Sea Technology

JUN 2017

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54 st / June 2017 www.sea-technology.com Future Larsen C Iceberg Likely to Survive to 10 Years On the Larsen C Ice Shelf in the Antarctic, a massive iceberg has begun to break off from the rest. The future iceberg will have a total surface area of nearly 6,000 sq. km. The Alfred Wegener Institute, Helm- holtz Centre for Polar and Marine Re- search has succeeded in modeling how Antarctic icebergs drift through the Southern Ocean and in identifying the physical factors behind their move- ment and their melting. How far the future Larsen C ice- berg will drift depends on whether it remains intact after calving or quickly breaks up into smaller pieces. Further, the iceberg may run aground for a time. Given its massive weight, the Larsen C iceberg will likely survive for eight to 10 years; according to the computer model, that's the maximum life expec- tancy for even the largest iceberg drifts. The potential routes produced by the model were compared with actual data on large icebergs from the Antarc- tic Iceberg Tracking Database and with GPS data from icebergs in the Weddell Sea. New Insight into Behavior of Volcanoes, Earthquakes Beneath the ocean, massive tecton- ic plates undergo subduction, which forms volcanic arcs that can be home to explosive volcanic eruptions and mega earthquakes. Researchers led by the Woods Hole Oceanographic Institution (WHOI) have discovered a previously unknown process involving the melting of in- tensely mixed metamorphic rocks— mélange rocks—that form through high stress during subduction at the slab-mantle boundary. The study shows that the prevailing fluid/sediment melt model cannot be correct. The research shows—for the first time—that mélange melting is the main driver of how the slab and mantle interact. Subduction zones are the main ar- eas where water and carbon dioxide contained within old seafloor are re- cycled back into the deep Earth, play- ing critical roles in the control of long- term climate and the evolution of the planet's heat budget. These complex processes can gen- erate catastrophic earthquakes and deadly tsunamis. The study's findings call for a re- evaluation of previously published data and a revision of concepts relating to subduction zone processes. Parrotfish React More to Competition than to Predators According to new research by UC Santa Barbara marine scientists, Chlo- rurus spilurus, known as the bullethead or daisy parrotfish, barely reacts to the presence of predators. Working in the waters off Mo'orea and the Palmyra Atoll, researchers ob- served almost constant competitive in- teractions between predators and bul- lethead parrotfish—the Pacific Ocean's most abundant parrotfish species —and other herbivorous fishes. They were constantly chasing each other, and this affected their feeding rates. Predators such as sharks, snappers and groupers frequently swam past the oceanresearch

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