Stier A, Lewden A, Ruuskanen S, Noiret A, Angelier F, Robin Jp, Bize P, Raclot T, Roussel D, Ropert-coudert Y, Viblanc Va. (2021). HotPenguin : cool in the water, too hot on land ? Risks and consequences of heat stress in penguins facing climate change.
Abstract: Animals from polar regions have evolved highly specialized adaptations to cope with cold climates, which put them at risk regarding the current rapid climate change. This is especially true for penguins who live most of the year in cold water, but breed on land in the spring/summer. Penguins are thereby likely to be threatened by periods of unusually warm temperatures on land. While heat stress is increasingly studied in warm regions, few studies have investigated whether heat stress could occur in polar regions, and to what extent it could affect individual health and reproduction. My aim is to fill this knowledge gap by leading a collaborative research project taking an integrative approach, from animal behavior to the sub-cellular level. This project aims at helping to better predict how penguin populations will respond to future climate change, and raise awareness of scientists, stakeholders and the general public towards an under-appreciated risk of climate change in polar regions.
Programme: 119
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Sindre H. Eldøy, Jan G. Davidsen, Matthias Vignon, Michael Power. (2021). The biology and feeding ecology of Arctic charr in the Kerguelen Islands (Vol. 98).
Abstract: Subsequent to their introduction in the 1950s, Arctic charr Salvelinus alpinus have been able to establish a self-sustaining population that has adapted to the unique conditions of the sub-Antarctic Kerguelen Islands. Here, 48 individuals (198–415 mm) were caught with gillnets and their basic biology and feeding ecology were examined using stable isotope analysis. The Lac des Fougères population split use of littoral and pelagic resources evenly, although larger fish relied more heavily on littoral production and appear to follow the size-dependent life history habitat template seen in many Scandinavian lakes where smaller sized individuals occupy the pelagic zone and larger individuals dominate the littoral habitat. In Kerguelen, Arctic charr mature at the same ages (5.6 years) as Arctic charr in both sub-Arctic and Arctic lakes. Although mortality was average in comparison to comparator sub-Arctic lakes, it was high in comparison to Arctic lakes. Maximal age (>7+) was at the lower end of the range typically seen in sub-Arctic lakes. Although they inhabit a resource-poor environment, Kerguelen Arctic charr showed no evidence of cannibalism. Thus, while Arctic charr can survive and reproduce in the relatively unproductive Kerguelen lake environments, survival and growth nevertheless appear to be traded off against survival and longevity. The uniqueness of the population location and the recency of its introduction suggest that further monitoring of the population has the potential to yield valuable insights into both the adaptability of the species and its likely responses to ongoing large-scale environmental change as represented by climate change.
Programme: 1041
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Jacques Labonne, Aurélie Manicki, Louise Chevalier, Marin Tétillon, François Guéraud, Andrew P. Hendry. (2021). Using Reciprocal Transplants to Assess Local Adaptation, Genetic Rescue, and Sexual Selection in Newly Established Populations (Vol. 12).
Abstract: Small populations establishing on colonization fronts have to adapt to novel environments with limited genetic variation. The pace at which they can adapt, and the influence of genetic variation on their success, are key questions for understanding intraspecific diversity. To investigate these topics, we performed a reciprocal transplant experiment between two recently founded populations of brown trout in the sub-Antarctic Kerguelen Islands. Using individual tagging and genetic assignment methods, we tracked the fitness of local and foreign individuals, as well as the fitness of their offspring over two generations. In both populations, although not to the same extent, gene flow occurred between local and foreign gene pools. In both cases, however, we failed to detect obvious footprints of local adaptation (which should limit gene flow) and only weak support for genetic rescue (which should enhance gene flow). In the population where gene flow from foreign individuals was low, no clear differences were observed between the fitness of local, foreign, and F1 hybrid individuals. In the population where gene flow was high, foreign individuals were successful due to high mating success rather than high survival, and F1 hybrids had the same fitness as pure local offspring. These results suggest the importance of considering sexual selection, rather than just local adaptation and genetic rescue, when evaluating the determinants of success in small and recently founded populations.
Keywords: gene flow genetic rescue local adaptation mating success small population
Programme: 1041
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Jan Grimsrud Davidsen, Xavier Bordeleau, Sindre Håvarstein Eldøy, Frederick Whoriskey, Michael Power, Glenn T. Crossin, Colin Buhariwalla, Philippe Gaudin. (2021). Marine habitat use and feeding ecology of introduced anadromous brown trout at the colonization front of the sub-Antarctic Kerguelen archipelago (Vol. 11).
