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Author |
Eugénie Tessier, Charles-André Bost |
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Title |
Behavioural adjustments during foraging in two diving seabirds: king and macaroni penguins |
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Journal |
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Year |
2020 |
Publication |
Marine Biology |
Abbreviated Journal |
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Volume |
167 |
Issue  |
9 |
Pages |
138 |
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Abstract |
Optimal foraging theory predicts that diving predators should maximise their energy intake while minimizing the costs of their foraging activities at depth. This hypothesis was tested in two breath-hold divers that foraged in the pelagic waters off Kerguelen Island, southern Indian Ocean. Macaroni penguins (Eudyptes chrysolophus) feed predominately on crustaceans at moderate depths (ca. 50 m), while king penguins (Aptenodytes patagonicus) feed on mesopelagic fish at deep depths (ca. 100–150 m). We instrumented 22 penguins with time-depth recorders during the breeding season of the 2014 southern summer, just before they went to sea. Birds were recaptured after one to five foraging trips and the dive data were analysed on the level of single dive cycles and entire dive bouts. Both species adjusted their diving behaviour and modulated their foraging activity in accordance with their experience in their previous dives. Foraging activity during a dive (in terms of number of wiggles per dive) was greater if birds targeted the same depth as the previous dive. The penguins spent less time at the surface between two prey capture attempt dives than when a prey capture attempt dive was preceded by a non-prey capture attempt dive. Dive bout analyses showed that foraging activity increased with bout duration, while transit time during dives decreased with bout duration. Our findings are in general agreement with predictions based on optimal foraging models. The results suggest that penguins anticipated the depth of their next dive based on their encounter of a prey patch in the previous dive and optimized their chances of feeding success by spending minimal time at the surface and in transit to the patch depth. Once penguins detected a prey patch, these behavioural adjustments allowed them to rapidly return to that patch, increasing their chances of feeding again before the prey disperses. |
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394 |
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1432-1793 |
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yes |
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7737 |
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Author |
Winton V.H.L., Ming A., Caillon N., Hauge L. Jones A.E., Savarino J., Yang X., Frey M.M. |
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Title |
Deposition, recycling, and archival of nitrate stable isotopes between the air–snow interface: comparison between Dronning Maud Land and Dome C, Antarctica |
Type |
Journal |
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Year |
2020 |
Publication |
Atmospheric Chemistry and Physics |
Abbreviated Journal |
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Volume |
20 |
Issue |
9 |
Pages |
5861–5885 |
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Keywords |
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Abstract |
The nitrogen stable isotopic composition in nitrate (δ15N-NO−3) measured in ice cores from low-snow-accumulation regions in East Antarctica has the potential to provide constraints on past ultraviolet (UV) radiation and thereby total column ozone (TCO) due to the sensitivity of nitrate (NO−3) photolysis to UV radiation. However, understanding the transfer of reactive nitrogen at the air–snow interface in polar regions is paramount for the interpretation of ice core records of δ15N-NO−3 and NO−3 mass concentrations. As NO−3 undergoes a number of post-depositional processes before it is archived in ice cores, site-specific observations of δ15N-NO−3 and air–snow transfer modelling are necessary to understand and quantify the complex photochemical processes at play. As part of the Isotopic Constraints on Past Ozone Layer Thickness in Polar Ice (ISOL-ICE) project, we report new measurements of NO−3 mass concentration and δ15N-NO−3 in the atmosphere, skin layer (operationally defined as the top 5 mm of the snowpack), and snow pit depth profiles at Kohnen Station, Dronning Maud Land (DML), Antarctica. We compare the results to previous studies and new data, presented here, from Dome C on the East Antarctic Plateau. Additionally, we apply the conceptual 1D model of TRansfer of Atmospheric Nitrate Stable Isotopes To the Snow (TRANSITS) to assess the impact of NO−3 recycling on δ15N-NO−3 and NO−3 mass concentrations archived in snow and firn. We find clear evidence of NO−3 photolysis at DML and confirmation of previous theoretical, field, and laboratory studies that UV photolysis is driving NO−3 recycling and redistribution at DML. Firstly, strong denitrification of the snowpack is observed through the δ15N-NO−3 signature, which evolves from the enriched snowpack (−3 ‰ to 100 ‰), to the skin layer (−20 ‰ to 3 ‰), to the depleted atmosphere (−50 ‰ to −20 ‰), corresponding to mass loss of NO−3 from the snowpack. Based on the TRANSITS model, we find that NO−3 is recycled two times, on average, before it is archived in the snowpack below 15 cm and within 0.75 years (i.e. below the photic zone). Mean annual archived δ15N-NO−3 and NO−3 mass concentration values are 50 ‰ and 60 ng g−1, respectively, at the DML site. We report an e-folding depth (light attenuation) of 2–5 cm for the DML site, which is considerably lower than Dome C. A reduced photolytic loss of NO−3 at DML results in less enrichment of δ15N-NO−3 than at Dome C mainly due to the shallower e-folding depth but also due to the higher snow accumulation rate based on TRANSITS-modelled sensitivities. Even at a relatively low snow accumulation rate of 6 cm yr−1 (water equivalent; w.e.), the snow accumulation rate at DML is great enough to preserve the seasonal cycle of NO−3 mass concentration and δ15N-NO−3, in contrast to Dome C where the depth profiles are smoothed due to longer exposure of surface snow layers to incoming UV radiation before burial. TRANSITS sensitivity analysis of δ15N-NO−3 at DML highlights that the dominant factors controlling the archived δ15N-NO−3 signature are the e-folding depth and snow accumulation rate, with a smaller role from changes in the snowfall timing and TCO. Mean TRANSITS model sensitivities of archived δ15N-NO−3 at the DML site are 100 ‰ for an e-folding depth change of 8 cm, 110 ‰ for an annual snow accumulation rate change of 8.5 cm yr−1 w.e., 10 ‰ for a change in the dominant snow deposition season between winter and summer, and 10 ‰ for a TCO change of 100 DU (Dobson units). Here we set the framework for the interpretation of a 1000-year ice core record of δ15N-NO−3 from DML. Ice core δ15N-NO−3 records at DML will be less sensitive to changes in UV than at Dome C; however the higher snow accumulation rate and more accurate dating at DML allows for higher-resolution δ15N-NO−3 records. |
