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.

Sunday, January 31, 2010

Sailing back to the Weddell Sea

21-29 January. After nearly one month at sea, we are finally heading for our
primary study sites on the east side of the Antarctic Peninsula in the 
Weddell Sea (near Cape Disappointment; see the map a few posts ago). Until now we have been
 locked out of the Weddell Sea by an unseasonably high concentration of sea
 ice, forced to conduct helicopter operations from the west side, trying to
 fly over the mountainous peninsula. On all but three days,
the clouds have been so low that helo operations were cancelled leaving us 
to study fjords on the west side of the Peninsula. While fascinating,
 these fjords are not the focus of our LARISSA Project, designed to assess 
the ecosystem impacts of the climate-change induced melting of the Larsen B
Ice Shelf. Thus, while we have been surrounded by beautiful scenery, 
enhanced by the passage of a 65-foot French yacht (picture below), our spirits 
have been low: we have been planning for years to conduct this exciting 
climate-change research in the Weddell Sea and we are unlikely to get a 
second chance!

One of our helicopters flying from the ship over the mountains 
of the Antarctic Peninsula at Barilari Bay. These rides can be a thrill a
 minute in the downdrafts of the catabatic winds coming down off the 

65-foot French yacht we met cruising in Antartica. She is 
dwarfed by the icebergs. On a day like this, the Antarctica Peninsula
scenery is otherworldly. However, when the winds pick up, every bergie bit 
(small chunks of glacial ice) is a potential reef!

At long last, two developments have brightened our prospects. The first
 was the recognition that much of the glaciology work atop the Peninsula 
could be conducted by Twin Otter (or ski plane) flights from the British
 Base at Rothera, on west side of the Peninsula. This allowed us to drop 
our 5 glaciology colleagues off at Rothera, freeing the ship to head back
 for the Weddell without compromising the terrestrial components of LARISSA
 (even if the ship gets stuck in the ice!). Our trip south to Rothera
 passed by whimsically named islets (including Beer Island and Hennessey 
Island, to torment our teetotalling ship!) and through narrow passages, 
included the Tickle Channel (picture below), which fortunately failed to 
tickle our ship’s bottom. At Rothera Base we received a warm welcome 
from our British colleagues as well as the wildlife. At the
 end of our 12-hour visit, we had an international soccer match (in which
 the Brits exhibited their World-Cup prowess) followed by a party in 
Rothera’s lounge which ended as midnight tolled and our ship departed
 Rothera Harbor (with moons up)!

Early morning passage through the Tickle Channel on the way
south to Rothera Base. Seals and penguins dot the bergie bits in the
channel. The icebergs tickle the sides of the ship.

The residents of Rothera Base are so friendly that even the
crabeater seals will offer a kiss! "Don't show my wife!!"

The second positive development for LARISSA came from satellite images of
 the Weddell Sea -- the ice is starting to break out! This has been
 precipitated by long-awaited southwesterly winds combined with warming
 summer temperatures in the Weddell Sea. We are now racing around the tip 
of the Antarctic Peninsula once again, hoping to find, at most, broken ice
flows and leads (i.e., channels) through which the ship can maneuver. If 
all goes well, we still may have time to complete our oceanographic 
program, exploring animal colonization and cold-seep biotas at the seafloor 
under the recently broken out Larsen B Ice Shelf.

Because of our scientific difficulties, the cruise thus far has been
 bittersweet. Normally, after a month at sea, one falls into a rhythm
 characteristic of the ship’s routine, the scientific sampling program,
 and the unique suite of shipboard companions. This cruise has remained
 rythmless through forced changes in plans and shipboard companions on
 nearly a daily basis. One clear message is that research expeditions to
 Antarctica must be, if anything, flexible and opportunistic. Modern
oceanographic technology is still no match for a frozen Southern Ocean. 
However, as the sea ice wanes we now all hope to address our core
 oceanography program, and to begin sampling intensively around the clock. 
Despite the ice delays, the sea ice will become our friend once on we reach
 our oceanographic stations because it calms the seas, allowing our sampling
devices (such as box cores, megacores and yoyo cameras (picture below) to
 work at high efficiency.

We have just entered the fast ice – a featureless plain stretching white
 to the horizon. The scraping and growling begins anew! We hope Poseidon
 allows us to pass through the sea ice to our stations!!

The intrepid Yoyo Camera being lowered into the ocean in
Barilari Bay. This camera is raised and lowered (or "yoyo-ed") near the
seafloor, allowing the lead weight on the end of the line to trip the
camera. In this way, we get about 100 high quality pictures of the 
seafloor and its denizens over a distance of about 1 km (see picture a few posts earlier).

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