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Author |
Chengsheng Zhu, Maximilian Miller, Nicholas Lusskin, Benoît Bergk Pinto, Lorrie Maccario, Max Häggblom, Timothy Vogel, Catherine Larose, Yana Bromberg |
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Title  |
Snow microbiome functional analyses reveal novel aspects of microbial metabolism of complex organic compounds |
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Journal |
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Year |
2020 |
Publication |
MicrobiologyOpen |
Abbreviated Journal |
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Volume |
9 |
Issue |
9 |
Pages |
e1100 |
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Keywords |
metagenome metatranscriptome mi-faser snow microbiome |
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Abstract |
Microbes active in extreme cold are not as well explored as those of other extreme environments. Studies have revealed a substantial microbial diversity and identified cold-specific microbiome molecular functions. We analyzed the metagenomes and metatranscriptomes of 20 snow samples collected in early and late spring in Svalbard, Norway using mi-faser, our read-based computational microbiome function annotation tool. Our results reveal a more diverse microbiome functional capacity and activity in the early- vs. late-spring samples. We also find that functional dissimilarity between the same-sample metagenomes and metatranscriptomes is significantly higher in early than late spring samples. These findings suggest that early spring samples may contain a larger fraction of DNA of dormant (or dead) organisms, while late spring samples reflect a new, metabolically active community. We further show that the abundance of sequencing reads mapping to the fatty acid synthesis-related microbial pathways in late spring metagenomes and metatranscriptomes is significantly correlated with the organic acid levels measured in these samples. Similarly, the organic acid levels correlate with the pathway read abundances of geraniol degradation and inversely correlate with those of styrene degradation, suggesting a possible nutrient change. Our study thus highlights the activity of microbial degradation pathways of complex organic compounds previously unreported at low temperatures. |
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1192 |
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2045-8827 |
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yes |
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Call Number |
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Serial |
7964 |
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Author |
F. Pitout, A. Marchaudon, K. J. Trattner, J. Berchem, H. Laakso, C. P. Escoubet |
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Title |
Simultaneous Polar and Cluster Observations in the Northern and Southern Middle-Altitude Polar Cusps Around Equinox |
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Journal |
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Year |
2020 |
Publication |
Journal of Geophysical Research: Space Physics |
Abbreviated Journal |
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Volume |
125 |
Issue |
12 |
Pages |
e2020JA028346 |
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Keywords |
dayside magnetosphere hemispheric asymmetry polar cusp |
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Abstract |
We present an event of simultaneous observations of the northern and southern middle-altitude polar cusps by the Polar spacecraft and Cluster fleet that occurred on 23 September 2004. We examine the possible asymmetries in the fields and plasma parameters, although the proximity of the equinox should limit these asymmetries. Ion sensors reveal two dispersions in both cusps, and data analysis leads to the conclusion that those dispersions are due to pulsed reconnection at a single X-line, which runs along the subsolar magnetopause. While the electromagnetic and particle energy fluxes injected in both cusp are globally very similar, we report significant differences in ion dispersions, width of the low-latitude boundary layer, and peak convection velocities. We ascribe these differences to the dipole tilt that introduces an asymmetry in the magnetosheath flow at the exterior cusps. |
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312 |
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ISSN |
2169-9402 |
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yes |
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Call Number |
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Serial |
6363 |
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Author |
Adriane Cristina Mendes Prado, Mauricio Tizziani Pazianotto, Jose Manuel Quesada Molina, Miguel Antonio Cortes-Giraldo, Guillaume Hubert, Marlon Antonio Pereira, Claudio Antonio Federico |
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Title |
Simulation of Cosmic Radiation Transport Inside Aircraft for Safety Applications |
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Journal |
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Year |
2020 |
Publication |
IEEE Transactions on Aerospace and Electronic Systems |
Abbreviated Journal |
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Volume |
56 |
Issue |
5 |
Pages |
3462-3475 |
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Keywords |
Aerospace electronics Aircraft Aircraft manufacture Aircraft simulation Atmospheric modeling Computational modeling cosmic radiation neutron fluence rate Neutrons safety single event effect |
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Abstract |
