Découvertes d'espèces nouvelles en Antarctique

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D'étranges espèces sous-marines découvertes dans l'Antarctique

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Pour ceux que cela interesse, le resume ainsi que la synthese propose par les auteurs:

The Discovery of New Deep-Sea Hydrothermal Vent Communities intheSouthern OceanandImplications for Biogeography

Alex D. Rogers1, Paul A. Tyler2, Douglas P. Connelly3, Jon T. Copley2, Rachael James3, Robert D. Larter4, Katrin Linse4, Rachel A. Mills2, Alfredo Naveira Garabato2, Richard D. Pancost5, David A. Pearce4, Nicholas V. C. Polunin6, Christopher R. German7, Timothy Shank7, Philipp H. Boersch-Supan1,8, Belinda J. Alker3, Alfred Aquilina2, Sarah A. Bennett3¤a, Andrew Clarke4, Robert J. J. Dinley2, Alastair G. C. Graham4, Darryl R. H. Green3, Jeffrey A. Hawkes2,3, Laura Hepburn2, Ana Hilario9, Veerle A. I. Huvenne3, Leigh Marsh2, Eva Ramirez-Llodra10, William D. K. Reid6, Christopher N. Roterman1,2, Christopher J. Sweeting6, Sven Thatje2, Katrin Zwirglmaier4

1 Department of Zoology, University of Oxford, Oxford, United Kingdom, 2 Ocean and Earth Science, National Oceanography Centre, Southampton, University of Southampton, Southampton, United Kingdom, 3 Natural Environment Research Council, National Oceanography Centre, Southampton, Southampton, United Kingdom, 4 British Antarctic Survey, Cambridge, United Kingdom, 5 School of Chemistry, University of Bristol, Bristol, United Kingdom, 6 School of Marine Science and Technology, Newcastle University, Newcastle upon Tyne, United Kingdom, 7 Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America, 8 Scottish Oceans Institute, University of St Andrews, St Andrews, United Kingdom, 9 Centro de Estudos do Ambiente e do Mar, Departmento Biologia, Universidade de Aveiro, Aveiro, Portugal, 10 Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas, Barcelona, Spain

Abstract

Since the first discovery of deep-sea hydrothermal vents along the Galápagos Rift in 1977, numerous vent sites and endemic faunal assemblages have been found along mid-ocean ridges and back-arc basins at low to mid latitudes. These discoveries have suggested the existence of separate biogeographic provinces in the Atlantic and the North West Pacific, the existence of a province including the South West Pacific and Indian Ocean, and a separation of the North East Pacific, North East Pacific Rise, and South East Pacific Rise. The Southern Ocean is known to be a region of high deep-sea species diversity and centre of origin for the global deep-sea fauna. It has also been proposed as a gateway connecting hydrothermal vents in different oceans but is little explored because of extreme conditions. Since 2009 we have explored two segments of the East Scotia Ridge (ESR) in the Southern Ocean using a remotely operated vehicle. In each segment we located deep-sea hydrothermal vents hosting high-temperature black smokers up to 382.8°C and diffuse venting. The chemosynthetic ecosystems hosted by these vents are dominated by a new yeti crab (Kiwa n. sp.), stalked barnacles, limpets, peltospiroid gastropods, anemones, and a predatory sea star. Taxa abundant in vent ecosystems in other oceans, including polychaete worms (Siboglinidae), bathymodiolid mussels, and alvinocaridid shrimps, are absent from the ESR vents. These groups, except the Siboglinidae, possess planktotrophic larvae, rare in Antarctic marine invertebrates, suggesting that the environmental conditions of the Southern Ocean may act as a dispersal filter for vent taxa. Evidence from the distinctive fauna, the unique community structure, and multivariate analyses suggest that the Antarctic vent ecosystems represent a new vent biogeographic province. However, multivariate analyses of species present at the ESR and at other deep-sea hydrothermal vents globally indicate that vent biogeography is more complex than previously recognised.


Author Summary

Deep-sea hydrothermal vents are mainly associated with seafloor spreading at mid-ocean ridges and in basins near volcanic island arcs. They host animals found nowhere else that derive their energy not from the sun but from bacterial oxidation of chemicals in the vent fluids, particularly hydrogen sulphide. Hydrothermal vents and their communities of organisms have become important models for understanding the origins and limits of life as well as evolution of island-like communities in the deep ocean. We describe the fauna associated with high-temperature hydrothermal vents on the East Scotia Ridge, Southern Ocean, to our knowledge the first to be discovered in Antarctic waters. These communities are dominated by a new species of yeti crab, stalked barnacles, limpets and snails, sea anemones, and a predatory seven-armed starfish. Animals commonly found in hydrothermal vents of the Pacific, Atlantic, and Indian Oceans, including giant Riftia tubeworms, annelid worms, vent mussels, vent crabs, and vent shrimps, were not present at the Southern Ocean vents. These discoveries suggest that the environmental conditions of the Southern Ocean may act as a barrier to some vent animals and that the East Scotia Ridge communities form a new biogeographic province with a unique species composition and structure.

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Le crabe-yéti, c'est évidemment un Mi-Go.

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