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  • Springer  (2)
  • American Association for the Advancement of Science (AAAS)  (1)
  • 1
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During the joint Chilean-German-Italian Magellan “Victor Hensen” Campaign in November 1994, samples were taken on a cruise of the RV Victor Hensen in order to obtain faunistic information from the Beagle Channel. Peracarida are an important fraction of the macrobenthos and were sampled in high numbers. Using an epibenthic sledge, 104,618 individuals were collected in total, comprising 62,860 Amphipoda, 14,685 Cumacea, 17,992 Isopoda, 7,168 Mysidacea and 1,893 Tanaidacea. To allow comparisons between stations, these numbers were standardized to a 1,000 m trawling distance, yielding about 368,000 individuals from all stations. Peracarida were most abundant at station 1213, southeast of Isla Picton, in the oceanic area close to the eastern entrance of the Beagle Channel (166,361 ind./1,000 m). Generally, stations off the eastern entrance were characterized by a high number of Peracarida. In the Beagle Channel itself, however, the abundance decreased from east to west with a single peak in peracarid number in the channel east of Punta Yámana. Numbers were much lower at the western entrance (792 ind./1,000 m) and even fewer Peracarida were collected in the Magdalena Channel off Punta Sánchez. Lowest numbers were recorded close to the glacier Romanche and west of Isla Picton at two locations. The composition of peracarid crustaceans was analysed in relation to the background of hydrographical and sedimentological differences, nutrient availability, and knowledge of the other associated fauna in the Beagle Channel. The available data lead us to conclude that abundance and composition of peracarid taxa in and south of the Beagle Channel (off the eastern entrance) seem to be influenced mainly by sediment composition and hydrographical characteristics as indicated above.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2018-01-19
    Description: Hydrothermal vents on mid-oceanic ridges are patchily distributed and host many taxa endemic to deep-sea chemosynthetic environments, whose dispersal may be constrained by geographical barriers. The aim of this study was to investigate the connectivity of three populations of the ‘scaly-foot gastropod’ (Chrysomallon squamiferum Chen et al., 2015), a species endemic to hydrothermal vents in the Indian Ocean, amongst two vent fields on the Central Indian Ridge (CIR) and Longqi field, the first sampled vent field on the Southwest Indian Ridge (SWIR). Connectivity and population structure across the two mid-oceanic ridges were investigated using a 489-bp fragment of the cytochrome oxidase c subunit I (COI) gene. Phylogeographical approaches used include measures of genetic differentiation (FST), reconstruction of parsimony haplotype network, mismatch analyses and neutrality tests. Relative migrants per generation were estimated between the fields. Significant differentiation (FST = 0.28–0.29, P 〈 0.001) was revealed between the vent field in SWIR and the two in CIR. Signatures were detected indicating recent bottleneck events followed by demographic expansion in all populations. Estimates of relative number of migrants were relatively low between the SWIR and CIR, compared with values between the CIR vent fields. The present study is the first to investigate connectivity between hydrothermal vents across two mid-ocean ridges in the Indian Ocean. The phylogeography revealed for C. squamiferum indicates low connectivity between SWIR and CIR vent populations, with implications for the future management of environmental impacts for seafloor mining at hydrothermal vents in the region, as proposed for Longqi.
    Type: Article , PeerReviewed
    Format: text
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  • 3
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    American Association for the Advancement of Science (AAAS)
    In:  EPIC3Science, American Association for the Advancement of Science (AAAS), 382(6677), pp. 1384-1389, ISSN: 0036-8075
    Publication Date: 2024-02-22
    Description: The marine-based West Antarctic Ice Sheet (WAIS) is considered vulnerable to irreversible collapse under future climate trajectories, and its tipping point may lie within the mitigated warming scenarios of 1.5° to 2°C of the United Nations Paris Agreement. Knowledge of ice loss during similarly warm past climates could resolve this uncertainty, including the Last Interglacial when global sea levels were 5 to 10 meters higher than today and global average temperatures were 0.5° to 1.5°C warmer than preindustrial levels. Using a panel of genome-wide, single-nucleotide polymorphisms of a circum-Antarctic octopus, we show persistent, historic signals of gene flow only possible with complete WAIS collapse. Our results provide the first empirical evidence that the tipping point of WAIS loss could be reached even under stringent climate mitigation scenarios.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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