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Tonya M. Burgers, Jean-Éric Tremblay, Brent G. T. Else, Tim N. Papakyriakou. (2020). Estimates of net community production from multiple approaches surrounding the spring ice-edge bloom in Baffin Bay (Vol. 8).
Abstract: Measurements of net community production (NCP) provide an upper constraint on the strength of the oceanic biological pump, the dominant mechanism for removing CO2 from the ocean surface and sequestering it at depth. In this investigation, our objectives were to describe the spatial and temporal variability of NCP associated with the spring ice-edge bloom in Baffin Bay and to identify the key environmental drivers controlling its variability. Using data collected between June 9 and July 10, 2016, we estimated NCP based on (1) underway measurements of surface water oxygen to argon ratios (O2:Ar), (2) underway measurements of the partial pressure of CO2, and (3) seasonal nitrate drawdown from discrete samples. These multiple approaches displayed high NCP (up to 5.7 mol C m–2) in eastern Baffin Bay, associated with modified Atlantic waters, and low NCP (<1 mol C m–2) in the presence of Arctic outflow waters in western Baffin Bay. Arctic outflow waters were characterized by low surface salinities and nitrate concentrations, suggesting that high freshwater content may have limited the nutrient availability of these waters. Different integration depths and timescales associated with each NCP approach were exploited to understand the temporal progression and succession of the bloom, revealing that the bloom was initiated under ice up to 15 days prior to ice retreat and that a large portion of NCP in eastern Baffin Bay (potentially up to 70%) was driven by primary production occurring below the surface-mixed layer.
Programme: 1164
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C Engrand, E Charon, H Le- Roux, M Marinova, J Duprat, E Dartois, B Guérin, J Rojas, L Delauche, M Godard, D Troadec. (2020). Evidence of irradiation in interplanetary space in minerals from an ultracarbonaceous Antarctic micrometeorites (UCAMM).
Abstract: Introduction: Ultracarbonaceous Antarctic Micrometeorites (UCAMMs) are dominated by N-rich polyaromatic organic matter exhibiting large D enrichments [1-5]. The high abundance of organic matter exhibiting large D enrichment suggests a cometary origin for UCAMMs [1-3]. Three kinds of organic matter are identified in UCAMMs, with different nitrogen abundances and highly variable concentrations of small (typically 30-500 nanometer) mineral aggregates embedded in the organic matter [5-8]. We focus here on a mineral assemblage embedded in one UCAMM that exhibits evidence of ion irradiation, to get insight on the formation and evolution of this cometary particle. Sample and methods: A fragment of UCAMM DC06-06-43 (hereafter DC06-43) was carbon coated, observed by SEM/EDX, and a 100 nm thick FIB section of this fragment was made at IEMN Lille. The size of the initial UCAMM before fragmentation was ~ 25 x 30 µm. After STXM-XANES analysis, the mineralogy of the sample was investigated by TEM at UMET Lille using a FEI Tecnai G2 20 at 200 kV and FEI TITAN Themis at 300 kV [9]. Results : TEM examination reveals a large assemblage of crystalline minerals at the center of the DC06-43 UCAMM fragment, surrounded by organic matter (Figure 1) [9]. The assemblage consists of µm-to subµm sized Mg-rich pyroxenes, a large “triskell”-shaped Fe-sulfide, a few Mg-rich olivines, and minor Si-Al-Carich amorphous pockets and Fe-Ni metal. About 28 crystalline pyroxenes are identified whereas only 5 olivine crystals are observed in the section. GEMS are present embedded in the organic matter, close to the crystalline assemblage. We identified irradiation features (rims and tracks) in pyroxene grains. No rims or tracks were found in olivine. We observed irradiated rims around six pyroxenes at the top of the section (Figure 1, light blue labels). One pyroxene shows a continuous irradiated rim (Figure 2 top). Rim thicknesses range from 20 to 100 nm, with an average of 60 ± 20 nm (1σ) (Figure 2 bottom). Fe-rich deposits are occasionally found on top of irradiated rims. EDX mappings and profiles show that the rims are strongly depleted in Mg (Figure 3). The average track density in pyroxene grains measured over an area of 4.5 x 10-8 cm 2 is 1.3 x 10 10 cm-2 with one value at 3.8 x 10 9 cm-2 , the other values ranging from 9.5 x 10 9 to 3.2 x 10 10 cm-2 (Figure 4). Irradiation track lengths
Programme: 1120
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Hila Levy, Steven R Fiddaman, Juliana A Vianna, Daly Noll, Gemma V Clucas, Jasmine K H Sidhu, Michael J Polito, Charles A Bost, Richard A Phillips, Sarah Crofts, Gary D Miller, Pierre Pistorius, Francesco Bonnadonna, Céline Le Bohec, Andrés Barbosa, Phil Trathan, Andrea Raya Rey, Laurent A F Frantz, Tom Hart, Adrian L Smit. (2020). Evidence of Pathogen-Induced Immunogenetic Selection across the Large Geographic Range of a Wild Seabird (Vol. 37). Bachelor's thesis, , .
