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Antarctic roadblock: icebergs, beautiful and lethal

Our theme for today is ice. Big ice.

We left our southernmost sampling area at Charcot Island and headed north toward Marguerite Bay, with a scheduled stop in a small bay named Lazarev to look for Adelie penguins and sample for silverfish. We were stopped in our tracks by a fleet of icebergs.

To say that icebergs are a hazard to navigation is severely understating the case; even strong icebreakers like the Palmer would not survive a close encounter with a berg.

Up until last year, Charcot Island and the next island north along our track, Rothschild, were joined to the Wilkins Ice Shelf.

On the Google Earth map (a 1999 image), the ice shelf is in place and Charcot and Rothschild are faintly outlined in gold ink. The islands are almost indistinguishable from the ice.

In 2001, Bill Fraser, our penguin biologist, and I had visited Lazarev Bay and it was nearly clear of icebergs. The Wilkins Ice Shelf, at the southern end of the bay, was intact.

Ice shelves are essentially large floating glaciers. They are continuous with the land or landfast and are fed by glaciers. When they break up, they can create tabular icebergs the size of several football fields placed end to end.

As icebergs age, they melt from beneath, turn over, and assume different shapes. (Our photographer in residence, Paul Suprenand, has captured many of these floating works of art for you.)

The Wilkins shelf, deteriorating for the past several years, finally broke up in 2009. And now Lazarev Bay is full of bergs, beautiful and lethal.

•••

It's getting colder (about 18 degrees Fahrenheit), the days are shorter and the winter sea ice is beginning to form in earnest. So we are seeing more and more larger animals that use the sea ice for a floor. In one of the photos you can see a fur seal on an ice floe with some crabeater seals. See any difference? In our next few dispatches, we will show you more Antarctic marine life as we continue in our quest for silverfish.

Antarctic roadblock: icebergs, beautiful and lethal 04/02/10 [Last modified: Friday, April 2, 2010 12:31pm]

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