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Programme |
1177 |
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Bachelor's thesis |
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ISSN |
1680-7316 |
ISBN |
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Approved |
yes |
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Call Number |
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Serial |
7855 |
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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 |
Type |
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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Programme |
1192 |
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ISSN |
2045-8827 |
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yes |
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Call Number |
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Serial |
7964 |
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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 |
Albane Barbero, Camille Blouzon, Joël Savarino, Nicolas Caillon, Aurélien Dommergue, Roberto Grilli |
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Title |
A compact incoherent broadband cavity-enhanced absorption spectrometer for trace detection of nitrogen oxides, iodine oxide and glyoxal at levels below parts per billion for field applications |
Type |
Journal |
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Year |
2020 |
Publication |
Atmospheric Measurement Techniques |
Abbreviated Journal |
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Volume |
13 |
Issue |
8 |
Pages |
4317-4331 |
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Abstract |
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Programme |
1028,1177 |
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Thesis |
Bachelor's thesis |
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ISSN |
1867-1381 |
ISBN |
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Approved |
yes |
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Call Number |
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Serial |
7854 |
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| Permanent link to this record |
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Author |
Philippe Ricaud, Paolo Grigioni, Romain Roehrig, Pierre Durand, Dana E. Veron |
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Title |
Trends in Atmospheric Humidity and Temperature above Dome C, Antarctica Evaluated from Observations and Reanalyses |
Type |
Journal |
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Year |
2020 |
Publication |
Atmosphere |
Abbreviated Journal |
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Volume |
11 |
Issue |
8 |
Pages |
836 |
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Keywords |
meteorological reanalyses microwave radiometer precipitable water radiosondes SAM index temperature trends |
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Abstract |
The time evolution of humidity and temperature above Dome C (Antarctica) has been investigated by considering data from (1) meteorological radiosondes (2005–2017), (2) the microwave radiometer HAMSTRAD (2012–2017), (3) four modern meteorological reanalyses (1980–2017) and (4) the southern annular mode (SAM) index (1980–2017). From these observations (2005–2017), a significant moistening trend (0.08 ± 0.06 kg m−2 dec−1) is associated with a significant warming trend (1.08 ± 0.55 K dec−1) in summer. Conversely, a significant drying trend of −0.04 ± 0.03 kg m−2 dec−1 (−0.05 ± 0.03 kg m−2 dec−1) is associated with a significant cooling trend of −2.4 ± 1.2 K dec−1 (−5.1 ± 2.0 K dec−1) in autumn (winter), with no significant trends in the spring. We demonstrate that 1) the trends identified in the radiosondes (2005–2017) are also present in the reanalyses and 2) the multidecadal variability of integrated water vapor and near-surface temperature (1980–2017) is strongly influenced by variability in the SAM index for all seasons but spring. Our study suggests that the decadal trends observed in humidity and near-surface temperature at Dome C (2005–2017) reflect the multidecadal variability of the atmosphere, and are not indicative of long-term trends that may be related to global climate change. |
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Programme |
910 |
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Bachelor's thesis |
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Series Title |
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Edition |
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ISSN |
2073-4433 |
ISBN |
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Approved |
yes |
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Call Number |
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Serial |
7838 |
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| Permanent link to this record |
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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 |
Type |
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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yes |
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Call Number |
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Serial |
7946 |
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Author |
Luis R. Pertierra, Nicolás I. Segovia, Daly Noll, Pablo A. Martinez, Patricio Pliscoff, Andrés Barbosa, Pedro Aragón, Andrea Raya Rey, Pierre Pistorius, Phil Trathan, Andrea Polanowski, Francesco Bonadonna, Céline Le Bohec, Ke Bi, Cynthia Y. Wang-Claypool, Daniel González-Acuña, Gisele P. M. Dantas, Rauri C. K. Bowie, Elie Poulin, Juliana A. Vianna |