During the flight, an aircraft is submitted to a radiation environment composed of cosmic-ray-induced particles (CRIP) of which neutrons are responsible for approximately 40% of the crew effective dose and are the main cause of single event effects (SEE) in avionics systems at flight altitudes. A model of Learjet aircraft was developed on Monte Carlo simulation using the MCNPX code in order to detail the CRIP field inside the aircraft. The radiation source modeling was previously developed by a computational platform that simulates the energy and angular distributions of the CRIP along the atmosphere. In this article, we determined the variation of the neutron radiation field in several positions inside the aircraft at 11- and 18-km altitudes and for both equatorial and polar regions. The results suggest that the maximum variation of neutron fluence rate between different positions inside the aircraft shows a tendency of higher differences for a lower energy threshold (thermal and E > 1 MeV) in comparison with those differences for a higher energy threshold (E > 10 MeV). Moreover, the angular distribution results show relevant differences between positions inside aircraft, mainly for thermal neutrons close to the fuel. The general tendency is to enhance these discrepancies for devices with new technologies, due to their lower energy threshold for SEE occurrences. |
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1112 |
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ISSN |
1557-9603 |
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yes |
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Call Number |
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Serial |
7959 |
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Author |
Thomas A. Clay, Rocío Joo, Henri Weimerskirch, Richard A. Phillips, Olivier den Ouden, Mathieu Basille, Susana Clusella-Trullas, Jelle D. Assink, Samantha C. Patrick |
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Title |
Sex-specific effects of wind on the flight decisions of a sexually dimorphic soaring bird |
Type |
Journal |
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Year |
2020 |
Publication |
Journal of Animal Ecology |
Abbreviated Journal |
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Volume |
89 |
Issue |
8 |
Pages |
1811-1823 |
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Keywords |
biologging foraging behaviour hidden Markov model movement ecology niche specialization optimization sexual segregation wandering albatross |
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Abstract |
In a highly dynamic airspace, flying animals are predicted to adjust foraging behaviour to variable wind conditions to minimize movement costs. Sexual size dimorphism is widespread in wild animal populations, and for large soaring birds which rely on favourable winds for energy-efficient flight, differences in morphology, wing loading and associated flight capabilities may lead males and females to respond differently to wind. However, the interaction between wind and sex has not been comprehensively tested. We investigated, in a large sexually dimorphic seabird which predominantly uses dynamic soaring flight, whether flight decisions are modulated to variation in winds over extended foraging trips, and whether males and females differ. Using GPS loggers we tracked 385 incubation foraging trips of wandering albatrosses Diomedea exulans, for which males are c. 20% larger than females, from two major populations (Crozet and South Georgia). Hidden Markov models were used to characterize behavioural states—directed flight, area-restricted search (ARS) and resting—and model the probability of transitioning between states in response to wind speed and relative direction, and sex. Wind speed and relative direction were important predictors of state transitioning. Birds were much more likely to take off (i.e. switch from rest to flight) in stronger headwinds, and as wind speeds increased, to be in directed flight rather than ARS. Males from Crozet but not South Georgia experienced stronger winds than females, and males from both populations were more likely to take-off in windier conditions. Albatrosses appear to deploy an energy-saving strategy by modulating taking-off, their most energetically expensive behaviour, to favourable wind conditions. The behaviour of males, which have higher wing loading requiring faster speeds for gliding flight, was influenced to a greater degree by wind than females. As such, our results indicate that variation in flight performance drives sex differences in time–activity budgets and may lead the sexes to exploit regions with different wind regimes. |
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Programme |
109 |
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ISSN |
1365-2656 |
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yes |
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Call Number |
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Serial |
8077 |
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Author |
Maxime Pineaux, Thomas Merkling, Etienne Danchin, Scott Hatch, David Duneau, Pierrick Blanchard, Sarah Leclaire |
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Title |
Sex and hatching order modulate the association between MHC-II diversity and fitness in early-life stages of a wild seabird |
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Journal |
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Year |
2020 |
Publication |
Molecular Ecology |
Abbreviated Journal |
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Volume |
29 |
Issue |
17 |
Pages |
3316-3329 |
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Keywords |
