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Author |
Camille Moreau, Quentin Jossart, Bruno Danis, Marc Eléaume, Henrik Christiansen, Charlène Guillaumot, Rachel Downey, Thomas Saucède |
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Title |
The high diversity of Southern Ocean sea stars (Asteroidea) reveals original evolutionary pathways |
Type |
Journal |
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Year |
2021 |
Publication |
Progress in oceanography |
Abbreviated Journal |
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Volume |
190 |
Issue |
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Pages |
102472 |
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Keywords  |
Antarctica Biodiversity COI mtDNA Echinodermata Evolution Phylogeography |
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Abstract |
Benthic life in the Southern Ocean (SO) features unique life history traits and species assemblages, but the origin and evolution of many of these taxonomic groups is still unclear. Sea stars (Asteroidea) are a diversified and abundant component of benthic ecosystems in the SO, in which they can play key ecological roles. Former studies suggest that the diversity of the entire class is still poorly known and underestimated, hampering the assessment of the origin and evolution of the class in the SO. In the present study, we analyse spatial patterns of SO sea star diversity using an occurrence database of ~14,000 entries. The biogeographic analysis is coupled with the exploration of an extensive molecular phylogeny based on over 4,400 specimen sequences to inform, support and/or question the observed diversity patterns. We show that the current taxonomy of SO asteroids needs revision and that their diversity has generally been overlooked and misinterpreted. Molecular results highlight the recent diversification of most studied taxa, at genus and species levels, which supports an evolutionary scenario referring to successive invasion and exchange events between the SO and adjacent regions, and clade diversification during periods of rapid environmental changes driven by the succession of glacial cycles. Our work advocates for employing, and endorsing the use of extensive genetic barcode libraries for biodiversity studies. |
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1044,1124 |
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Bachelor's thesis |
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0079-6611 |
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yes |
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Serial |
8183 |
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Author |
R. Olmi, M. Bittelli, G. Picard, L. Arnaud, A. Mialon, S. Priori |
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Title |
Investigating the influence of the grain size and distribution on the macroscopic dielectric properties of Antarctic firn |
Type |
Journal |
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Year |
2021 |
Publication |
Cold Regions Science and Technology |
Abbreviated Journal |
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Volume |
185 |
Issue |
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Pages |
103254 |
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Keywords |
Antarctica Close−off Dielectric measurements Dielectric model Firn Full wave EM simulations Ice cores |
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Abstract |
This study is based on the analysis of detailed measurements of firn dielectric properties performed in Antarctica through coring down to 106 m. Dielectric measurements in the frequency band (0.4–2.5 GHz) have been carried out using an open−resonator probe. Density was also measured for the same samples. The experimental results confirmed the well−known dependence of the real part of permittivity ε′ on depth and density, showing an increase of ε′ with density. The imaginary part also increases with depth with a rather complex dependence on frequency, probably due to the presence of salts or impurities. The analysis of the experimental data was performed by implementing 3D and 2D full wave numerical models, to simulate a mixture of firn crystals at prescribed densities, corresponding to the measured densities on the ice cores. The numerical analysis of the ensemble of inclusions showed that the usual symmetric formulae used for modeling ice dielectric properties agree with the average results of the simulation, but they are not able to explain the spreading of the measured data at given density. A dielectric model was then developed allowing for quantification of the dependence of dielectric properties on density, by combining two models: one consisting in firn crystals into an air host, the other assuming the presence of air inclusions into a homogeneous firn host. The weighted equation is based on the volume fraction. A simple geometric shape (ellipsoidal) is assumed for both ice crystals and air inclusions. This kind of shape is reasonable for the purpose of the dielectric study. The result is a mixture, smoothly changing from firn particles in air (low density) to air bubbles in an ice matrix (high density). A statistical analysis has been accomplished to investigate the dependence of the dielectric properties on the geometrical arrangement of the inclusions. For that purpose, a large number of simulations with different arrangements (micro−states) giving rise to the same average density (macro−states) has been carried out. The permittivity change due to micro−state variability appears to be at least two−three times the model variation due to density alone, and comparable to the measured variability at a given depth, suggesting that firn structure has a significant effect on the dielectric properties. |
