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Y. Quesnel, W. Zylberman, P. Rochette, M. Uehara, J. Gattacceca, G. R. Osinski, P. Dussouillez, C. Lepaulard, C. Champollion |
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Title |
Geophysical signature of the Tunnunik impact structure, Northwest Territories, Canada |
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Year |
2020 |
Publication |
Meteoritics & Planetary Science |
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Volume |
55 |
Issue |
3 |
Pages |
480-495 |
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Abstract  |
In 2011, the discovery of shatter cones confirmed the 28 km diameter Tunnunik complex impact structure, Northwest Territories, Canada. This study presents the first results of ground-based electromagnetic, gravimetric, and magnetic surveys over this impact structure. Its central area is characterized by a 10 km wide negative gravity anomaly of about 3 mGal amplitude, roughly corresponding to the area of shatter cones, and associated with a positive magnetic field anomaly of 120 nT amplitude and 3 km wavelength. The latter correlates well with the location of the deepest uplifted strata, an impact-tilted Proterozoic dolomite layer of the Shaler Supergroup exposed near the center of the structure and intruded by dolerite dykes. Locally, electromagnetic field data unveil a conductive superficial formation which corresponds to an 80–100 m thick sand layer covering the impact structure. Based on the measurements of magnetic properties of rock samples, we model the source of the magnetic anomaly as the magnetic sediments of the Shaler Supergroup combined with a core of uplifted crystalline basement with enhanced magnetization. More classically, the low gravity signature is attributed to a reduction in density measured on the brecciated target rocks and to the isolated sand formations. However, the present-day fractured zone does not extend deeper than 1 km in our model, indicating a possible 1.5 km of erosion since the time of impact, about 430 Ma ago. |
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1139 |
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1945-5100 |
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yes |
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8266 |
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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 |
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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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109 |
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1365-2656 |
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8077 |
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Yan Axel Gómez Coutouly, Angela K. Gore, Charles E. Holmes, Kelly E. Graf, Ted Goebel |
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Title |
“Knapping, My Child, is Made of Errors”: Apprentice Knappers at Swan Point and Little Panguingue Creek, Two Prehistoric Sites in Central Alaska |
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Journal |
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Year |
2020 |
Publication |
Lithic Technology |
Abbreviated Journal |
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Volume |
46 |
Issue |
1 |
Pages |
2-26 |
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Keywords |
Alaska apprenticeship lithic technology microblade prehistory |
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Abstract |
In Beringia, as in many other parts of the world, stone tools are the main diagnostic cultural artifact for understanding prehistoric societies. The analysis of lithic assemblages is the basis for establishing connections between sites and techno-complexes. Through highlighting major technological trends, archaeologists are able to interpret processes such as cultural continuity and migrations. Here we present a fine-grained analysis of two assemblages to perceive in detail the individuals behind the lithic productions, more specifically apprentice knappers. Although recognition of apprenticeship in a prehistoric context is not new, this is the first such study for Alaska and Beringia. We focus on two distinct assemblages with microblade technology: the late Pleistocene component of Swan Point CZ4b (Tanana valley) and the early Holocene component of Little Panguingue Creek C2 (Nenana valley), both in central Alaska. |
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1217 |
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0197-7261 |
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0197-7261 |
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yes |
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Serial |
7632 |
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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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Thesis |
Bachelor's thesis |
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1540-9309 |
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yes |
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7797 |
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Author |
Lorène Julia Marchand, Michèle Tarayre, Thomas Dorey, Yann Rantier, Françoise Hennion |
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Title |
Morphological variability of cushion plant Lyallia kerguelensis (Caryophyllales) in relation to environmental conditions and geography in the Kerguelen Islands: implications for cushion necrosis and climate change |
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Journal |
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Year |
2020 |
Publication |
Polar Biology |
Abbreviated Journal |
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Volume |
44 |
Issue |
1 |
Pages |
17-30 |
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Abstract |