divergent allele advantage fitness heterozygote advantage immunity Ixodes uriae parasite-mediated selection |
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Abstract |
Genes of the major histocompatibility complex (MHC) play a pivotal role in parasite resistance, and their allelic diversity has been associated with fitness variations in several taxa. However, studies report inconsistencies in the direction of this association, with either positive, quadratic or no association being described. These discrepancies may arise because the fitness costs and benefits of MHC diversity differ among individuals depending on their exposure and immune responses to parasites. Here, we investigated in black-legged kittiwake (Rissa tridactyla) chicks whether associations between MHC class-II diversity and fitness vary with sex and hatching order. MHC-II diversity was positively associated with growth and tick clearance in female chicks, but not in male chicks. Our data also revealed a positive association between MHC-II diversity and survival in second-hatched female chicks (two eggs being the typical clutch size). These findings may result from condition-dependent parasite infections differentially impacting sexes in relation to hatching order. We thus suggest that it may be important to account for individual heterogeneities in traits that potentially exert selective pressures on MHC diversity in order to properly predict MHC–fitness associations. |
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Programme |
1162 |
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ISSN |
1365-294X |
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Approved |
yes |
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Call Number |
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Serial |
8311 |
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Author |
Louis Le Toumelin, Charles Amory, Vincent Favier, Christoph Kittel, Stefan Hofer, Xavier Fettweis, Hubert Gallée, Vinay Kayetha |
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Title |
Sensitivity of the surface energy budget to drifting snow as simulated by MAR in coastal Adelie Land, Antarctica |
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Journal |
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Year |
2020 |
Publication |
The Cryosphere |
Abbreviated Journal |
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Volume |
15 |
Issue |
8 |
Pages |
3595-3614 |
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Abstract |
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Programme |
411,1013 |
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Thesis |
Bachelor's thesis |
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ISSN |
1994-0416 |
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Approved |
yes |
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Call Number |
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Serial |
7946 |
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Author |
Guillaumot Charlène, Danis Bruno, Saucède Thomas |
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Title |
Selecting environmental descriptors is critical for modelling the distribution of Antarctic benthic species |
Type |
Journal |
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Year |
2020 |
Publication |
Polar Biology |
Abbreviated Journal |
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Volume |
43 |
Issue |
9 |
Pages |
1363-1381 |
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Keywords |
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Abstract |
Species distribution models (SDMs) are increasingly used in ecological and biogeographic studies by Antarctic biologists, including for conservation and management purposes. During the modelling process, model calibration is a critical step to ensure model reliability and robustness, especially in the case of SDMs, for which the number of selected environmental descriptors and their collinearity is a recurring issue. Boosted regression trees (BRT) was previously considered as one of the best modelling approach to correct for this type of bias. In the present study, we test the performance of BRT in modelling the distribution of Southern Ocean species using different numbers of environmental descriptors, either collinear or not. Models are generated for six sea star species with contrasting ecological niches and wide distribution ranges over the entire Southern Ocean. For the six studied species, overall modelling performance is not affected by the number of environmental descriptors used to generate models, BRT using the most informative descriptors and minimizing model overfitting. However, removing collinear descriptors also helps reduce model overfitting. Our results confirm that BRTs may perform well and are relevant to deal with complex and redundant environmental information for Antarctic biodiversity distribution studies. Selecting a limited number of non-collinear descriptors before modelling may generate simpler models and facilitate their interpretation. The modelled distributions do not differ noticeably between the different species despite contrasting species ecological niches. This unexpected result stresses important limitations in using SDMs for broad scale spatial studies, based on limited, spatially aggregated data, and low-resolution descriptors. |
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Programme |
1044,1124 |
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Bachelor's thesis |
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ISSN |
1432-2056 |
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yes |
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Call Number |
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Serial |