Abstract: Over evolutionary time, pathogen challenge shapes the immune phenotype of the host to better respond to an incipient threat. The extent and direction of this selection pressure depend on the local pathogen composition, which is in turn determined by biotic and abiotic features of the environment. However, little is known about adaptation to local pathogen threats in wild animals. The Gentoo penguin (Pygoscelis papua) is a species complex that lends itself to the study of immune adaptation because of its circumpolar distribution over a large latitudinal range, with little or no admixture between different clades. In this study, we examine the diversity in a key family of innate immune genes—the Toll-like receptors (TLRs)—across the range of the Gentoo penguin. The three TLRs that we investigated present varying levels of diversity, with TLR4 and TLR5 greatly exceeding the diversity of TLR7. We present evidence of positive selection in TLR4 and TLR5, which points to pathogen-driven adaptation to the local pathogen milieu. Finally, we demonstrate that two positively selected cosegregating sites in TLR5 are sufficient to alter the responsiveness of the receptor to its bacterial ligand, flagellin. Taken together, these results suggest that Gentoo penguins have experienced distinct pathogen-driven selection pressures in different environments, which may be important given the role of the Gentoo penguin as a sentinel species in some of the world’s most rapidly changing environments.
Keywords: immunogenetics, positive selection, Toll-like receptors, pathogen-mediated selection, Antarctica and Southern Ocean, Gentoo penguin
Programme: 137,354
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Chelsea Ward. (2020). Examining the effect of experimentally induced stress and the stress response on eye region surface temperature in wild king penguins (Aptenodytes patagonicus) (supervisors P Bize and A Lewden).
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Martischang J-P. (2020). Exoplanètes : sélection de calibrateurs et ajustements de transits. Bachelor's thesis, , .
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Manrico Sebastiano, Frédéric Angelier, Pierre Blévin, Cécile Ribout, Kjetil Sagerup, Sébastien Descamps, Dorte Herzke, Børge Moe, Christophe Barbraud, Jan Ove Bustnes, Geir Wing Gabrielsen, Olivier Chastel. (2020). Exposure to PFAS is Associated with Telomere Length Dynamics and Demographic Responses of an Arctic Top Predator (Vol. 54).
Abstract: Environmental factors that can influence telomeres are diverse, but the association between telomeres and exposure to environmental contaminants is yet to be elucidated. To date, prior studies have focused on legacy persistent chlorinated pollutants (POPs), while the effects of poly- and perfluoroalkyl substances (PFAS) have been poorly documented. Here, we investigated the associations among PFAS congeners, absolute telomere length (cross-sectional approach), and telomere dynamics (rate of telomere length change over time, longitudinal approach) in one of the most contaminated arctic top predators, the glaucous gull Larus hyperboreus from Svalbard. We further estimated the effect of PFAS on apparent survival rates and re-sighting probabilities using a 10-year capture/recapture dataset (2010–2019). We found that birds exposed to higher concentrations of perfluorononadecanoate (PFNA) (median of 1565 pg/mL of ww in males and 1370 pg/mL of ww in females) and perfluorotetradecanoate (PFTeDA) (median of 370 pg/mL of ww in males and 210 pg/mL of ww in females) showed the slowest rate of telomere shortening. We also found that high blood concentrations of perfluorooctanoate (PFOA) (median of 120 pg/mL of ww in males and 150 pg/mL of ww in females) and perfluorohexanesulfonate (PFHxS) (median of 495 pg/mL of ww in males and 395 pg/mL of ww in females) were positively associated with higher re-sighting probabilities and apparent survival in males but not in females. Our work is the first to report an association between single PFAS compounds and telomeres, and the first to link PFAS exposure with survival probabilities, suggesting that the effect of PFAS exposure might be more tied to the type of compound rather than the total concentration of PFAS.
Programme: 330
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B. Lauer, R. Grandin, Y. Klinger. (2020). Fault Geometry and Slip Distribution of the 2013 Mw 7.7 Balochistan Earthquake From Inversions of SAR and Optical Data (Vol. 125).
Abstract: The 2013 Mw 7.7 Balochistan earthquake ruptured the Hoshab fault (Pakistan) over 200 km. It was dominated by left-lateral slip, with a secondary reverse component. By combining optical (SPOT 5 and Landsat 8) and radar satellite data (RADARSAT-2 and TerraSAR-X ScanSAR), we derive the 3-D coseismic displacement field and the slip distribution. Our modeling strategy involves two successive inversions allowing to explore first the fault geometry and then slip distribution. Following a statistical analysis of the coseismic surface trace, the fault is discretized into 16 segments. To determine the dip angle and down-dip width of the segments, we then perform a non-linear elastic inversion of the geodetic data set. Using output of this model, we prescribe the fault geometry and linearly invert for slip at depth with refined discretization. Results show a decrease of the fault dip, reaching 50° in the central part of the fault that structurally connects the two sub-vertical terminations dipping at >70°. The distribution of strike-slip forms a shallow continuous patch (0–8 km) that peaks at 12.7 m of slip near the epicenter. Reverse slip is distributed on several patches and becomes shallower near the southern termination, where it peaks at 5.7 m. Our model shows an absence of shallow slip deficit (SSD), as for other Mw 7.5 + strike-slip earthquakes elsewhere, hence suggesting that SSD is only found for lesser magnitude earthquakes. We speculate that moment magnitude is a key element in the occurrence of SSD.
