Thatje Sven

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  • Article
    ASPIRE : the Amundsen Sea Polynya International Research Expedition
    (The Oceanography Society, 2012-09) Yager, Patricia L. ; Sherrell, Robert M. ; Stammerjohn, Sharon E. ; Alderkamp, Anne-Carlijn ; Schofield, Oscar M. E. ; Abrahamsen, E. Povl ; Arrigo, Kevin R. ; Bertilsson, Stefan ; Garay, D. Lollie ; Guerrero, Raul ; Lowry, Kate E. ; Moksnes, Per-Olav ; Ndungu, Kuria ; Post, Anton F. ; Randall-Goodwin, Evan ; Riemann, Lasse ; Severmann, Silke ; Thatje, Sven ; van Dijken, Gert L. ; Wilson, Stephanie
    In search of an explanation for some of the greenest waters ever seen in coastal Antarctica and their possible link to some of the fastest melting glaciers and declining summer sea ice, the Amundsen Sea Polynya International Research Expedition (ASPIRE) challenged the capabilities of the US Antarctic Program and RVIB Nathaniel B. Palmer during Austral summer 2010–2011. We were well rewarded by both an extraordinary research platform and a truly remarkable oceanic setting. Here we provide further insights into the key questions that motivated our sampling approach during ASPIRE and present some preliminary findings, while highlighting the value of the Palmer for accomplishing complex, multifaceted oceanographic research in such a challenging environment.
  • Article
    The discovery of new deep-sea hydrothermal vent communities in the Southern Ocean and implications for biogeography
    (Public Library of Science, 2012-01-03) Rogers, Alex D. ; Tyler, Paul A. ; Connelly, Douglas P. ; Copley, Jonathan T. ; James, Rachael H. ; Larter, Robert D. ; Linse, Katrin ; Mills, Rachel A. ; Naveira Garabato, Alberto C. ; Pancost, Richard D. ; Pearce, David A. ; Polunin, Nicholas V. C. ; German, Christopher R. ; Shank, Timothy M. ; Boersch-Supan, Philipp H. ; Alker, Belinda J. ; Aquilina, Alfred ; Bennett, Sarah A. ; Clarke, Andrew ; Dinley, Robert J. J. ; Graham, Alastair G. C. ; Green, Darryl R. H. ; Hawkes, Jeffrey A. ; Hepburn, Laura ; Hilario, Ana ; Huvenne, Veerle A. I. ; Marsh, Leigh ; Ramirez-Llodra, Eva ; Reid, William D. K. ; Roterman, Christopher N. ; Sweeting, Christopher J. ; Thatje, Sven ; Zwirglmaier, Katrin
    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.
  • Article
    Climate change and the threat of novel marine predators in Antarctica
    (John Wiley & Sons, 2017-11-30) Smith, Kathryn E. ; Aronson, Richard B. ; Steffel, Brittan V. ; Amsler, Margaret O. ; Thatje, Sven ; Singh, Hanumant ; Anderson, Jeff ; Brothers, Cecilia ; Brown, Alastair ; Ellis, Daniel S. ; Havenhand, Jon N. ; James, William R. ; Moksnes, Per-Olav ; Randolph, Allison W. ; Sayre-McCord, Thomas ; McClintock, James B.
    Historically low temperatures have severely limited skeleton-breaking predation on the Antarctic shelf, facilitating the evolution of a benthic fauna poorly defended against durophagy. Now, rapid warming of the Southern Ocean is restructuring Antarctic marine ecosystems as conditions become favorable for range expansions. Populations of the lithodid crab Paralomis birsteini currently inhabit some areas of the continental slope off Antarctica. They could potentially expand along the slope and upward to the outer continental shelf, where temperatures are no longer prohibitively low. We identified two sites inhabited by different densities of lithodids in the slope environment along the western Antarctic Peninsula. Analysis of the gut contents of P. birsteini trapped on the slope revealed them to be opportunistic invertivores. The abundances of three commonly eaten, eurybathic taxa—ophiuroids, echinoids, and gastropods—were negatively associated with P. birsteini off Marguerite Bay, where lithodid densities averaged 4280 ind/km2 at depths of 1100–1499 m (range 3440–5010 ind/km2), but not off Anvers Island, where lithodid densities were lower, averaging 2060 ind/km2 at these depths (range 660–3270 ind/km2). Higher abundances of lithodids appear to exert a negative effect on invertebrate distribution on the slope. Lateral or vertical range expansions of P. birsteini at sufficient densities could substantially reduce populations of their benthic prey off Antarctica, potentially exacerbating the direct impacts of rising temperatures on the distribution and diversity of the contemporary shelf benthos.