In recent decades, climate change has been faster in various parts of the world. Within species, to counter rapid climate changes shift of geographical area, individuals’ plastic responses or populations’ genetic adaptation might occur. The sub-Antarctic islands are subject to one of the most rapid climate changes on earth, with already visible impacts on native vegetation. Such might be the case of Lyallia kerguelensis a cushion plant strictly endemic to the Kerguelen Islands. In L. kerguelensis, necrotic parts were observed in cushions these last decades and possibly related to water stress. We analysed morphological variability of L. kerguelensis, including necrosis extent, across 19 populations spanning a wide range of environments across the Kerguelen Islands. Inter-population variations in the cushion surface area, shape and compactness were well explained by topography, degree of wind exposure, slope aspect, proportions of coarse sand and bare soil, and geographical distance between populations. All these variables are related to wind intensity and water availability. Moreover, in cushions with less than 10% necrosis in surface area, necrosis extent was positively correlated to soil sodium. Sodium availability might reduce the plant’s capacity for osmotic adjustment in face of other abiotic stresses, such as water stress. We conclude that cushion morphology may have the capacity to adjust to environmental variation, including aspects of climate change, but that cushion necrosis may be accelerated in the driest and most saline environments. |
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Programme |
1116 |
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Bachelor's thesis |
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ISSN |
1432-2056 |
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yes |
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Serial |
7793 |
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Author |
Barbara Delmonte, Holly Winton, Mélanie Baroni, Giovanni Baccolo, Margareta Hansson, Per Andersson, Carlo Baroni, Maria Cristina Salvatore, Luca Lanci, Valter Maggi |
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Title |
Holocene dust in East Antarctica: Provenance and variability in time and space |
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Journal |
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Year |
2020 |
Publication |
The Holocene |
Abbreviated Journal |
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Volume |
30 |
Issue |
4 |
Pages |
546-558 |
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Keywords |
East Antarctica ice cores dust dust stratigraphy Holocene provenance |
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Abstract |
In this paper, we provide a comprehensive overview of the state-of-knowledge of dust flux and variability in time and space in different sectors of East Antarctica during the Holocene. By integrating the literature data with new evidences, we discuss the dust flux and grain-size variability during the current interglacial and its provenance in the innermost part of the East Antarctic plateau as well as in peripheral regions located close to the Transantarctic Mountains. The local importance of aeolian mineral dust aerosol deflated from low-elevation areas of peripheral East Antarctica is also discussed in the light of new data from several coastal, low-elevation sites. |
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1145 |
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0959-6836 |
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yes |
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7610 |
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Author |
Sophie M. Dupont, Christophe Barbraud, Olivier Chastel, Karine Delord, Charline Parenteau, Cécile Ribout, Frédéric Angelier |
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Title |
Do repeated captures and handling affect phenotype and survival of growing Snow Petrel (Pagodroma nivea)? |
Type |
Journal |
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Year |
2020 |
Publication |
Polar Biology |
Abbreviated Journal |
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Volume |
43 |
Issue |
6 |
Pages |
637-646 |
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Abstract |
In vertebrates, developmental conditions can affect not only fledging success but also the phenotype of the offspring, with potential long-term consequences on adult performance. However, surprisingly the potential impact of anthropogenic disturbance on developing chicks is rarely investigated, notably in Antarctic wildlife. In this study, we specifically investigated the effects of repeated nest visits, capture, and handling on offspring survival and several complementary offspring phenotypic traits in the Snow Petrel (Pagodroma nivea) chicks after thermal emancipation. We did not find any significant effect of our disturbance protocol on the morphology (body size, body mass, body condition), the physiology (breath rate, stress-induced corticosterone levels) and the behaviour (defense behaviour) of developing Snow Petrels. This specific disturbance protocol did not have any significant effect on chick survival, but there was a non-significant trend towards a lower survival for the disturbed group (p = 0.1006), which showed an especially high mortality during a period of repeated snow storms. To conclude, investigator disturbance seems to have little effect on Snow Petrel chicks after thermal emancipation, but to remain cautious, we recommend to avoid capture and handling of Snow Petrel chicks during or soon after inclement weather. |
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109 |
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1432-2056 |
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yes |
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Serial |
7661 |
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Author |
Pierre Blévin, Scott A. Shaffer, Paco Bustamante, Frédéric Angelier, Baptiste Picard, Dorte Herzke, Børge Moe, Geir Wing Gabrielsen, Jan Ove Bustnes, Olivier Chastel |
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Title |
Contaminants, prolactin and parental care in an Arctic seabird: Contrasted associations of perfluoroalkyl substances and organochlorine compounds with egg-turning behavior |
Type |
Journal |
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Year |
2020 |
Publication |
General and comparative endocrinology |
Abbreviated Journal |
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Volume |
291 |
Issue |
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Pages |
113420 |
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Keywords |
Black-legged kittiwake Corticosterone Egg-loggers Incubation behaviors Mercury Organochlorine compounds Perfluoroalkyl substances Prolactin |
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Abstract |
