NEW YORK: Glaciologist Erin Pettit began a research project to find out what humpback whales hear when a large piece of ice falls from a glacier and crashes into the ocean. But the sound generated by ice drifting in the water proved to be just as interesting.
Acoustic research in Alaska’s Icy Bay and other glacier ice-filled waters found that the fizz created by the release of pressurised air bubbles within glacier ice makes fjords the noisiest places in the ocean. ‘The glacier fjord sound on a typical day for Icy Bay is louder than being in the water beneath a torrential downpour, which really surprised me,’ said Pettit, a researcher at the University of Alaska Fairbanks.
In a paper published in Geophysical Research Letters, a journal of the American Geophysical Union, Pettit and fellow researchers speculate that one reason harbour seals flock to fjords is because noisy icebergs provide acoustic camouflage, protecting them from transient killer whales that hunt by sound. In July 2009, the researchers deployed underwater microphones 70 metres deep in Icy Bay, a fjord near the top of the Alaska Panhandle. They also sampled sound at nearby Yakutat Bay and at Andvord Bay in Antarctica.
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