Keywords: Balochistan earthquake earthquake rupture modeling earthquake source processes InSAR optical data shallow slip deficit
Programme: 133
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Rémi Bigonneau, Romain Bazire, Cédric Marteau, Christophe Barbraud, Joan Ferrer-Obiol, Karine Delord. (2020). First record of Black-winged Pratincole Glareola nordmanni for Amsterdam Island, Indian Ocean (Vol. 27). Bachelor's thesis, , .
Abstract: Première mention de la Glaréole à ailes noires Glareola nordmanni pour l’Île Amsterdam, Océan Indien. Une Glaréole à ailes noires Glareola nordmanni de premier hiver à été observée sur l’Île Amsterdam, dans le sud de l’Océan indien, les 12–16 novembre 2013. Il s’agît de la première donnée de cette espèce paléarctique pour l’île. Les mentions antérieures les plus proches proviennent de l’île d’Alphonse, aux Seychelles, à environ 4.200 km de l’Île Amsterdam.
Programme: 109
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Pauline Goulet, Christophe Guinet, Claudio Campagna, Julieta Campagna, Peter Lloyd Tyack, Mark Johnson. (2020). Flash and grab: deep-diving southern elephant seals trigger anti-predator flashes in bioluminescent prey (Vol. 223).
Abstract: Bioluminescence, which occurs in approximately 80% of the world's mesopelagic fauna, can take the form of a low-intensity continuous glow (e.g. for counter-illumination or signalling) or fast repetitions of brighter anti-predatory flashes. The southern elephant seal (SES) is a major consumer of mesopelagic organisms, in particular the abundant myctophid fish, yet the fine-scale relationship between this predator's foraging behaviour and bioluminescent prey remains poorly understood. We hypothesised that brief, intense light emissions should be closely connected with prey strikes when the seal is targeting bioluminescent prey that reacts by emitting anti-predator flashes. To test this, we developed a biologging device containing a fast-sampling light sensor together with location and movement sensors to measure simultaneously anti-predator bioluminescent emissions and the predator's attack motions with a 20 ms resolution. Tags were deployed on female SES breeding at Kerguelen Islands and Península Valdés, Argentina. In situ light levels in combination with duration of prey capture attempts indicated that seals were targeting a variety of prey types. For some individuals, bioluminescent flashes occurred in a large proportion of prey strikes, with the timing of flashes closely connected with the predator's attack motion, suggestive of anti-predator emissions. Marked differences across individuals and location indicate that SES do exploit bioluminescent organisms but the proportion of these in the diet varies widely with location. The combination of wideband light and acceleration data provides new insight into where and when different prey types are encountered and how effectively they might be captured.
Programme: 1201
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Vincent A. Viblanc, Quentin Schull, Antoine Stier, Laureline Durand, Emilie Lefol, Jean-Patrice Robin, Sandrine Zahn, Pierre Bize, François Criscuolo. (2020). Foster rather than biological parental telomere length predicts offspring survival and telomere length in king penguins.
Abstract: Because telomere length and dynamics relate to individual growth, reproductive investment and survival, telomeres have emerged as possible markers of individual quality. Here, we tested the hypothesis that, in species with parental care, parental telomere length can be a marker of parental quality that predicts offspring phenotype and survival. In king penguins (Aptenodytes patagonicus), we experimentally swapped the single egg of 66 breeding pairs just after egg laying to disentangle the contribution of prelaying parental quality (e.g., genetics, investment in the egg) and/or postlaying parental quality (e.g., incubation, postnatal feeding rate) on offspring growth, telomere length and survival. Parental quality was estimated through the joint effects of biological and foster parent telomere length on offspring traits, both soon after hatching (day 10) and at the end of the prewinter growth period (day 105). We expected that offspring traits would be mostly related to the telomere lengths (i.e., quality) of biological parents at day 10 and to the telomere lengths of foster parents at day 105. Results show that chick survival up to 10 days was negatively related to biological fathers’ telomere length, whereas survival up to 105 days was positively related to foster fathers’ telomere lengths. Chick growth was not related to either biological or foster parents’ telomere length. Chick telomere length was positively related to foster mothers’ telomere length at both 10 and 105 days. Overall, our study shows that, in a species with biparental care, parents’ telomere length is foremost a proxy of postlaying parental care quality, supporting the “telomere – parental quality hypothesis.”
Keywords: gene and early life environmental effects growth penguins reproduction investment telomere
Programme: 119
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