8184 |
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Author |
Crouzet N., Mékarnia D., Agabi K., Guillot T., Abe L., Bayliss D., Deeg H., Murgas F., Palle E., Schmider F. |
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Title |
Searching for long period transiting exoplanets with ASTEP South at Dome C, Antarctica |
Type |
Book Chapter |
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Year |
2020 |
Publication |
SCAR 2020 Open Science Conference (abstract only) |
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Keywords |
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Abstract |
Much of our understanding of gas giant exoplanets come from those transiting in front of bright stars at short orbital separations (P ~ 3 days, a ~ 0.05 au). However, these |
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Programme |
1066 |
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Bachelor's thesis |
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yes |
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Call Number |
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Serial |
7807 |
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Author |
Amandine Gamble, Henri Weimerskirch, Thierry Boulinier |
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Title |
Seabirds blinded by ticks |
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Journal |
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Year |
2020 |
Publication |
Frontiers in Ecology and the Environment |
Abbreviated Journal |
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Volume |
18 |
Issue |
6 |
Pages |
322-322 |
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Abstract |
In December 2017, on Possession Island (part of the Crozet Archipelago in the southern Indian Ocean), we observed two breeding white‐chinned petrels (Procellaria aequinoctialis ) with very high levels of tick (Ixodes kerguelenensis ) infestation on both eyes. This degree of infestation was likely responsible for the birds’ death. Although this rare observation may seem anecdotal, it reveals that ticks can be fatal for a long‐lived colonial seabird species, in this case one that is already under pressure from fisheries bycatch and predation by introduced black rats (Rattus rattus ). It also raises questions about the frequency and spatial distribution of such a phenomenon and the conditions that may have been responsible for its occurrence. Such high parasite loads imply high local tick abundances but also a lack of preening by the partner. Could this be linked to the recent death of the partner? Infestations by ticks can affect the health of hosts through blood loss, the injection of toxins, and the transmission of infectious agents. In this instance, the mechanical blocking of eyesight may also have affected the birds’ behavior. The potential impact of climate change on local parasitic infestation levels is another important question. Parasites and diseases can harm endangered species in polar and subpolar areas, and could play critical roles in some circumstances. |
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Programme |
1151 |
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Bachelor's thesis |
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ISSN |
1540-9309 |
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yes |
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Serial |
7797 |
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Author |
David Boertmann, Flemming Merkel, Olivier Gilg |
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Title |
Seabird Breeding Colonies in East and North Greenland: A Baseline |
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Journal |
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Year |
2020 |
Publication |
ARCTIC |
Abbreviated Journal |
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Volume |
73 |
Issue |
1 |
Pages |
20-39 |
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Keywords |
climate change colonial seabirds distribution Greenland |
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Abstract |
This paper presents the results of a number of aircraft- and boat-based surveys for seabird breeding colonies in East and North Greenland carried out in the period 2003 to 2018 and gives the first comprehensive overview of the distribution and size of the seabird breeding colonies in this remote and mainly uninhabited region. Seventeen seabird species breed in approximately 800 sites distributed very unevenly along the coasts, with high concentrations at the polynyas and long stretches with very few breeding seabirds. Climate changes are in full progress in East and North Greenland, especially affecting the sea ice regime, and seabirds are expected to respond to these changes in different ways. For example, since the 1980s, Common Eiders (Somateria mollissima) have extended their breeding range more than two latitudinal degrees towards the north, now reaching the northernmost land on Earth. Lesser Black-backed Gulls (Larus fuscus) and Great Cormorants (Phalacrocorax carbo) have immigrated, and Sabine’s Gulls (Xema sabini) have increased and extended their range. Besides presenting survey results, this report may also serve as a baseline for future studies of the abundance of breeding seabirds in East and North Greenland. |
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1036 |
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1923-1245 |
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yes |
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Call Number |
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Serial |
7681 |
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