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Yushiro Fujii, Kenji Satake, Shingo Watada, Tung-Cheng Ho. (2021). Re-examination of Slip Distribution of the 2004 Sumatra–Andaman Earthquake (Mw 9.2) by the Inversion of Tsunami Data Using Green’s Functions Corrected for Compressible Seawater Over the Elastic Earth (Vol. 178).
Abstract: We re-examined the slip distribution on faults of the 2004 Sumatra–Andaman (M 9.1 according to USGS) earthquake by the inversion of tsunami data with phase-corrected Green’s functions applied to linear long waves. The correction accounts for the effects of compressibility of seawater, elasticity of solid earth, and gravitational potential variation associated with the motion of mass to reproduce the delayed arrivals and the reversed phase of the first tsunami waves. We used sea surface height (SSH) data from satellite altimetry (SA) measurements along five tracks, and the tsunami waveforms recorded at tide gauges (TGs) and ocean bottom pressure gauges (OBPGs) in and around the Indian Ocean. The inversion results for both data sets for different rupture velocities (Vr) show that the reproducibility of the spatiotemporal SSHs and tsunami waveforms is improved by the phase corrections, although the effects are not so significant within the Indian Ocean. The best slip distribution model from joint inversion of SA, TG and OBPG data with Vr of 1.3 km/s shows the largest slips of 16–25 m off Sumatra Island, large slips of 2–11 m off the Nicobar Islands, and moderate slips of 2–6 m in the Andaman Islands. The inversion results reproduce the far-field tsunami waveforms well at distant stations even more than 13,000–25,000 km from the epicenter. The total source length is about 1400 km and the seismic moment is Mw 9.2, longer and larger than that of our previous estimates based on TG records.
Keywords: 2004 Sumatra–Andaman earthquake far-field tsunami waveform phase-corrected Green’s function slip distribution tsunami data inversion
Programme: 688
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Sarah Leclaire, Vincent Bourret, Maxime Pineaux, Pierrick Blanchard, Etienne Danchin, Scott A. Hatch. (2019). Red coloration varies with dietary carotenoid access and nutritional condition in kittiwakes (Vol. 222).
Abstract: Carotenoid-based ornaments are common signaling features in animals. Although the mechanisms that link color-based signals to individual condition is key to understanding the evolution and function of these ornaments, they are most often poorly known. Several hypotheses have been posited. They include: (i) the role of foraging abilities on carotenoid acquisition and thereby carotenoid-based ornaments, and (ii) the role of internal processes linked to individual quality on the allocation and conversion of carotenoids in integuments. Here, we tested the influence of dietary carotenoid access versus internal process on gape coloration in black-legged kittiwakes (Rissa tridactyla). This seabird displays a vibrant red gape, whose coloration varies with individual quality in males and is due to the deposition of red ketocarotenoids, such as astaxanthin. We decreased hydroxycarotenoid and ketocarotenoid levels in plasma, but increased efficiency in internal processes linked to nutritional condition, by supplementing breeding males with capelin, a natural energy-rich fish prey. We found that, despite having lower carotenoid levels in plasma, supplemented birds developed redder coloration than control birds, but only in the year when dietary levels of astaxanthin in the natural diet were low. In contrast, in the astaxanthin-rich year, supplemented males had a less-red gape than unsupplemented birds. These results suggest that inter-individual differences in internal processes may be sufficient to maintain the honesty of gape coloration under conditions of low dietary astaxanthin levels. Nonetheless, when inter-individual variations in dietary astaxanthin levels are elevated (such as in the crustacean-rich year), carotenoid access seems a more limiting factor to the expression of gape coloration than internal processes. Therefore, our study revealed a complex mechanism of gape color production in kittiwakes, and suggests that the main factor maintaining the condition dependency of this ornaments may vary with environmental conditions and diet composition.
Programme: 1162
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Pierre Stephan, Lancelot Massé, David Dider, Ronan Autret, Antoine Soloy, Serge Suanez. (2022). Pluri-annual morphological and sedimentological changes of the Valahnúkur boulder barrier, SW Iceland.
