Thirteen feet below the surface of Woods Hole harbor, a lobster shelters under a plastic shield in a wire cage. An experiment is happening: every seven seconds on the dock above, a pile driver pounds a long, steel post deeper into the muddy harbor bottom nearby.
Each strike creates an underwater boom.
Above the water, the noise is even more piercing. Andria Salas, a marine biologist from the Woods Hole Oceanographic Institution (WHOI), spends the day with ear protection always at the ready.
Part of her job is to handle the 50-odd lobsters involved in the experiment. She’s collecting data about the animals’ heart rates and movements every time the pile driver strikes.
To do that, she must outfit each lobster with a specialized tag.
“It’s a lobster saddle,” she says, demonstrating how the tags are strapped around a lobster’s middle.
Salas says she woke up with the idea for the wearable tags. Each one is made using a snorkel mouthpiece, custom circuit board, and Velcro belt.
“It’s worked pretty well,” Salas says. “We’ve never had one fall off.”
Aran Mooney, the lead scientist on the project, puts it this way: “They’re basically Fitbits for lobster.”
Read all of CAI’s reporting on offshore wind here
The experiment happening here at this dock is designed to replicate, at small scale, the pile driving necessary to construct an offshore wind farm.
The goal is to understand how a variety of marine creatures — not only lobsters, but other fish-market-friendly species like scallops, flounder, black sea bass, and squid — respond to the noisy, intensive work of building an offshore wind farm.
It’s something fishers and regulators are especially interested in.
“No one’s analyzed lobster heart rate data in respect to sound exposure or these stress responses,” Mooney says. “So this is kind of completely new.”
More research needed as offshore wind industry faces challenges
The steel pole Mooney’s team uses is only one foot in diameter, compared to massive 30-foot-wide piles used by offshore wind developers. But the data the team is gathering can be scaled up, Mooney said.
“Being 5 or 10 meters away from our piling here is the equivalent to being about 200 or 300 meters away from an offshore wind farm [under construction, as far as] the sound levels that you would receive,” Mooney said.
This experiment is funded by the federal Bureau of Ocean Energy Management. It comes at a time when the offshore wind industry faces numerous challenges, including rising costs and a skeptical president-elect. At a rally in May, Donald Trump vowed to end offshore wind on “day one” of his second term.
For his part, Mooney said he’s not working for — or against — offshore wind. He’s a scientist studying animals; for him it’s all about tracking heart rates and signs of stress.
“We don’t know if these lobsters are responding to sound,” he said. “We don’t know if that response is negative. It could be positive. Or it could be no response at all.”
Underwater species show mixed response to pile-driving noise
Already, the WHOI team’s earlier studies have shown that squid, which detect sound through vibration, responded dramatically to pile-driving noise — at least, at first.
“They ink, they jet,” Mooney said. “They color-change and respond to this noise. But they habituate quickly. They’re not getting deafened, and they kind of go back to their normal behavior of feeding and trying to mate really quickly. So with that data, you can kind of say, ‘Okay, I think the squid fishery is probably going to be okay.’”
But it’s a different story for scallops, one of the highest value fisheries in the U.S. As soon as scallops were exposed to pile driving noise, they clammed up.
“[With] every strike, they close a little, and then they try and open, and they close a little, and then try and open. And they don’t habituate to that sound,” Mooney said. “That’s very, very exhausting for the scallop.”
As far as lobsters go, Salas said they may find that the noise is making the crustaceans’ hearts skip a beat.
“We’re looking at things called cardiac pauses that crustaceans can have,” she said. “They can do that when they sense something in their environment is startling or a stressor.”
Earplugs for lobsters? Scientists look for sound mitigation ideas
Offshore wind developers are already aware of problems that construction noise may create for marine life. To absorb pile-driving sound and protect whales, Vineyard Wind is using “bubble curtains” — walls of air bubbles, released from the ocean bottom. It’s a good start, Mooney said, but not targeted for the entire ecosystem.
“A lot of the mitigation measures are not designed for animals on the bottom, the fishery species that are detecting the vibratory component of sound,” he said. “That’s really just so fundamentally different.”
The WHOI team ultimately hopes to identify best practices to make construction noise less harmful to the bottom-dwellers. For instance, they’re looking at how lobsters respond when the pile driving is ramped up slowly.
Analyzing the data they collected will take about a year. The researchers hope to be back here in Woods Hole Harbor, running more experiments — and wearing ear protection — next fall.
Copyright 2024 CAI