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1110 |
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ISSN |
0165-232X |
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yes |
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Serial |
7995 |
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Author |
Andrés Barbosa, Arvind Varsani, Virginia Morandini, Wray Grimaldi, Ralph E. T. Vanstreels, Julia I. Diaz, Thierry Boulinier, Meagan Dewar, Daniel González-Acuña, Rachael Gray, Clive R. McMahon, Gary Miller, Michelle Power, Amandine Gamble, Michelle Wille |
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Title |
Risk assessment of SARS-CoV-2 in Antarctic wildlife |
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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 |
143352 |
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Keywords |
Antarctica Coronavirus COVID-19 Mitigation measures Reverse zoonoses Transmission |
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Abstract |
The coronavirus disease 2019 (COVID-19) pandemic is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This pathogen has spread rapidly across the world, causing high numbers of deaths and significant social and economic impacts. SARS-CoV-2 is a novel coronavirus with a suggested zoonotic origin with the potential for cross-species transmission among animals. Antarctica can be considered the only continent free of SARS-CoV-2. Therefore, concerns have been expressed regarding the potential human introduction of this virus to the continent through the activities of research or tourism to minimise the effects on human health, and the potential for virus transmission to Antarctic wildlife. We assess the reverse-zoonotic transmission risk to Antarctic wildlife by considering the available information on host susceptibility, dynamics of the infection in humans, and contact interactions between humans and Antarctic wildlife. The environmental conditions in Antarctica seem to be favourable for the virus stability. Indoor spaces such as those at research stations, research vessels or tourist cruise ships could allow for more transmission among humans and depending on their movements between different locations the virus could be spread across the continent. Among Antarctic wildlife previous in silico analyses suggested that cetaceans are at greater risk of infection whereas seals and birds appear to be at a low infection risk. However, caution needed until further research is carried out and consequently, the precautionary principle should be applied. Field researchers handling animals are identified as the human group posing the highest risk of transmission to animals while tourists and other personnel pose a significant risk only when in close proximity (< 5 m) to Antarctic fauna. We highlight measures to reduce the risk as well as identify of knowledge gaps related to this issue. |
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1151 |
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ISSN |
0048-9697 |
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yes |
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Serial |
7960 |
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Author |
A. Baranov, R. Tenzer, A. Morelli |
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Title |
Updated Antarctic crustal model |
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Journal |
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Year |
2021 |
Publication |
Gondwana Research |
Abbreviated Journal |
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Volume |
89 |
Issue |
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Pages |
1-18 |
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Keywords |
Antarctica Crustal structure Gondwana Sediments |
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Abstract |
We use seismic data together with a subglacial bedrock relief from the BEDMAP2 database to obtain a new three-layer model of the consolidated (crystalline) crust of Antarctica that locally improves the global seismic crustal model CRUST1.0. We collect suitable data for constructing crustal layers, analyse them and build maps of the crustal layer thickness and seismic velocities. We use the subglacial relief according to a tectonic configuration and then interpolate data using a statistical kriging method. The P-wave velocity information from old seismic profiles have been supplemented with the new shear-wave velocity models. We adjust the thickness of crustal layers by multiplying a total crustal thickness by a percentage ratio of each individual layer at each point. Our results reveal large variations in seismic velocities between different crustal blocks forming Antarctica. The most pronounced differences exist between East and West Antarctica. In East Antarctica, a high P-wave velocity (vP > 7 km/s) layer in the lower crust is absent. The P-wave velocity in the lower crust changes from 6.1 km/s beneath the Lambert Rift to 6.9 km/s beneath the Wilkes Basin. In West Antarctica, a thick mafic lower crust is characterized by large P-wave velocities, ranging from 7.0 km/s under the Ross Sea to 7.3 km/s under the Byrd Basin. In contrast, velocities in the lower crust beneath the Transantarctic and Ellsworth-Whitmore Mountains are ~6.8 km/s. The P-wave velocities in the upper crust in East Antarctica are within the range 5.5–6.4 km/s. The upper crust of West Antarctica is characterized by the P-wave velocities of 5.6–6.3 km/s. The P-wave velocities in the middle crust vary within 5.9–6.6 km/s in East Antarctica and within 6.3–6.5 km/s in West Antarctica. A low-velocity layer (5.8–5.9 km/s) is detected at depth of ~20–25 km beneath the Princes Elizabeth Land. |
