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Landais A., Barnola J.M., Awamura K., Caillon N., Delmotte M., Van Ommen T., Dreyfus G., Jouzel J., Masson-Delmotte V., Minster B., Freitag J., Leuenberger M., Schwander J., Huber C., Etheridge D. & Morgan V. (2006). Firn-air d15N in modern polar sites and glacial-interglacial ice: a model-data mismatch during glacial periods in Antarctica? Quat Sci Rev, 25(1-2), 49–62.
Abstract: The phase lag between atmospheric composition (air bubbles) and temperature (water isotopes) can be quantified from ice cores provided that the age difference between entrapped air and the surrounding air can be correctly estimated. This difference depends on the lock-in depth (LID), when air no longer mixes with the atmosphere. The LID can be estimated from firnification models or from the air isotopic composition (?15N and ?40Ar). Both methods give consistent results for Greenland and one coastal site in Antarctica (Byrd). New firn measurements in Greenland (NorthGRIP) and Antarctica (Berkner Island, BAS depot, Dome C) confirm that firnification models correctly reproduce the present LID over a large range of surface conditions. However, a systematic mismatch is observed for the Last Glacial Maximum (LGM) in East Antarctic sites (Vostok, Dome C, Dome F) questioning the model's validity. Here we use new ?15N measurements from two coastal Antarctic sites (Kohnen Station and Law Dome) providing depth estimates again distinct from firnification model calculations. We show that this discrepancy can be resolved by revising the estimate of past accumulation rates. ?15N measurements can therefore help to constrain past accumulation rate and improve ice core dating.
Programme: 960
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Hosie Graham, Koubbi Philippe, Riddle Martin, Ozouf-Costaz Catherine, Moteki Masato, Fukuchi Mitsuo, Ameziane Nadia, Ishimaru Takashi, Goffart Anne, . (2011). CEAMARC, the Collaborative East Antarctic Marine Census for the Census of Antarctic Marine Life (IPY # 53): An overview
. Polar Science, 5(2), 75–87.
Keywords: CEAMARC, CAML, Marine biodiversity, Pelagic, Benthos,
Programme: 1124;1142
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Lacarra M, Houssais M-N, Sultan E, Rintoul SR, Herbaut C, . (2011). Polar Science, 5(2), 88–103.
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Giraldo Carolina, Cherel Yves, Vallet Carole, Mayzaud Patrick, Tavernier Eric, Moteki Masato, Hosie Graham, Koubbi Philippe, . (2011). Ontogenic changes in the feeding ecology of the early life stages of the Antarctic silverfish (Pleuragramma antarcticum) documented by stable isotopes and diet analysis in the Dumont dUrville Sea (East Antarctica)
. Polar Science, 5(2), 252–263.
Abstract: The feeding ecology of the notothenioid fish Pleuragramma antarcticum was studied in the Dumont dUrville Sea (East Antarctica) near the French Antarctic station. Stable isotopes (13C and 15N) and diet contents were used in order to study dietary shifts between fish larvae and juveniles. All specimens had low 13C values (<24), a main characteristic of high-Antarctic pelagic species. Fish larvae showed differences in both carbon and nitrogen ratios when compared with juveniles. Muscle 15N values showed a difference of one trophic level (3) between larvae (6.7) and juveniles (9.710.0) and a trophic position of tertiary consumers. Diet content analyses (stereomicroscope and scanning electron microscopes) indicated that larvae are omnivorous, feeding on phytoplankton (mainly diatoms) as well as on zooplankton species. A positive relationship between 15N values and size was found and indicated a carnivorous diet for older specimens.
Keywords: 13C, 15N, Southern Ocean, Trophic relationships, Omnivory,
Programme: 109;1142
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Moteki Masato, Koubbi Philippe, Pruvost Patrice, Tavernier Eric, Hulley Percy-Alexander, . (2011). Polar Science, 5(2), 211–224.
Keywords: Pelagic fish, Community structure, East Antarctica, Mesopelagic fish, Notothenioids,
Programme: 1142
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Koubbi Philippe, O'Brien Colleen, Loots Christophe, Giraldo Carolina, Smith Martina, Tavernier Eric, Vacchi Marino, Vallet Carole, Chevallier Jean, Moteki Masato, . (2011). Spatial distribution and inter-annual variations in the size frequency distribution and abundances of Pleuragramma antarcticum larvae in the Dumont dUrville Sea from 2004 to 2010
. Polar Science, 5(2), 225–238.
Abstract: This paper investigates the abundance and distribution of Pleuragramma antarcticum larvae by size class in the Dumont dUrville Sea from 2004 to 2010. Samples were collected between Dumont dUrville station and the Mertz Glacier Tongue onboard the RV lAstrolabe for studying the inter-annual and spatial distribution of fish larvae and the TRV Umitaka Maru for looking at life stages vertical distributions. The seabed depression adjacent to the Mertz Glacier Tongue and in Commonwealth Bay hosted high abundances of small P. antarcticum larvae, while larger larvae were found in lower abundance and further offshore. We found that canyons, sea ice, stability of the water column and temperatures are important features for determining suitable areas for young larvae.
Keywords: Pleuragramma antarcticum, East Antarctic shelf, Fish larvae, Life cycle, Inter-annual variations,
Programme: 1142
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. (2011). Polar Science, 5(2), 286–297.
Keywords: Benthic, Ecological niche, Habitat, Pelagic, Southern Ocean, Stable isotopes,
Programme: 109;1124;1142
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Koubbi Philippe, Ozouf-Costaz Catherine, Goarant Anne, Moteki Masato, Hulley Percy-Alexander, Causse Romain, Dettai Agns, Duhamel Guy, Pruvost Patrice, Tavernier Eric, Post Alexandra L, Beaman Robin J, Rintoul Stephen R, Hirawake Toru, Hirano Daisuke, Ishimaru Takashi, Riddle Martin, Hosie Graham, . (2010). Estimating the biodiversity of the East Antarctic shelf and oceanic zone for ecoregionalisation: Example of the ichthyofauna of the CEAMARC (Collaborative East Antarctic Marine Census) CAML surveys
. Polar Science, 4(2), 115–133.
