its placement in the genus Thelopsis. The hypothesis that O. corticola might represent the sorediate fertile morph of T. rubella is not confirmed because the species is phylogenetically and morphologically distinct. Thelopsis is recovered as polyphyletic, with T. melathelia being placed as sister species to Ramonia. The new combinations Thelopsis corticola (Coppins & P. James) Sanderson & Ertz comb. nov. and Ramonia melathelia (Nyl.) Ertz comb. nov. are introduced and a new species of Gyalecta, G. amsterdamensis Ertz, is described from Amsterdam and Saint-Paul Islands, characterized by a sterile thallus with discrete soralia. Petractis luetkemuelleri and P. nodispora are accommodated in the new genus Neopetractis, differing from the generic type (P. clausa) by having a different phylogenetic position and a different photobiont. Francisrosea bicolor Ertz & Sanderson gen. & sp. nov. is described for a sterile sorediate lichen somewhat similar to Opegrapha corticola but having an isolated phylogenetic position as sister to a clade including Gyalidea praetermissa and the genera Neopetractis and Ramonia. Gyalecta farlowii, G. nidarosiensis and G. carneola are placed in a molecular phylogeny for the first time. The taxonomic significance of morphological characters in Gyalectaceae is discussed. |
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1167 |
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0024-2829, 1096-1135 |
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yes |
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Call Number |
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Serial |
7078 |
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Title |
Call rate, fundamental frequency, and syntax determine male-call attractiveness in blue petrels Halobaena caerulea |
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Year |
2021 |
Publication |
Behavioral Ecology and Sociobiology |
Abbreviated Journal |
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Volume |
75 |
Issue |
3 |
Pages |
55 |
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Abstract |
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Programme |
354 |
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ISSN |
1432-0762 |
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yes |
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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 |
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Title |
The 32-year record-high surface melt in 2019/2020 on the northern George VI Ice Shelf, Antarctic Peninsula |
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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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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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Serial |
7654 |
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Title |
Hemispheric asymmetry in ocean change and the productivity of ecosystem sentinels |
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Year |
2021 |
Publication |
Science |
Abbreviated Journal |
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Volume |
372 |
Issue |
6545 |
Pages |
980-983 |
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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. |
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Programme |
109 |
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ISSN |
0036-8075, 1095-9203 |
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yes |
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7980 |
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Author |
Alexandra Lavrillier, Semen Gabyshev, Liudmila Egorova, Galina Makarova, Maia Lomovtseva-Adukanova |
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Title |
Analysing Non-Existent and Existing Tourisms in Eastern Siberia among the Evenki, Even, Koryak and Itelmen |
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2021 |
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Issue |
2020/3-2021/1 |
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Programme |
1127 |
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ISSN |
0755-7809 |
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yes |
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Serial |
6582 |
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Author |
Steven Franke, Daniela Jansen, Sebastian Beyer, Niklas Neckel, Tobias Binder, John Paden, Olaf Eisen |
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Title |
Complex Basal Conditions and Their Influence on Ice Flow at the Onset of the Northeast Greenland Ice Stream |
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Journal |
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Year |
2021 |
Publication |
Journal of Geophysical Research: Earth Surface |
Abbreviated Journal |
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Volume |
126 |
Issue |
3 |
Pages |
e2020JF005689 |
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Keywords |
basal roughness bed conditions Greenland Ice Sheet ice stream Northeast Greenland Ice Stream radio-echo sounding |
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Abstract |
Abstract The ice stream geometry and large ice surface velocities at the onset region of the Northeast Greenland Ice Stream (NEGIS) are not yet well reproduced by ice sheet models. The quantification of basal sliding and a parametrization of basal conditions remains a major gap. In this study, we assess the basal conditions of the onset region of the NEGIS in a systematic analysis of airborne ultra-wideband radar data. We evaluate basal roughness and basal return echoes in the context of the current ice stream geometry and ice surface velocity. We observe a change from a smooth to a rougher bed where the ice stream widens, and a distinct roughness anisotropy, indicating a preferred orientation of subglacial structures. In the upstream region, the excess ice mass flux through the shear margins is evacuated by ice flow acceleration and along-flow stretching of the ice. At the downstream part, the generally rougher bed topography correlates with a decrease in flow acceleration and lateral variations in ice surface velocity. Together with basal water routing pathways, this hints to two different zones in this part of the NEGIS: the upstream region collecting water, with a reduced basal traction, and downstream, where the ice stream is slowing down and is widening on a rougher bed, with a distribution of basal water toward the shear margins. Our findings support the hypothesis that the NEGIS is strongly interconnected to the subglacial water system in its onset region, but also to the subglacial substrate and morphology. |
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Programme |
1180 |
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ISSN |
2169-9003 |
ISBN |
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Approved |
yes |
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Serial |
7272 |
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Title |
Behavioural responses of breeding arctic sandpipers to ground-surface temperature and primary productivity |
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Journal |
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Year |
2021 |
Publication |
Science of The Total Environment |
Abbreviated Journal |
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Volume |
755 |
Issue |
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Pages |
142485 |
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Keywords |
Environmental conditions Incubation behaviour Incubation recesses Incubation strategy Lag effects NDVI Shorebird |
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Abstract |
Most birds incubate their eggs, which requires time and energy at the expense of other activities. Birds generally have two incubation strategies: biparental where both mates cooperate in incubating eggs, and uniparental where a single parent incubates. In harsh and unpredictable environments, incubation is challenging due to high energetic demands and variable resource availability. We studied the relationships between the incubation behaviour of sandpipers (genus Calidris) and two environmental variables: temperature and a proxy of primary productivity (i.e. NDVI). We investigated how these relationships vary between incubation strategies and across species among strategies. We also studied how the relationship between current temperature and incubation behaviour varies with previous day's temperature. We monitored the incubation behaviour of nine sandpiper species using thermologgers at 15 arctic sites between 2016 and 2019. We also used thermologgers to record the ground surface temperature at conspecific nest sites and extracted NDVI values from a remote sensing product. We found no relationship between either environmental variables and biparental incubation behaviour. Conversely, as ground-surface temperature increased, uniparental species decreased total duration of recesses (TDR) and mean duration of recesses (MDR), but increased number of recesses (NR). Moreover, small species showed stronger relationships with ground-surface temperature than large species. When all uniparental species were combined, an increase in NDVI was correlated with higher mean duration, total duration and number of recesses, but relationships varied widely across species. Finally, some uniparental species showed a lag effect with a higher nest attentiveness after a warm day while more recesses occurred after a cold day than was predicted based on current temperatures. We demonstrate the complex interplay between shorebird incubation strategies, incubation behaviour, and environmental conditions. Understanding how species respond to changes in their environment during incubation helps predict their future reproductive success. |
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1036 |
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ISSN |
0048-9697 |
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yes |
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Call Number |
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Serial |
7553 |
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Title |
Meeting Paris agreement objectives will temper seabird winter distribution shifts in the North Atlantic Ocean |
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Journal |
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Year |
2021 |
Publication |
Global Change Biology |
Abbreviated Journal |
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Volume |
27 |
Issue |
7 |
Pages |
1457-1469 |
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Programme |
330, 388 |
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Bachelor's thesis |
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ISSN |
1365-2486 |
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Approved |
yes |
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Call Number |
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Serial |
7987 |
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