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Programme |
133 |
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ISSN |
1342-937X |
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yes |
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Serial |
7994 |
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Author |
Casey Youngflesh, Yun Li, Heather J. Lynch, Karine Delord, Christophe Barbraud, Rubao Ji, Stephanie Jenouvrier |
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Title |
Lack of synchronized breeding success in a seabird community: extreme events, niche separation, and environmental variability |
Type |
Journal |
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Year |
2021 |
Publication |
Oikos |
Abbreviated Journal |
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Volume |
130 |
Issue |
11 |
Pages |
1943-1953 |
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Keywords |
Antarctica environmental indicators extreme events global change niche separation synchrony |
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Abstract |
Synchrony in ecological systems, the degree to which elements respond similarly over time or space, can inform our understanding of how ecosystems function and how they are responding to global change. While studies of ecological synchrony are often focused on within-species dynamics, synchrony among species may provide important insights into how dynamics of one species are indicative of conditions relevant to the larger community, with both basic and applied implications. Ecological theory suggests there may be conditions under which communities might exhibit increased synchrony, however, the degree to which these patterns are borne out in natural systems is currently unknown. We used long-term breeding success data from a community of Antarctic seabirds to assess the degree of interspecific, community synchrony, and the role that extreme events play in driving these dynamics. We assessed theoretical links between community synchrony, niche separation, and environmental variability using data from this and three other seabird communities as well as a simulation study. Results show that reproductive success for individual species in the Antarctic seabird community fluctuated relatively independently from one another, resulting in little synchrony across this community, outside of extreme years. While an exceptionally poor year for a given species was not necessarily associated with an exceptionally poor year for any other species, one community-wide extreme year existed. When compared to other seabird communities, this group of Antarctic seabirds exhibited lower overall synchrony and higher estimated niche separation, supporting theoretical predictions. Empirical and simulation-derived results suggest that communities where temporal variation is small for conditions in which species respond substantially differently, and large for conditions in which species respond similarly, may exhibit more synchronous dynamics. Identifying where and why synchronous dynamics might be more apparent has the potential to inform how ecological communities might respond to future global change. |
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Programme |
109 |
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ISSN |
1600-0706 |
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yes |
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Call Number |
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Serial |
8385 |
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Author |
Lara D. Shepherd, Colin M. Miskelly, Yves Cherel, Alan J. D. Tennyson |
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Title |
Genetic identification informs on the distributions of vagrant Royal (Eudyptes schlegeli) and Macaroni (Eudyptes chrysolophus) Penguins |
Type |
Journal |
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Year |
2021 |
Publication |
Polar Biology |
Abbreviated Journal |
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Volume |
44 |
Issue |
12 |
Pages |
2299-2306 |
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Keywords |
Antarctica Eudyptes chrysolophus Eudyptes schlegeli Genetic identification Penguin distribution Predation |
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Abstract |