Abstract: Ecoregions are defined in terms of community structure as a function of abiotic or even anthropogenic forcing. They are meso-scale structures defined as the potential habitat of a species or the predicted communities geographic extent. We assume that they can be more easily defined for long-lived species, such as benthos or neritic fish, in the marine environment. Uncertainties exist for the pelagic realm because of its higher variability, plus little is known about the meso- and bathypelagic zones. A changing environment and modification of habitats will probably drive new communities from plankton to fish or top predators. We need baseline studies, such as those of the Census of Antarctic Marine Life, and databases like SCAR-MarBIN as tools for integrating all of these observations. Our objective is to understand the biodiversity patterns in the Southern Ocean and how these might change through time.
Keywords: East Antarctic shelf, Ichthyofauna, Ecoregionalisation, Generalized dissimilarity modeling, Dumont d'Urville Sea,
Programme: 1124;1142
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. (2021). The high diversity of Southern Ocean sea stars (Asteroidea) reveals original evolutionary pathways (Vol. 190). Bachelor's thesis, , .
Abstract: Benthic life in the Southern Ocean (SO) features unique life history traits and species assemblages, but the origin and evolution of many of these taxonomic groups is still unclear. Sea stars (Asteroidea) are a diversified and abundant component of benthic ecosystems in the SO, in which they can play key ecological roles. Former studies suggest that the diversity of the entire class is still poorly known and underestimated, hampering the assessment of the origin and evolution of the class in the SO. In the present study, we analyse spatial patterns of SO sea star diversity using an occurrence database of ~14,000 entries. The biogeographic analysis is coupled with the exploration of an extensive molecular phylogeny based on over 4,400 specimen sequences to inform, support and/or question the observed diversity patterns. We show that the current taxonomy of SO asteroids needs revision and that their diversity has generally been overlooked and misinterpreted. Molecular results highlight the recent diversification of most studied taxa, at genus and species levels, which supports an evolutionary scenario referring to successive invasion and exchange events between the SO and adjacent regions, and clade diversification during periods of rapid environmental changes driven by the succession of glacial cycles. Our work advocates for employing, and endorsing the use of extensive genetic barcode libraries for biodiversity studies.
Keywords: Antarctica Biodiversity COI mtDNA Echinodermata Evolution Phylogeography
Programme: 1044,1124
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. (2019). Cryptic speciation in Southern Ocean Aequiyoldia eightsii (Jay, 1839): Mio-Pliocene trans-Drake Passage separation and diversification (Vol. 174). Bachelor's thesis, , .
Abstract: The species of the genus Aequiyoldia Soot-Ryen, 1951, previously known as Yoldia, are common, soft-substratum, sareptid bivalves. In the Southern Ocean, Aequiyoldia eightsii (Jay, 1839) was originally described from the Antarctic Peninsula and has also been reported in southern South America. The species A. woodwardi (Hanley, 1960) was reported for the Falkland/Malvinas Islands and Tierra del Fuego, but this taxon has been recently synonymised within the broadly distributed A. eightsii. Aequiyoldia has received little attention across its distribution in the Southern Ocean, and although its taxonomy and systematics remain uncertain, all the species have been grouped under a single and broadly distributed unit: A. eightsii. Nevertheless, preliminary mtDNA comparisons demonstrated a marked genetic divergence (>7%) between A. eightsii populations from South America and Antarctic Peninsula. In order to further understand the diversity and biogeography of Aequiyoldia, we analyzed A. eightsii populations from different provinces of the Southern Ocean including South America (SA), the Falkland/Malvinas Islands (FI), the Antarctic Peninsula (AP), and Kerguelen Islands (KI). Individuals were characterized according to typical diagnostic morphological measurements and phylogenetic relationships were reconstructed based on mtDNA (cytochrome c oxidase subunit I). Patterns of genetic divergence of nucDNA intergenic transcribed spacers (ITS1, ITS2) were also estimated. The statistical analysis of external diagnostic characteristics revealed two morphotypes: (1) individuals with the morphology recorded for the nominal FI species, A. woodwardi, and (2) individuals from SA, AP, and KI, with the morphology recorded for A. eightsii. However, phylogenetic reconstructions based on mtDNA and nucDNA suggest the presence of at least five lineages within A. eightsii including: one lineage in Kerguelen Island, two lineages in the Antarctic Peninsula, one lineage in South America, and the last one restricted to the Falkland/Malvinas Islands. Such results are evidence that the Antarctic Polar Front represents an historical biogeographic barrier for this group and that after the separation of these lineages, they followed independent evolutionary pathways in different provinces of the Southern Ocean. Estimates of divergence time suggest that KI separated from other Aequiyoldia lineages close to the middle Miocene. Following this, the separation between the AP and SA lineages occurred at the end of the Miocene around 7.5?Ma. Finally, Aequiyoldia diversified during the Pliocene in Antarctic Peninsula (?4.5?Ma) and South America (?3.0?Ma). Individuals from FI exhibited morphological differences, and 4% of divergence from South American individuals, suggesting that A. woordwardi could be revalidated. Similarly, the marked molecular divergence between the KI and the rest of the recorded lineages also support the validity of A. kerguelensis (Thiele, 1931).
Keywords: Antarctic Peninsula Antarctic-Magellan Connection Biogeography Kerguelen Islands Morphometry Phylogeny South America Southern Ocean Systematics
Programme: 1044
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