Abstract: In 1954, brown trout were introduced to the Kerguelen archipelago (49°S, 70°E), a pristine, sub-Antarctic environment previously devoid of native freshwater fishes. Trout began spreading rapidly via coastal waters to colonize adjacent watersheds, however, recent and unexpectedly the spread has slowed. To better understand the ecology of the brown trout here, and why their expansion has slowed, we documented the marine habitat use, foraging ecology, and environmental conditions experienced over one year by 50 acoustically tagged individuals at the colonization front. Trout mainly utilized the marine habitat proximate to their tagging site, ranging no further than 7 km and not entering any uncolonized watersheds. Nutritional indicators showed that trout were in good condition at the time of tagging. Stomach contents and isotope signatures in muscle of additional trout revealed a diet of amphipods (68%), fish (23%), isopods (6%), and zooplankton (6%). The small migration distances observed, presence of suitable habitat, and rich local foraging opportunities suggest that trout can achieve their resource needs close to their home rivers. This may explain why the expansion of brown trout at Kerguelen has slowed.
Keywords: Animal migration Behavioural ecology Ecology Stable isotope analysis
Programme: 1041
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Joanna Charton, Vincent Jomelli, Irene Schimmelpfennig, Deborah Verfaillie, Vincent Favier, Fatima Mokadem, Adrien Gilbert, Fanny Brun, Georges Aumaître, Didier L. Bourlès, Karim Keddadouche. (2021). A debris-covered glacier at Kerguelen (49°S, 69°E) over the past 15 000 years (Vol. 33).
Abstract: Debris-covered glaciers constitute a large part of the world's cryosphere. However, little is known about their long-term response to multi-millennial climate variability, in particular in the Southern Hemisphere. Here, we provide first insights into the response of a debris-covered glacier to multi-millennial climate variability in the sub-Antarctic Kerguelen Archipelago, which can be compared to that of recently investigated debris-free glaciers. We focus on the Gentil Glacier and present 13 new 36Cl cosmic-ray exposure ages from moraine boulders. The Gentil Glacier experienced at least two glacial advances: the first one during the Late Glacial (19.0–11.6 ka) at ~14.3 ka and the second one during the Late Holocene at ~2.6 ka. Both debris-covered and debris-free glaciers advanced broadly synchronously during the Late Glacial, most probably during the Antarctic Cold Reversal event (14.5–12.9 ka). This suggests that both glacier types at Kerguelen were sensitive to abrupt temperature changes recorded in Antarctic ice cores, associated with increased moisture. However, during the Late Holocene, the advance at ~2.6 ka was not observed in other glaciers and seems to be an original feature of the debris-covered Gentil Glacier, related to either distinct dynamics or to distinct sensitivity to precipitation changes.
Keywords: Antarctic Cold Reversal glacier fluctuations Holocene in situ cosmogenic chlorine-36 dating palaeoclimate sub-Antarctic
Programme: 1048
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Deborah Verfaillie, Joanna Charton, Irene Schimmelpfennig, Zoe Stroebele, Vincent Jomelli, François Bétard, Vincent Favier, Julien Cavero, Etienne Berthier, Hugues Goosse, Vincent Rinterknecht, Claude Legentil, Raphaelle Charrassin, Georges Aumaître, Didier L. Bourlès, Karim Keddadouche. (2021). Evolution of the Cook Ice Cap (Kerguelen Islands) between the last centuries and 2100 ce based on cosmogenic dating and glacio-climatic modelling (Vol. 33).
Abstract: The Cook Ice Cap (CIC) on the sub-Antarctic Kerguelen Islands recently experienced extremely negative surface mass balance. Further deglaciation could have important impacts on endemic and invasive fauna and flora. To put this exceptional glacier evolution into a multi-centennial-scale context, we refined the evolution of the CIC over the last millennium, investigated the associated climate conditions and explored its potential evolution by 2100 ce. A glaciological model, constrained by cosmic ray exposure dating of moraines, historical documents and recent direct mass balance observations, was used to simulate the ice-cap extents during different phases of advance and retreat between the last millennium and 2100 ce. Cosmogenic dating suggests glacial advance around the early Little Ice Age (LIA), consistent with findings from other sub-Antarctic studies, and the rather cold and humid conditions brought about by the negative phase of the Southern Annular Mode (SAM). This study contributes to our currently limited understanding of palaeoclimate for the early LIA in the southern Indian Ocean. Glaciological modelling and observations confirm the recent decrease in CIC extent linked to the intensification of the SAM. Although affected by large uncertainties, future simulations suggest a complete disappearance of CIC by the end of the century.