Understanding the movements of animals that spend much of their life at sea is difficult but important for effective conservation. Determining the at-sea distributions of Macaroni (Eudyptes chrysolophus) and Royal (Eudyptes schlegeli) Penguins poses particular challenges, including their occurrence in remote locations and difficulties in species identification owing to overlap in morphological characters, particularly in immature birds. Here we use DNA sequencing to examine vagrant Macaroni and Royal Penguins from Antarctica and New Zealand in order to improve understanding of their non-breeding distributions. Our sampling included samples from living birds, museum specimens and scavenged penguin remains recovered from the stomachs of Antarctic toothfish (Dissostichus mawsoni) caught north of the Ross Sea. Mitochondrial control region (HVRI) sequences indicated that the two samples from New Zealand were likely Royal Penguins as were the scavenged penguins. Both Macaroni and Royal Penguins were detected at Terre Adélie, Antarctica, despite the nearest breeding colony of Macaroni Penguins being 4000 km away. We provide the first evidence of Royal Penguins reaching the Ross Dependency. All but one of the vagrants were immature birds, supporting suggestions that this age group is the most likely to disperse large distances from the breeding colonies. Our study demonstrates how DNA sequences can assist in identifying taxa with similar or overlapping morphologies, as well as fragmentary bird remains. |
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Programme |
109 |
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ISSN |
1432-2056 |
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yes |
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Serial |
8365 |
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Author |
Helena P. Baird, Seunggwan Shin, Rolf G. Oberprieler, Maurice Hullé, Philippe Vernon, Katherine L. Moon, Richard H. Adams, Duane D. McKenna, Steven L. Chown |
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Title |
Fifty million years of beetle evolution along the Antarctic Polar Front |
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Journal |
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Year |
2021 |
Publication |
Proceedings of the National Academy of Sciences |
Abbreviated Journal |
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Volume |
118 |
Issue |
24 |
Pages |
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Keywords |
Antarctica herbivory island biogeography paleoclimate species radiation |
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Abstract |
Global cooling and glacial–interglacial cycles since Antarctica’s isolation have been responsible for the diversification of the region’s marine fauna. By contrast, these same Earth system processes are thought to have played little role terrestrially, other than driving widespread extinctions. Here, we show that on islands along the Antarctic Polar Front, paleoclimatic processes have been key to diversification of one of the world’s most geographically isolated and unique groups of herbivorous beetles—Ectemnorhinini weevils. Combining phylogenomic, phylogenetic, and phylogeographic approaches, we demonstrate that these weevils colonized the sub-Antarctic islands from Africa at least 50 Ma ago and repeatedly dispersed among them. As the climate cooled from the mid-Miocene, diversification of the beetles accelerated, resulting in two species-rich clades. One of these clades specialized to feed on cryptogams, typical of the polar habitats that came to prevail under Miocene conditions yet remarkable as a food source for any beetle. This clade’s most unusual representative is a marine weevil currently undergoing further speciation. The other clade retained the more common weevil habit of feeding on angiosperms, which likely survived glaciation in isolated refugia. Diversification of Ectemnorhinini weevils occurred in synchrony with many other Antarctic radiations, including penguins and notothenioid fishes, and coincided with major environmental changes. Our results thus indicate that geo-climatically driven diversification has progressed similarly for Antarctic marine and terrestrial organisms since the Miocene, potentially constituting a general biodiversity paradigm that should be sought broadly for the region’s taxa. |
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136 |
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0027-8424, 1091-6490 |
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yes |
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Call Number |
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Serial |
8087 |
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Author |
Natasha Roy, James Woollett, Najat Bhiry, Isabel Lemus-Lauzon, Ann Delwaide, Dominique Marguerie |
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Title |
Anthropogenic and climate impacts on subarctic forests in the Nain region, Nunatsiavut: Dendroecological and historical approaches |
Type |
Journal |
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Year |
2021 |
Publication |
Écoscience |
Abbreviated Journal |
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Volume |
28 |
Issue |
3-4 |
Pages |
361-376 |
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Keywords |
approches historiques croissance démographique Dendrochronologie Dendrochronology détente de croissance radiale growth release historical approaches Nain Nunatsiavut population growth |
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Abstract |
