Researchers from Woods Hole Oceanographic Institute have begun a 2-3 year project that will monitor the soundscape at the Cape Wind site before, during, and after construction of the planned 130 wind turbines. This is the first time such a long-term acoustic monitoring study has taken place at an offshore wind site.
“We want to evaluate the importance of this kind of research for future offshore wind farm development, which is a rapidly growing field of interest in the U.S.,” Aran Mooney said. He and his colleagues are outlining a methodology for how acoustic monitoring may occur in other wind farm construction. Mooney said, “That will be valuable for industry, policymakers, and the public.”
Two kinds of acoustic recorders are being used: one records the full range of frequencies continuously for a week at a time; the other samples one minute of sound every ten minutes for 2-3 months, at frequencies up to 40kHz (thus missing echolocation clicks but capturing most other vocalizations of interest). “So we’re making the best of both worlds, putting one device out to get a really in-depth look for one week, and then we continue with the other device to get a sampling period of several months, then we replace both,” Mooney said.
During wind farm construction, pile driving will add significantly to existing human noise in the area; at European wind farm sites, some species tend to move as far as 20km away during construction. During operation of the wind farm, noise is not expected to be audible at distances more than a few tens or hundreds of yards, but this study will help to quantify exactly what frequencies are propagating into the waters.
Mooney would like to see the project also contribute to a growing research focus on using sounds to monitor overall environmental health of various habitats. “Animals make sounds when they attract mates or reproduce, and you can track those activities just by listening,” Mooney said. “What I’d love to do with this project is to look at biological diversity. In a nice healthy habitat, you have a spectrum of sounds: low-frequency sounds of fish, then invertebrates a little bit higher, and then the seals and the dolphins.” The soundscape of an undersea area under an environmental stress would sound different; the impacts could be assessed by listening to what’s missing, for example.
For more on the project, see this page on the WHOI website, which also includes recordings of more than a dozen species of ocean creatures.