Keywords: degree-day glaciological model future projections glacial fluctuations in situ cosmogenic chlorine-36 dating moraines sub-Antarctic islands
Programme: 1048
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Rebekah I. Dawson, Chelsea X. Huang, Rafael Brahm, Karen A. Collins, Melissa J. Hobson, Andrés Jordán, Jiayin Dong, Judith Korth, Trifon Trifonov, Lyu Abe, Abdelkrim Agabi, Ivan Bruni, R. Paul Butler, Mauro Barbieri, Kevin I. Collins, Dennis M. Conti, Jeffrey D. Crane, Nicolas Crouzet, Georgina Dransfield, Phil Evans, Néstor Espinoza, Tianjun Gan, Tristan Guillot, Thomas Henning, Jack J. Lissauer, Eric L. N. Jensen, Wenceslas Marie Sainte, Djamel Mékarnia, Gordon Myers, Sangeetha Nandakumar, Howard M. Relles, Paula Sarkis, Pascal Torres, Stephen Shectman, François-Xavier Schmider, Avi Shporer, Chris Stockdale, Johanna Teske, Amaury H. M. J. Triaud, Sharon Xuesong Wang, Carl Ziegler, G. Ricker, R. Vanderspek, David W. Latham, S. Seager, J. Winn, Jon M. Jenkins, L. G. Bouma, Jennifer A. Burt, David Charbonneau, Alan M. Levine, Scott McDermott, Brian McLean, Mark E. Rose, Andrew Vanderburg, Bill Wohler. (2021). Precise Transit and Radial-velocity Characterization of a Resonant Pair: The Warm Jupiter TOI-216c and Eccentric Warm Neptune TOI-216b (Vol. 161).
Abstract: TOI-216 hosts a pair of warm, large exoplanets discovered by the TESS mission. These planets were found to be in or near the 2:1 resonance, and both of them exhibit transit timing variations (TTVs). Precise characterization of the planets’ masses and radii, orbital properties, and resonant behavior can test theories for the origins of planets orbiting close to their stars. Previous characterization of the system using the first six sectors of TESS data suffered from a degeneracy between planet mass and orbital eccentricity. Radial-velocity measurements using HARPS, FEROS, and the Planet Finder Spectrograph break that degeneracy, and an expanded TTV baseline from TESS and an ongoing ground-based transit observing campaign increase the precision of the mass and eccentricity measurements. We determine that TOI-216c is a warm Jupiter, TOI-216b is an eccentric warm Neptune, and that they librate in 2:1 resonance with a moderate libration amplitude of deg, a small but significant free eccentricity of for TOI-216b, and a small but significant mutual inclination of 1.°2–3.°9 (95% confidence interval). The libration amplitude, free eccentricity, and mutual inclination imply a disturbance of TOI-216b before or after resonance capture, perhaps by an undetected third planet.
Programme: 1066
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M. A. Kenworthy, S. N. Mellon, J. I. Bailey, R. Stuik, P. Dorval, G. J. J. Talens, S. R. Crawford, E. E. Mamajek, I. Laginja, M. Ireland, B. Lomberg, R. B. Kuhn, I. Snellen, K. Zwintz, R. Kuschnig, G. M. Kennedy, L. Abe, A. Agabi, D. Mekarnia, T. Guillot, F. Schmider, P. Stee, Y. de Pra, M. Buttu, N. Crouzet, P. Kalas, J. J. Wang, K. Stevenson, E. de Mooij, A.-M. Lagrange, S. Lacour, A. Lecavelier des Etangs, M. Nowak, P. A. Strøm, Z. Hui, L. Wang. (2021). The β Pictoris b Hill sphere transit campaign – I. Photometric limits to dust and rings (Vol. 648).
Abstract: Aims. Photometric monitoring of β Pic in 1981 showed anomalous fluctuations of up to 4% over several days, consistent with foreground material transiting the stellar disk. The subsequent discovery of the gas giant planet β Pic b and the predicted transit of its Hill sphere to within a 0.1 au projected separation of the planet provided an opportunity to search for the transit of a circumplanetary disk (CPD) in this 21 ± 4 Myr-old planetary system. We aim to detect, or put an upper limit on, the density and nature of the material in the circumplanetary environment of the planet via the continuous photometric monitoring of the Hill sphere transit that occurred in 2017 and 2018.Methods. Continuous broadband photometric monitoring of β Pic requires ground-based observatories at multiple longitudes to provide redundancy and to provide triggers for rapid spectroscopic follow-up. These include the dedicated β Pic monitoring bRing observatories in Sutherland and Siding Springs, the ASTEP400 telescope at Concordia, and the space observatories BRITE and the Hubble Space Telescope (HST). We search the combined light curves for evidence of short-period transient events caused by rings as well as for longer-term photometric variability due to diffuse circumplanetary material.Results. We find no photometric event that matches with the event seen in November 1981, and there is no systematic photometric dimming of the star as a function of the Hill sphere radius.Conclusions. We conclude that the 1981 event was not caused by the transit of a CPD around β Pic b. The upper limit on the long-term variability of β Pic places an upper limit of 1.8 × 1022 g of dust within the Hill sphere (comparable to the ~100 km radius asteroid 16 Psyche). Circumplanetary material is either condensed into a disk that does not transit β Pic, condensed into a disk with moons that has an obliquity that does not intersect with the path of β Pic behind the Hill sphere, or is below our detection threshold. This is the first time that a dedicated international campaign has mapped the Hill sphere transit of an extrasolar gas giant planet at 10 au.