Abstract:
While recent studies highlighted the great mobility of boulder beaches related to the impact of storm waves, numerous researches are still needed to better understand the morphodynamic of coastal boulder accumulations. This paper provides original data about pluri-annual morphological and sedimentological changes, as well as storm-induced geomorphic processes and their impact on the Valahnúkur boulder barrier, in the south-west of Iceland. First described by Etienne & Paris (2010), this massive accumulation of boulders shows numerous evidences of coastal barrier flooding and intense boulder mobility. Between May 2015 and May 2021, a topo-morphological survey was undertaken to analyze and quantify both cross-shore and longshore morphosedimentary processes of the Valahnúkur boulder barrier and surrounding areas. Annual campaigns of UAV (Unmanned Aerial Vehicle) flights were conducted in order to produce a set of Digital Elevation Models (DEMs) and Orthophotographs using Structure-from-Motion photogrammetry. DEMs were compared to deduce the morphological changes. Orthophotographs were analyzed from a deep learning-based method to estimate the changes in the spatial distribution of boulder sizes. Hydrodynamic conditions were reconstructed using wave buoy and tide gauge measurements. Wave runup were calibrated from the analysis of a wave/swash motion data set acquired by video monitoring related to different hydrodynamic conditions. The chronology of extreme water levels has been reconstructed on this high refective beach to estimate the elevation of the wave action during the survey period. From the sediment budget calculation, a significant northward longshore drift of around 1000 m3/a is highlighted on the beachface. The ridge and back-barrier areas were dominated by accretion related to cross-shore boulder transport from the beach. The volume of transported boulders is highly variable according to hydrodynamic conditions. Although the morphogenic impact of winter storms is difficult to assess, the observed morphological changes suggest processes dominated by swash, overtopping and overwash. The boulder size analysis highlights a link between the boulders mass and their movement landward. Video monitoring indicates that the amplitude of the swash is quite similar whether the hydrodynamic conditions are normal or energetic. The high porosity of the barrier appears to be a key factor in the dissipation of wave energy. Programme: 1216
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Georg Lackner, Florent Domine, Daniel F. Nadeau, Annie-Claude Parent, François Anctil, Matthieu Lafaysse, Marie Dumont. (2022). On the energy budget of a low-Arctic snowpack (Vol. 16).
Abstract:
Abstract. Arctic landscapes are covered in snow for at least 6 months of the year. The energy balance of the snow cover plays a key role in these environments, influencing the surface albedo, the thermal regime of the permafrost, and other factors. Our goal is to quantify all major heat fluxes above, within, and below a low-Arctic snowpack at a shrub tundra site on the east coast of Hudson Bay in eastern Canada. The study is based on observations from a flux tower that uses the eddy covariance approach and from profiles of temperature and thermal conductivity in the snow and soil. Additionally, we compared the observations with simulations produced using the Crocus snow model. We found that radiative losses due to negative longwave radiation are mostly counterbalanced by the sensible heat flux, whereas the latent heat flux is minimal. At the snow surface, the heat flux into the snow is similar in magnitude to the sensible heat flux. Because the snow cover stores very little heat, the majority of the upward heat flux in the snow is used to cool the soil. Overall, the model was able to reproduce the observed energy balance, but due to the effects of atmospheric stratification, it showed some deficiencies when simulating turbulent heat fluxes at an hourly timescale. Programme: 1042
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Tignat-Perrier, R., Vogel, T. M., Técher, N., Larose, C., and Dommergue, A. (2022). Microorganisms Floating Through the Air.
Abstract: Would you believe us if we told you that, when you breathe in, you inhale thousands of microorganisms with every breath. Although this might sound scary, be assured that they are safe for your health. These airborne microorganisms, too small to see with the naked eye, consist of many different species. Who are they? Where do they come from? What do they do in the air? These are some of the questions that we answer in this article, although many questions about airborne microorganisms remain to be explored.
Programme: 1028
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Niels Martin Schmidt, Tomas Roslin, Lars Holst Hansen, Olivier Gilg, Johannes Lang, Benoit Sittler, Jannik Hansen, Loïc Bollache, Eero Vesterinen. (2022). Spatio-temporal patterns in arctic fox (Vulpes alopex) diets revealed by molecular analysis of scats from Northeast Greenland (Vol. 32).
