Barbero A. Grilli R., Blouzon C., Caillon N., Savarino, J. (2020). New Observations to Better Constrain NOx (NO + NO2) Concentrations on the Antarctic Plateau and to Resolve the Ambiguity in the NO2:NO Ratio.
Abstract: High southern latitude regions present specificities that are highly relevant for studying the climate in connection with the atmospheric chemistry. Contrary to regions of the rest of the world, Antarctica is still considered as a pristine environment not yet influenced by predominant anthropogenic emissions (with the notable exceptions of GHG) and thus represents the last continental-size natural laboratory. Polar snow-air-radiation interactions and the specific oxidant character of the polar atmosphere are key in order to decipher the right information buried in the ice and the current chemical stability of the polar atmosphere. Previous Antarctic campaigns have shown atmospheric similarities between the Antarctic Plateau (at Dome C, Concordia) and other regions. However, several differences are yet to be explained: the large NO2:NO ratios previously found in ambient air indicates the existence of an unknown source of NO2 above the Antarctic Plateau. These observations question either the reliability of previous measurements or the lack of our understanding of the NOx chemistry. Novel optical instruments based on the incoherent broadband cavity enhanced absorption spectroscopy technique (IBBCEAS) were developed. The instruments can measure simultaneously NO2, NOx and NO with detection limits of 11, 10 and 21 ppt, respectively (1σ) within 22 minutes of measurements. The two compact and transportable instruments were deployed during the 2019/20 Dome C summer campaign. Atmospheric measurements together with flux chamber experiments were performed for determining the snowpack NOx emissions and the NO2:NO ratio. The observations seem to differ from the conclusions of the previous Antarctic campaigns. Assuming steady state and maximum radiations, the theoretical NO2:NO ratio from the period observed in December was calculated to be 0.38 ± 0.15 and 0.31 ± 0.12 in January. The instruments measured a ratio close to steady state in December (0.25 ± 0.25) while the ratio observed in January (1.248 ± 0.792) indicates the presence of a strong NO oxidant or an unknown source of NO2. Flux chamber experiments on different types of snow were done during this campaign, and the results will help deepen our knowledge of Antarctic atmospheric chemistry.
Programme: 1177
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Barbero A., Grilli R., Blouzon C., Ahmed S., Thomas J.L., Frey M., Huang Y., Caillon N., Savarino J. (2021). Innovative approach for new estimation of NOx snow-source on the Antarctic Plateau.
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Barbora Chattová, Marc Lebouvier, Bart Van De Vijver. (2018). Morphological and taxonomical analysis of the terrestrial diatom genus Humidophila (Bacillariophyta) on Ile Amsterdam and Ile Saint-Paul (Southern Indian Ocean) (Vol. 336).
Abstract: During a survey of the non-marine diatom flora of the volcanic islands, Ile Amsterdam and Ile Saint-Paul (southern Indian Ocean), seven species belonging to the terrestrial diatom genus Humidophila have been recorded. Apart from five previously known taxa (Humidophila contenta, H. crozetikerguelensis, H. gallica, H. brekkaensis, H. vidalii), two taxa could not be identified based on the currently available literature and are described as new to science: Humidophila amsterdamensis sp. nov. and Humidophila rouhaniana sp. nov. Detailed morphological descriptions of these taxa are given based on both light (LM) and scanning electron microscopy (SEM) observations. The morphological features of each taxon have been compared with similar species and notes on their ecology and associated diatom communities have been added.
Keywords: ALgae Bacillariophyta diatoms ecology Humidophila morphology new species
Programme: 136
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Barbora Chattová, Marc Lebouvier, Myriam De Haan, Bart Van de Vijver. (2017). The genus Luticola (Bacillariophyta) on Ile Amsterdam and Ile Saint-Paul (Southern Indian Ocean) with the description of two new species.
Abstract: Five species of the terrestrial diatom genus Luticola D.G.Mann were found during a taxonomic survey of two small volcanic islands, Ile Amsterdam and Ile Saint-Paul (Southern Indian Ocean). Apart from the two already known Luticola species L. beyensii Van de Vijver et al. and L. subcrozetensis Van de Vijver et al., two new species are described: L. ivetana Chattová & Van de Vijver sp. nov. and L. vancampiana Chattová & Van de Vijver sp. nov. Finally, one, up to now unknown, Luticola species is briefly discussed and illustrated. Detailed morphological descriptions of these taxa are provided based on both light and scanning electron microscopy observations. Morphological features of the new species are compared to morphologically similar taxa, and notes on their ecology and biogeography are added.