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Title |
Cryptic speciation in gentoo penguins is driven by geographic isolation and regional marine conditions: Unforeseen vulnerabilities to global change |
Type |
Journal |
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Year |
2020 |
Publication |
Diversity and distributions |
Abbreviated Journal |
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Volume |
26 |
Issue |
8 |
Pages |
958-975 |
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Keywords |
diversification ecological niche overlap gentoo penguin subspecies |
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Abstract |
Aim The conservation of biodiversity is hampered by data deficiencies, with many new species and subspecies awaiting description or reclassification. Population genomics and ecological niche modelling offer complementary new tools for uncovering functional units of phylogenetic diversity. We hypothesize that phylogenetically delineated lineages of gentoo penguins (Pygoscelis papua) distributed across Antarctica and sub-Antarctic Islands are subject to spatially explicit ecological conditions that have limited gene flow, facilitating genetic differentiation, and thereby speciation processes. Location Antarctica and sub-Antarctic area. Methods We identify divergent lineages for gentoo penguins using ddRAD-seq and mtDNA, and generated species distribution models (SDMs) based on terrestrial and marine parameters. Results Analyses of our genomic data supports the existence of four major lineages of gentoo penguin: (i) spanning the sub-Antarctic archipelagos north of the Antarctic Polar Front (APF); (ii) Kerguelen Island; (iii) South America; and (iv) across maritime Antarctic and the Scotia Arc archipelagos. The APF, a major current system around Antarctica, acts as the most important barrier separating regional sister lineages. Our ecological analyses spanning both the terrestrial (breeding sites) and marine (feeding sites) realms recover limited niche overlap among the major lineages of gentoo penguin. We observe this pattern to correspond more closely with regional differentiation of marine conditions than to terrestrial macroenvironmental features. Main conclusions Recognition of regional genetic lineages as discrete evolutionary entities that occupy distinct ecological niches and also differ morphologically should be considered a priority for conservation. Gentoo penguins provide a good example of how conservation policy can be directly impacted by new insights obtained through the integration of larger genomic datasets with novel approaches to ecological modelling. This is particularly pertinent to polar environments that are among the most rapidly changing environments on earth. |
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Programme |
137,354 |
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Thesis |
Bachelor's thesis |
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Series Issue |
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ISSN |
1472-4642 |
ISBN |
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Medium |
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Approved |
yes |
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Call Number |
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Serial |
7950 |
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| Permanent link to this record |
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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 |
ISBN |
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Approved |
yes |
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Call Number |
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Serial |
8077 |
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| Permanent link to this record |
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Author |
Amandine Kaiser, Davide Faranda, Sebastian Krumscheid, Danijel Belušić, Nikki Vercauteren |
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Title |
Detecting Regime Transitions of the Nocturnal and Polar Near-Surface Temperature Inversion |
Type |
Journal |
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Year |
2020 |
Publication |
Journal of the atmospheric sciences |
Abbreviated Journal |
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Volume |
77 |
Issue |
8 |
Pages |
2921-2940 |
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Keywords |
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Abstract |
Abstract Many natural systems undergo critical transitions, i.e., sudden shifts from one dynamical regime to another. In the climate system, the atmospheric boundary layer can experience sudden transitions between fully turbulent states and quiescent, quasi-laminar states. Such rapid transitions are observed in polar regions or at night when the atmospheric boundary layer is stably stratified, and they have important consequences in the strength of mixing with the higher levels of the atmosphere. To analyze the stable boundary layer, many approaches rely on the identification of regimes that are commonly denoted as weakly and very stable regimes. Detecting transitions between the regimes is crucial for modeling purposes. In this work a combination of methods from dynamical systems and statistical modeling is applied to study these regime transitions and to develop an early warning signal that can be applied to nonstationary field data. The presented metric aims to detect nearing transitions by statistically quantifying the deviation from the dynamics expected when the system is close to a stable equilibrium. An idealized stochastic model of near-surface inversions is used to evaluate the potential of the metric as an indicator of regime transitions. In this stochastic system, small-scale perturbations can be amplified due to the nonlinearity, resulting in transitions between two possible equilibria of the temperature inversion. The simulations show such noise-induced regime transitions, successfully identified by the indicator. The indicator is further applied to time series data from nocturnal and polar meteorological measurements. |
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1013 |
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0022-4928, 1520-0469 |
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yes |
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8151 |
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