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WHOI scientists to study underwater noise from turbines

How will the 130 wind turbines at the off-shore Cape Wind project change the underwater noises for marine animals in Nantucket Sound? Although the environmental impacts of Cape Wind have been reviewed, less attention has been paid to how the sounds of the construction and operations of the turbines will impact the marine environment, said T. Aran Mooney, a marine biologist at Woods Hole Oceanographic Institution.

Now Dr. Mooney and his colleagues are working to under- stand the impact of the off-shore wind turbine project with an ongoing experiment that he believes to be the first of its kind in the United States.

For the past six months, Dr. Mooney has recorded the marine “soundscape” at the site using sensitive underwater microphones. The ocean sounds include waves and rain on the surface, noises from fish, cusk eels, dolphins and whales, as well as man-made sounds from boats, scientific sonar, and construction.

So far the site is relatively quiet, he said, with most of the sound coming from recreational and commercial vessel traffic in the area. But the marine animals can make noises too. “Fish are really noisy,” Dr. Mooney said. Cusk have a distinctive chatter and Cod make knocks and clicks, which can be distinguished from the whistles and clicks made by dolphins and porpoises.

In March Dr. Mooney and WHOI biologist Laela Sayigh began recording the underwater noises in the 25-square-mile area between Nantucket and Cape Cod where Cape Wind plans to put 130 440-foot-high turbines. Using digital acoustic monitoring instruments anchored to the ocean bottom, they are measuring and identifying all underwater sound at the site. They plan to continue recording before, during, and after construction which is expected to begin next year. The experiment will continue at least through the next
year and a half to monitor the changing sounds.

Once construction begins, the sounds should change dramatically, he said. When the turbines start turning the longer duration lower amplitude noises could also affect marine life, but exactly how is uncertain. The steady operation of turbines will generate continuous noise, perhaps at the frequencies used by marine mammals or fish. “In some people it can cause chronic stress,” Dr. Mooney said, but marine life might react differently. Many marine animals and larvae are attracted to sounds in the ocean so the turbine sounds may actually bring larvae in, he said. The turbine structures could also become an artificial reef so there is also a potential benefit for marine animals.

Although Dr. Mooney is aware of the controversy surrounding the Cape Wind project, it is his goal to remain neutral while studying the underwater sounds. “We’re trying to work well with everybody,” he said.

Dr. Mooney, 34, is from Albany, New York, originally and has been working at WHOI and living in Falmouth since 2009.