Keywords: Bacillariophyta diatoms Luticola morphology new species
Programme: 136
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Barbora Chattová, Marc Lebouvier, Vít Syrovátka, Bart Van de Vijver. (2021). Moss-inhabiting diatom communities from Ile Amsterdam (TAAF, southern Indian Ocean) (Vol. 154).
Abstract: Background and aims – Despite the ongoing taxonomical revision of the entire (sub)-Antarctic diatom flora, our knowledge on the ecology and community associations of moss-inhabiting diatoms is still rather limited. In the present study, our research aim was to survey the diversity together with the environmental factors structuring the epiphytic moss diatom communities on Ile Amsterdam (TAAF), a small volcanic island in the southern Indian Ocean.Material and methods – A morphology-based dataset and (physico)chemical measurements were used for the ecological and biogeographical analysis of moss-inhabiting diatom flora from Ile Amsterdam. In total, 148 moss samples were examined using light microscopy.Key results – The analysis revealed the presence of 125 diatom taxa belonging to 38 genera. The uniqueness of the Ile Amsterdam diatom flora is mainly reflected by the species composition of the dominant genera Pinnularia, Nitzschia, Humidophila, and Luticola, with a large number of unknown and often new species. This highly specific diatom flora, together with differences in the habitats sampled and the isolated position of the island, resulted in very low similarity values between Ile Amsterdam and the other islands of the Southern Ocean. From a biogeographical point of view, 40% of the taxa have a typical cosmopolitan distribution, whereas 22% of all observed species can be considered endemic to Ile Amsterdam, with another 17% species showing a restricted sub-Antarctic distribution. The NMDS analysis, based on a cluster dendrogram, divides the samples into six main groups. For each group, indicator species were determined. Both environmental data and diatom distributions indicate that apart from elevation, specific conductance, pH, and moisture are the major factors determining the structure of moss-inhabiting diatom communities on Ile Amsterdam.Conclusion – The isolated geographic position and unique climatological and geological features of the island shaped the presence of a unique diatom flora, characterised by many endemic species. The results of the study are of prime importance for further (palaeo-)ecological and biogeographical research.
Keywords: Bacillariophyta diatoms ecology Ile Amsterdam mosses southern Indian Ocean sub-Antarctic region
Programme: 136
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Barbraud C, Rolland V, Jenouvrier S, Nevoux M, Delord K, Weimerskirch H, . (2012). Effects of climate change and fisheries bycatch on Southern Ocean seabirds: a review
. Mar Ecol Prog Ser, 454, 285–307.
Abstract: Over the last century, major climate changes and intense human exploitation of natural living resources have occurred in the Southern Ocean, potentially affecting its ecosystems up to top marine predators. Fisheries may also directly affect seabirds through bycatch and additional food resources provided by discards. The past 20 yr of research has seen an increasing number of studies investigating the effects of climate change and fisheries activities on Southern Ocean seabirds. Here, we review these studies in order to identify patterns in changes in distribution, phenology, demography and population dynamics in response to changes in climate and fisheries bycatch. Shifts in distribution and breeding phenology were documented in parallel to increases in sea-surface temperatures and changes in sea-ice cover. Above all warm sea-surface temperatures negatively affected demographic parameters, although exceptions were found. Relationships suggest non-linear effects of sea-ice cover on demographic parameters and population dynamics, with optimum sea-ice cover conditions appearing to be the rule. Fishing efforts were mainly negatively related to survival rates, and only for a few species positively related to breeding success. A handful of studies found that chronic mortality of immature birds due to fisheries negatively affected populations. Climate factors and fisheries bycatch may simultaneously affect demographic parameters in a complex way, which can be integrated in population models to project population trajectories under future climate or fisheries scenarios. Needed are studies that integrate other environmental factors, trophic levels, foraging behaviour, climate−fisheries interactions, and the mechanisms underlying phenotypic plasticity, such as some pioneering studies conducted elsewhere.
Programme: 109
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Barbraud C. (1995). Covariations de la taille corporelle et des paramétres d'histoire de vie chez le Petrel des neiges..
Abstract: D.E.A.'Biologie des Populations et Eco-Ethologie
Programme: 109
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Barbraud C. (1999). Aspects écologiques et évolutifs de la variation de la taille corporelle chez le Petrel des Neiges, Pagodroma Nivea..
Abstract: Thèse pour obtenir le Grade de Docteur de l'Université de Tours, Université François Rabelais Tours
Programme: 109
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Barbraud C. (1999). Subspecies-selective predation of snow petrels by skuas. Oikos, 86, 275–282.
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Barbraud C. (2000). Natural selection on body size traits in a long-lived bird, the snow petrel Pagodroma nivea. J. Evol. Biol., 1, 81–88.
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