Giant iceberg decimates Antarctic penguin colonies
THE POPULATION OF Adélie penguins at Cape Denison in eastern Antarctica has crashed from more than 160,000 in 2011 to just a few thousands, following the grounding of a massive iceberg in Commonwealth Bay.
In December 2010, the giant iceberg – called B09B – with an area of around 2900 sq.km grounded in Commonwealth Bay after colliding with the Mertz Glacier Tongue.
According to research published this month in the journal Antarctic Science, the iceberg caused fast ice expansion in the region (floating sea ice that is permanent attached to land), which means the penguins have to walk more than 60km to find food.
Previously, the region was rarely covered by sea ice, making it an ideal place for Adélie penguin colonies. A large area of open water existed close to shore, making Commonwealth Bay the ideal location for Sir Douglas Mawson’s 1911-14 research station during his original Austalasian Antarctic Expedition.
“Heart-wrenching” impact
“Over the past five years the regional changes triggered by iceberg B09B have led to an order of magnitude decline in Adélie penguin numbers and catastrophic breeding failure in comparison to the first counts undertaken by Mawson a century ago,” said lead author Dr Kerry-Jayne Wilson of the West Coast Penguin Trust.
“It was heart-wrenching to see the impact of the fast ice on the penguins,” said Kerry. “The normally noisy and aggressive Adélie penguins were so subdued they hardly acknowledged our intrusion into their realm. It was sad to walk amongst thousands of freeze-dried chicks from the previous season and hundreds of abandoned eggs.”
By comparison, the researchers found an Adélie penguin colony on the eastern fringe of Commonwealth Bay, just 8km away, to be thriving – further indicating that the fast ice expansion was responsible for the decline.
However, the story isn’t all doom and gloom for the surviving penguins at Cape Denison.
“Over the last year the fast ice associated with B09B has begun to break up in Commonwealth Bay, which is great news for the penguin colonies,” said co-author Dr Chris Fogwill of the UNSW Climate Change Research Centre.
“However, the effects of the changes over the past five years we have observed on the ecosystems in and around Commonwealth Bay will help us better understand the impacts of such large scale events on the fragile Antarctic ecosystem,” he added.
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