Beached Iceberg in Antarctica Reveals the Vulnerability of Ecosystems to Sea Ice Cover

A grounded, giant iceberg in Antarctica may have provided scientists with a real-life experiment that reveals the vulnerability of marine ecosystems to sudden changes in sea-ice cover. The findings could have major implications for the future of climate change.

In this case, an iceberg became stuck in Commonwealth Bay in east Antarctica. This event dramatically increased sea-ice cover in the bay.

"Understanding the ecological effect of changes in sea-ice is vital for understanding the future impacts of climate change, but it is impossible to manipulate sea-ice at the scale we need to conduct experiments," said Graeme Clark, the lead author of the new study, in a news release. "Luckily, the grounding of an iceberg in Commonwealth Bay in 2010 provided us with a perfect natural experiment to carry out research on this important issue. Historically, the winds coming down from the Antarctic ice cap have kept the bay free of sea-ice for most of the year. But since the massive iceberg got stuck, the bay has been covered in sea-ice several meters thick, all year round."

The researchers actually examined this area by drilling through the sea ice in the bay and using underwater cameras to survey the seabed.

"After three years of sea-ice cover, the forests of healthy seaweeds that previously dominated the seabed were in a severe state of decline," said Emma Johnston, one of the researchers. "About three quarters were decomposing, while the remainder were discolored or bleached. However, darkness-adapted vertebrates such as brittle stars and fan worms were starting to colonize the bay."

The findings reveal what a large impact sea ice can have on a region. Sea ice affects how much light reaches plants and animals living on the sea bed, and regulates the amount of disturbances from drifting icebergs that scour the bottom, and determines the amount of detritus and vegetation that settles there.

The findings are published in the journal Polar Biology.

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