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TRANSCRIPT
Emily Dieckman: Picture this. Or, rather, listen to this: You’re a dolphin, in the Hauraki Gulf off the coast of New Zealand, swimming on your merry way, surrounded by the clicking of snapping shrimp scurrying along the seafloor. Sound, not sight, is your primary sense. It’s the way you get around, find food, and communicate.
And then you hear this:
[sound clip of the drone of boat engines heard from underwater]
That’s the sound of the 36th America’s Cup held in New Zealand in March 2021, as heard from underwater. The sailboats competing in the regatta didn’t cause much noise. After all, they’re not motorized. The racket came from spectator boats.
A new study used hydrophones, which are basically underwater microphones, to find out just how noisy the event was. America’s Cup is the largest competitive sailing event in the world. Each day, up to 1,300 vessels traveled to and from the race course to watch the event.
Matt Pine is the director of Ocean Acoustics Ltd in New Zealand and honorary research fellow at Heriot-Watt University in Edinburgh. He specializes in bioacoustics research and led the study. He said all this noise affects the creatures living in the water.
Matt Pine: Everything’s soniferous. So it’s a very sonic world. So when we have what we call anthropogenic noise coming in, instead of it being nice and quiet, it’s sort of like a fog.
Dieckman: This fog prevents the animals from talking to each other. Pine used the example of marine mammals, like a mother and a calf, who might be briefly outside of one another’s visual range because they’re feeding.
Pine: And when you get this haze coming in, whether it’s passing boats or construction or just, you know—anthropogenic noise is just noise made by humans—it gets very stressful for the mother. They freak out because obviously they can’t be in communication with the calf. The calf panics. So you get kind of those stressors, stress responses, which are not good.
Dieckman: Lucille Chapuis, a marine bioacoustician at the University of Bristol who was not involved in the research, said some marine life needs the quiet.
Lucille Chapuis: Animals use sound to find preys, to avoid predators, or to find reproductive partners. So if you mask that with noise, there’s a lot of missed opportunities.
Dieckman: To measure how loud large regattas like America’s Cup can get, the researchers recorded the underwater sound levels before, during, and after the event. They knew, of course, that more boats on the water would generate more sound. But the researchers were surprised by how far the sound carried. Here’s Emily Hague, a marine conservationist at Heriot-Watt University studying how human activity affects marine mammals. She’s another coauthor of the paper.
Emily Hague: But, interestingly, the noise goes further away than we were expecting. So I think the furthest away hydrophone we had down there was about 8 kilometers away, and it was still pretty noisy out there. We didn’t have a hydrophone farther away, so we don’t actually know how far it would have been until the noise levels went back to ambient levels.
But also, the noise levels were extended for longer than the race itself. So lots of noise as the boats are going out to go and see the event, and then afterwards when the event’s finished and they’re all heading back in.
Dieckman: On a typical race day, the hydrophones recorded mean ambient sound pressure levels about 5 underwater decibels higher than on a control day. Note that underwater decibels are not the same as above-water decibels because sound travels differently through air than it does through water. This increased noise level for most of the day comes despite the fact that racing only occurred for 2 hours in the afternoon. And many of these noises were at the same frequencies as dolphins use to communicate. Chapuis said this study matters because marine noise pollution can have such wide-ranging effects. Sometimes, they can even be deadly.
Chapuis: Yeah, it’s important because we know that noise can affect all animals at multiple levels. When I say all animals that we have studied, so it’s invertebrates, fish, marine mammals, seabirds, marine reptiles. And we know that noise can alter their behavior. It can harm their physiology and even affect their survival.
Dieckman: The researchers said the idea behind this study was to illustrate that this is an issue.
Hague: So it was it was super cool to see, I guess, all laid out as data. Because that’s kind of your ticket to prove to people that this is or could be a problem if we keep holding events in places that are important for marine wildlife.
Dieckman: Hopefully, the researchers say, this work can also help start a conversation about how to mitigate marine noise. That could mean asking spectator boats to turn off their engines when they’re not moving or having spectator boats enter in stages or at lower speeds. It could also mean being more aware of marine environments when selecting locations for events. Hague said she and her colleagues have been pleased to see that the sailing community and event organizers are engaged and looking forward to finding new solutions. There are already regulations about, say, throwing litter in the ocean or introducing invasive species.
Hague: But underwater noise has been kind of late to the party in terms of being considered.
Dieckman: Thank you to Matt Pine, Emily Hague, and Lucille Chapuis for speaking with me for this story. I’m Emily Dieckman. You can find a transcript and a reading list for this article at Eos.org, your source for Earth and space science news.
Music by artbybigvee via Pixabay.
—Emily Dieckman (@emfurd), Associate Editor
Citation: Dieckman, E. (2024), Sailing spectators’ sounds could harm marine creatures, Eos, 105, https://doi.org/10.1029/2024EO240466. Published on 18 October 2024.
Text © 2024. AGU. CC BY-NC-ND 3.0
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