Incubating eggs represents a trade-off for parent birds between spending enough time fasting to take care of the clutch and to get enough nutrients for self-maintenance. It is believed that the pituitary hormone prolactin plays an important role in such allocation processes. Incubation does not solely imply the active warming of the eggs but also the active egg-turning to facilitate absorption of albumen by the embryo, reduce malposition and prevent the embryo from adhering to the inner shell membrane. However, how prolactin secretion is related to egg-turning behaviors is presently poorly addressed. In addition, several environmental contaminants can affect parental care behaviors through their endocrine disrupting properties but the effects of such contaminants on egg-turning behaviors remain so far unexplored. Using artificial eggs equipped with miniaturized data loggers, we investigated the relationships between egg-turning behaviors, prolactin secretion and contaminants burden in Arctic black-legged kittiwakes (Rissa tridactyla). Specifically, we examined the relationships between blood concentrations of poly- and perfluoroalkyl substances (PFASs), organochlorines (OCs), mercury (Hg), plasma prolactin levels and both egg-turning frequency and angular change. We also incorporated baseline corticosterone levels since this glucocorticoid is known to affect parental care. Plasma prolactin levels were positively related to angular change in female kittiwakes while corticosterone was not related to egg-turning behaviors in either sex. Hg was not related to egg-turning behaviors in either sex. We found contrasting associations between OCs and PFASs, since polychlorinated biphenyls (PCBs) were negatively associated with angular change in females, contrary to linear perfluorooctanesulfonate (PFOSlin) and perfluoroalkyl carboxylic acids (PFCAs) which were positively related to egg-turning frequency and angular change in both sexes. Additionally, PFASs concentrations were positively related to prolactin levels in female kittiwake. The possible stimulation of prolactin secretion by PFASs could therefore make adult kittiwakes to allocate more time taking care of their eggs, and thus possibly modify the trade-off between spending enough time caring for the clutch and obtaining enough nutrients at sea. |
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330 |
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ISSN |
0016-6480 |
ISBN |
0016-6480 |
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yes |
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7628 |
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Author |
Liubomira Romanova, Charles Stépanoff, Norbert Telmon, Eric Crubézy |
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Title |
Health access inequities and magic medicine: the first ancient evidence? |
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Journal |
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Year |
2020 |
Publication |
The Lancet |
Abbreviated Journal |
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Volume |
395 |
Issue |
10233 |
Pages |
1343-1344 |
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Abstract |
Inequities in access to the latest advances in health care and effective drugs constitute public health problems today,1 but was this also the case in ancient societies when practitioners used traditional medicines with limited means? The excavation of frozen graves in Yakutia (present day eastern Siberia, Russia) dating from 1700 CE2 led to the identification of a woman, buried almost naked, covered with a magnificent robe and with half a horse bit in her mouth (figure). The other half of the horse bit was found in the trunk behind her head with her earrings, bracelets, and signet rings. |
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Programme |
1038 |
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Bachelor's thesis |
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Elsevier |
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ISBN |
0140-6736, 1474-547X |
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yes |
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Serial |
7666 |
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Author |
Kévin Fourteau, Fabien Gillet-Chaulet, Patricia Martinerie, Xavier Faïn |
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Title |
A Micro-Mechanical Model for the Transformation of Dry Polar Firn Into Ice Using the Level-Set Method |
Type |
Journal |
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Year |
2020 |
Publication |
Frontiers in Earth Science |
Abbreviated Journal |
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Volume |
8 |
Issue |
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Pages |
101 |
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Abstract |
Interpretation of greenhouse gas records in polar ice cores requires a good understanding of the mechanisms controlling gas trapping in polar ice, and therefore of the processes of densification and pore closure in firn (compacted snow). Current firn densification models are based on a macroscopic description of the firn and rely on empirical laws and/or idealized geometries to obtain the equations governing the densification and pore closure. Here, we propose a physically-based methodology explicitly representing the porous structure and its evolution over time. In order to handle the complex geometry and topological changes that occur during firn densification, we rely on a Level-Set representation of the interface between the ice and the pores. Two mechanisms are considered for the displacement of the interface: (i) mass surface diffusion driven by local pore curvature and (ii) ice dislocation creep. For the latter, ice is modeled as a viscous material and the flow velocities are solutions of the Stokes equations. First applications show that the model is able to densify firn and split pores. Using the model in cold and arid conditions of the Antarctic plateau, we show that gas trapping models do not have to consider the reduced compressibility of closed pores compared to open pores in the deepest part of firns. Our results also suggest that the mechanism of curvature-driven surface diffusion does not result in pore splitting, and that ice creep has to be taken into account for pores to close. Future applications of this type of model could help quantify the evolution and closure of firn porous networks for various accumulation and temperature conditions. |
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1153 |
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2296-6463 |
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8268 |
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