Programme: 1066
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Jennifer A. Burt, Diana Dragomir, Paul Mollière, Allison Youngblood, Antonio García Muñoz, John McCann, Laura Kreidberg, Chelsea X. Huang, Karen A. Collins, Jason D. Eastman, Lyu Abe, Jose M. Almenara, Ian J. M. Crossfield, Carl Ziegler, Joseph E. Rodriguez, Eric E. Mamajek, Keivan G. Stassun, Samuel P. Halverson, Steven Villanueva, R. Paul Butler, Sharon Xuesong Wang, Richard P. Schwarz, George R. Ricker, Roland Vanderspek, David W. Latham, S. Seager, Joshua N. Winn, Jon M. Jenkins, Abdelkrim Agabi, Xavier Bonfils, David Ciardi, Marion Cointepas, Jeffrey D. Crane, Nicolas Crouzet, Georgina Dransfield, Fabo Feng, Elise Furlan, Tristan Guillot, Arvind F. Gupta, Steve B. Howell, Eric L. N. Jensen, Nicholas Law, Andrew W. Mann, Wenceslas Marie-Sainte, Rachel A. Matson, Elisabeth C. Matthews, Djamel Mékarnia, Joshua Pepper, Nic Scott, Stephen A. Shectman, Joshua E. Schlieder, François-Xavier Schmider, Daniel J. Stevens, Johanna K. Teske, Amaury H. M. J. Triaud, David Charbonneau, Zachory K. Berta-Thompson, Christopher J. Burke, Tansu Daylan, Thomas Barclay, Bill Wohler, C. E. Brasseur. (2021). TOI-1231 b: A Temperate, Neptune-sized Planet Transiting the Nearby M3 Dwarf NLTT 24399 (Vol. 162).
Abstract: We report the discovery of a transiting, temperate, Neptune-sized exoplanet orbiting the nearby (d = 27.5 pc), M3V star TOI-1231 (NLTT 24399, L 248-27, 2MASS J10265947-5228099). The planet was detected using photometric data from the Transiting Exoplanet Survey Satellite and followed up with observations from the Las Cumbres Observatory and the Antarctica Search for Transiting ExoPlanets program. Combining the photometric data sets, we find that the newly discovered planet has a radius of and an orbital period of 24.246 days. Radial velocity measurements obtained with the Planet Finder Spectrograph on the Magellan Clay telescope confirm the existence of the planet and lead to a mass measurement of 15.5 ± 3.3 M ⊕. With an equilibrium temperature of just 330 K, TOI-1231 b is one of the coolest small planets accessible for atmospheric studies thus far, and its host star’s bright near-infrared brightness (J = 8.88, K s = 8.07) makes it an exciting target for the Hubble Space Telescope and the James Webb Space Telescope. Future atmospheric observations would enable the first comparative planetology efforts in the 250–350 K temperature regime via comparisons with K2-18 b. Furthermore, TOI-1231's high systemic radial velocity (70.5 km s−1) may allow for the detection of low-velocity hydrogen atoms escaping the planet by Doppler, shifting the H i Lyα stellar emission away from the geocoronal and interstellar medium absorption features.
Programme: 1066
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Yves Cherel. (2021). ?Mastigoteuthis B Clarke, 1980, is a junior synonym of Asperoteuthis acanthoderma (Lu, 1977) (Cephalopoda, Oegopsida, Chiroteuthidae), a rare cosmopolitan deep-sea squid (Vol. 51).
Abstract: The present work resolved the long-standing taxonomic problem associated with the enigmatic ?Mastigoteuthis B Clarke, 1980, by demonstrating that these lower beaks correspond to those of the large deep-sea chiroteuthid Asperoteuthis acanthoderma (Lu, 1977). A review of the existing literature listed 22 specimens of A. acanthoderma, but synonymizing ?Mastigoteuthis B with A. acanthoderma increased 14 times the species record worldwide. Pooling the data from both specimens and beaks (a total of 329 individuals) indicates that the species has a circumglobal distribution, since it occurs in tropical and subtropical waters of the Atlantic, Indian and Pacific Oceans. The synonymization also highlights trophic relationships of the species as a prey of top marine predators. Lower beaks of A. acanthoderma were mostly found in stomachs of sperm whales, but a few beaks were also recorded from stomach contents of sharks, swordfish and the wandering albatross.
Programme: 109
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