LARISSA - LARsen Ice Shelf System, Antarctica, a NSF-funded project.

LARISSA - LARsen Ice Shelf System, Antarctica, a NSF-funded project.
We are conducting an integrated, multi-disciplinary field program to address the rapid and fundamental changes occurring in the Antarctic Peninsula region as a consequence of the abrupt collapse of the Larsen B Ice Shelf in the fall of 2002. A profound transformation in ecosystem structure and function is occurring in coastal waters of the western Weddell Sea. This transformation appears to be yielding a redistribution of energy flow between chemoautotrophic and photosynthetic production, and to be causing the rapid demise of the extraordinary seep ecosystem discovered beneath the ice shelf, providing an ideal opportunity to test fundamental paradigms in ecosystem evolution.

Tuesday, January 12, 2010

Arriving in Antarctica

10 January – *Antarctic Sound and Whale Bone Lander Recovery.* We awoke on the morning of 9 Jan to sunlight glinting off nearby icebergs and distant glaciers as we passed through the Antarctic Sound. In these protected waters, the ocean was smooth and we made excellent time through the extraordinary scenery of the Antarctic Peninsula. By 6 in the evening (1800 hrs) we were off Vega Island in the Weddell Sea, in position to recover a free-vehicle whale-bone experiment placed on the seafloor 10 months earlier. The “bone lander” consists of specialized animals that colonize whale bones. The lander is dropped to the seafloor with flotation, a lead ballast weight, and an acoustic release holding the weight; at the end of an experiment, the acoustic release drops the weight following an acoustic signal from the research vessel, rising to the ocean’s surface with whale bones for recovery. Such landers are generally reliable but certainly not failsafe – they fail to surface about 5-10% of the time, often for no obvious reason. Thus, recalling a lander always is filled with suspense, especially if your scientific research (i.e., job) depends on it. This bone lander gave us plenty of suspense, remaining on the seafloor for an hour after it was recalled. Finally it surfaced, apparently having been fouled on a glacial boulder until the bottom current shifted directions. To our delight, the recovered whale bones were covered with a special fauna --- hundreds of bone eating worms called Osedax (picture 10) that especially like whale bones, mats of sulfur bacteria, and thousands of segmented (poychaete) worms in the family Dorvilleidae, which contains a remarkable diversity species living on whale bones throughout the oceans. Our small seafloor ecology group (Laura Grange, David Honig and Craig Smith) spent 2.5 days (broken by 6 hours sleep) painstakingly picking the animals off the whale bones, preserving some for DNA analyses, some for food web studies using stable isotopes, and some for biodiversity studies using classical taxonomy (i.e., based or animal “shape” or morphology). Although exhausted by the end of our bone-processing ordeal, we were in excellent spirits. It is clear that we have new species of whale-bone animals, and that we will fill in an important gap in the biogeography and feeding ecology the global “whale-fall fauna,” helping the elucidate the effects of whales, and the impacts of whaling, on marine biodiversity around Antarctica. By the time we had finished our whale-bone tasks, we were stuck in the sea ice, but that is a story yet to come.

The mucus tubes of the whale-bone eating worms Osedax on a whale bone recovered after 10 months on the seafloor in the Weddell Sea, Antarctica.

1 comment:

  1. Congrats on the retrieval and best luck for the rest of the cruise!