Several recent dendrochronological, macrofossil and palynological studies have surveyed modern spruce forests at multiple locations in the Nain region of coastal Nunatsiavut (north-central Labrador) in order to reconstruct past forest composition, growth rates, species diversity and harvesting patterns. The present paper synthesizes original and previously collected data to evaluate the extent to which the dynamics of the region’s spruce forests over the past five centuries have been related to anthropogenic impacts. In three key case studies, Picea growth release events demonstrate multiple isolated forest disturbances prior to the late 19th century. In general, these events correspond to the local human settlement history rather than to regional climatic trends, suggesting that ongoing human impacts on the forest extend as far back as the 17th century. Disturbance regimes accelerated by ca 1875 and afterward in all of the study sites. This increase in forest disturbance corresponds to increased demands for wood triggered by socio-economic changes experienced by the region’s Inuit and Settler communities. Ongoing surveys demonstrate the presence of markers of human exploitation of forests throughout the study region, and especially in coastal locations, suggesting that anthropogenic impacts are in fact generalised and not limited to specific areas of recent settlement. |
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Programme |
1080 |
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ISSN |
1195-6860 |
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yes |
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Serial |
8251 |
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Author |
Mathilde Poirier, Dominique Fauteux, Gilles Gauthier, Florent Domine, Jean-François Lamarre |
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Title |
Snow hardness impacts intranivean locomotion of arctic small mammals |
Type |
Journal |
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Year |
2021 |
Publication |
Ecosphere |
Abbreviated Journal |
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Volume |
12 |
Issue |
11 |
Pages |
e03835 |
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Keywords |
Arctic burrowing behavior digging fossorial hardness lemming locomotion rain-on-snow rodent snow subnivean tunnel |
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Abstract |
Fossorial locomotion is often considered as the most energetically costly of all terrestrial locomotion. Small arctic rodents, such as lemmings, dig tunnels not only in the soil but also through the snowpack, which is present for over 8 months of the year. Lemmings typically dig in the softest snow layer called the depth hoar but with climate change, melt-freeze and rain-on-snow (ROS) events are expected to increase in the Arctic, leading to a higher frequency of hardened snowpacks. We assessed the impacts of snow hardness on the locomotion of two lemming species showing different morphological adaptations for digging. We hypothesized that an increase in snow hardness would (1) decrease lemming performance and (2) increase their effort while digging, but those responses would differ between lemming species. We exposed four brown lemmings (Lemmus trimucronatus) and three collared lemmings (Dicrostonyx groenlandicus) to snow of different hardness (soft, hard, and ROS) during 30-min trials (n = 63 trials) in a cold room and filmed their behavior. We found that the digging speed and tunnel length of both species decreased with snow hardness and density, underlining the critical role of snow properties in affecting lemming digging performance. During the ROS trials, time spent digging by lemmings increased considerably and they also started using their incisors to help break the hard snow, validating our second hypothesis. Overall, digging performance was higher in collared lemmings, the species showing more morphological adaptations to digging, than in brown lemmings. We conclude that the digging performance of lemming is highly dependent on snowpack hardness and that the anticipated increase in ROS events may pose a critical energetic challenge for arctic rodent populations. |
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Programme |
1042 |
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ISSN |
2150-8925 |
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yes |
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Call Number |
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Serial |
8028 |
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Author |
Éric Bernard, Jean-Michel Friedt, Madeleine Griselin |
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Title |
Snowcover Survey over an Arctic Glacier Forefield: Contribution of Photogrammetry to Identify “Icing” Variability and Processes |
Type |
Journal |
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Year |
2021 |
Publication |
Remote Sensing |
Abbreviated Journal |
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Volume |
13 |
Issue |
10 |
Pages |
1978 |
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arctic cryosphere moraine photogrammetry snow water equivalent snowcover spatial dynamics UAV-SfM |
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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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