Abstract: The arctic fox (Vulpes lagopus) is endemic to the Arctic where it holds a central position in the trophic interactions. The diet of the species has previously been described as being highly flexible, but whether this flexibility is a constant trait through time, or merely reflects fast temporal changes in abundance among prey taxa, has so far been poorly resolved. Using molecular analyses of arctic fox scats from Northeast Greenland, we first examined the temporal dynamics of arctic fox diets during the short snow-free season, and then examined whether local food availability at different sites affected arctic fox dependence on lemmings. Arctic fox diets included most terrestrial vertebrate species found in the region, and exhibited substantial temporal changes, generally reflecting the dynamic changes in prey availability from late winter through autumn. This dietary flexibility was also reflected geographically, with arctic foxes consuming a variety of local prey (mainly waterfowl and lemmings) in summer. Moreover, the dietary response of arctic foxes to changes in lemming abundance depended on access to non-lemming prey. Based on these findings, we discuss whether varying degrees of lemming-dependency, combined with geographical differences in winter food availability, may explain previously published differences in arctic fox breeding patterns in high arctic Greenland.
Keywords: Greenland Metabarcoding Predation Trophic interactions Tundra
Programme: 1036
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Hassen Allegue, Christophe Guinet, Samantha C. Patrick, Mark A. Hindell, Clive R. McMahon, Denis Réale. (2022). Sex, body size, and boldness shape the seasonal foraging habitat selection in southern elephant seals (Vol. 12). Bachelor's thesis, , .
Abstract: Selecting foraging habitat is a fundamental behavior in the life of organisms as it directly links resource acquisition to fitness. Differences in habitat selection among individuals may arise from several intrinsic and extrinsic factors, and yet, their interaction has been given little attention in the study of wild populations. We combine sex, body size, and boldness to explain individual differences in the seasonal foraging habitat selection of southern elephant seals (Mirounga leonina) from the Kerguelen Archipelago. We hypothesize that habitat selection is linked to the trade-off between resource acquisition and risk, and that individuals differ in their position along this trade-off because of differences in reproductive strategies, life stages, and metabolic requirements. Before the post-molt foraging trip, we used a novel object approach test to quantify the boldness of 28 subadult and adult females and 42 subadult males and equipped them with data loggers to track their movements at sea. Subadult males selected neritic and oceanic habitats, whereas females mostly selected less productive oceanic habitats. Both sexes showed a seasonal shift from Antarctic habitats in the south in the summer to the free of ice subantarctic and subtropical habitats in the north in the winter. Males avoided oceanic habitats and selected more productive neritic and Antarctic habitats with body size mostly in the winter. Bolder males selected northern warmer waters in winter, while shyer ones selected the Kerguelen plateau and southern colder oceanic waters. Bolder females selected the Kerguelen plateau in the summer when prey profitability is assumed to be the highest. This study not only provides new insights into the spatiotemporal foraging ecology of elephant seals in relation to personality but also emphasizes the relevance of combining several intrinsic and extrinsic factors in understanding among-individual variation in space use essential in wildlife management and conservation.
Keywords: benefit–cost trade-off biologging habitat selection Mirounga leonina personality
Programme: 109,1201
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Sophia Ferchiou, France Caza, Richard Villemur, Jacques Labonne, Yves St-Pierre. (2023). Skin and Blood Microbial Signatures of Sedentary and Migratory Trout (Salmo trutta) of the Kerguelen Islands (Vol. 8).
Abstract: Our understanding of how microbiome signatures are modulated in wild fish populations remains poorly developed and has, until now, mostly been inferred from studies in commercial and farmed fish populations. Here, for the first time, we have studied changes in the skin and blood microbiomes of the Salmo trutta population of the volcanic Kerguelen archipelago located at the northern limit of the Antarctic Ocean. The Kerguelen Islands present a natural framework of population expansion and reveal a likely situation representing further climate change in distribution areas. Our results showed that S. trutta of the Kerguelen Islands has a microbiome signature distinct from those of salmonids of the Northern Hemisphere. Our study also revealed that the skin and blood microbiomes differ between sedentary and migratory S. trutta. While 18 phyla were shared between both groups of trout, independent of the compartment, 6 phyla were unique to migratory trout. Further analyses showed that microbiome signatures undergo significant site-specific variations that correlate, in some cases, with the peculiarity of specific ecosystems. Our study also revealed the presence of potential pathogens at particular sites and the impact of abiotic factors on the microbiome, most notably due to the volcanic nature of the environment. This study contributes to a better understanding of the factors that modulate the microbiome signatures of migratory and sedentary fish populations. It will also help to better monitor the impacts of climate change on the colonization process in the sub-Antarctic region.
Keywords: Salmo trutta 16S rRNA blood microbiome fish Kerguelen Islands migration skin microbiome
Programme: 1041
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Emeline Charbonnel, Claire Daguin-Thiébaut, Lucille Caradec, Eléonore Moittié, Olivier Gilg, Maria V. Gavrilo, Hallvard Strøm, Mark L. Mallory, R. I. Guy Morrison, H. Grant Gilchrist, Raphael Leblois, Camille Roux, Jonathan M. Yearsley, Glenn Yannic, Thomas Broquet. (2022). Searching for genetic evidence of demographic decline in an arctic seabird: beware of overlapping generations (Vol. 128).
Abstract: Genetic data are useful for detecting sudden population declines in species that are difficult to study in the field. Yet this indirect approach has its own drawbacks, including population structure, mutation patterns, and generation overlap. The ivory gull (Pagophila eburnea), a long-lived Arctic seabird, is currently suffering from rapid alteration of its primary habitat (i.e., sea ice), and dramatic climatic events affecting reproduction and recruitment. However, ivory gulls live in remote areas, and it is difficult to assess the population trend of the species across its distribution. Here we present complementary microsatellite- and SNP-based genetic analyses to test a recent bottleneck genetic signal in ivory gulls over a large portion of their distribution. With attention to the potential effects of population structure, mutation patterns, and sample size, we found no significant signatures of population decline worldwide. At a finer scale, we found a significant bottleneck signal at one location in Canada. These results were compared with predictions from simulations showing how generation time and generation overlap can delay and reduce the bottleneck microsatellite heterozygosity excess signal. The consistency of the results obtained with independent methods strongly indicates that the species shows no genetic evidence of an overall decline in population size. However, drawing conclusions related to the species’ population trends will require a better understanding of the effect of age structure in long-lived species. In addition, estimates of the effective global population size of ivory gulls were surprisingly low (~1000 ind.), suggesting that the evolutionary potential of the species is not assured.
Keywords: Conservation biology Population genetics
Programme: 1210
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Tracey L. Hammer, Pierre Bize, Claire Saraux, Benoit Gineste, Jean-Patrice Robin, René Groscolas, Vincent A. Viblanc. (2022). Repeatability of alert and flight initiation distances in king penguins: Effects of colony, approach speed, and weather (Vol. 128).
Abstract: Alert distance (AD) and flight initiation distance (FID) are popular measures used to explore the reaction of prey to approaching predators, and thus the economics underlying optimal escape strategies. AD likely mirrors the effort invested into vigilance, while FID provides an estimate of the perceived risk of an approaching threat. Although individual variation in AD and FID is influenced by environmental factors such as variation in predation pressure and human disturbance, the repeatabilities of these traits (especially AD), and therefore their designation as personality traits, remain under-investigated. Here, we studied the repeatability of AD, FID, and the decision to flee in a flightless, ground-breeding seabird, the king penguin (Aptenodytes patagonicus). A single experimenter approached three times over three consecutive days 47 incubating king penguins from two different colonies with varying human disturbance levels. We explored the effects of weather, time of day, and approach speed of the experimenter on these behaviors. Weather had an effect on all three behaviors. In warm, sunny weather AD increased. In rainy, windy weather birds were more likely to flee, but waited longer before initiating flight. Faster approach speeds between AD and FID increased FID. Weather conditions and speed of approach affected repeatability estimates, highlighting the need to consider external sources of variation when refining such estimates. FID and the decision to flee were significantly and moderately repeatable (r = 0.26 and 0.57, respectively), while AD was not. There was no evidence of behavioral habituation or sensitization in either colony.
Keywords: Aptenodytes patagonicus human disturbance optimal escape decisions personality predation risk
Programme: 119
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