The residents of California’s Santa Monica Bay have some rather noisy neighbors—and they’re not happy about it. That is the conclusion of a new study which shows that blue whales feeding off the coast of California stop calling to each other when a nearby naval base powers up its sonar for training exercises.
It’s not exactly news that sonar can disturb whales. What’s different about this study, conducted by a team from the Scripps Institution of Oceanography at UC San Diego for the journal PLoS One, is that it shows an underwater sound outside a baleen whale’s vocalization range can still affect its calling behavior. (Baleen whales – which include the blue, humpback and right — emit deep bass notes well below the ping of sonar.) Because the endangered blue whale may depend on communication to keep its family group together and alert them to the presence of food, the effects of that sonar are a serious concern.
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“I was hearing ‘beep beep beep,’ sometimes for one hour or even two days,” said lead author Mariana Melcón, who monitored the giant creatures for two years while they summered in California. “This seems to be very annoying for them.”
But it’s not only sonar that’s getting to them. When ships come by, churning sound of the engines falls within the blue whales’ vocalization range, which means the creatures have to raise their voices. “It’s like we are talking and all of a sudden someone turns on the music very, very loud,” explains Melcón. “Either we continue talking and try to understand each other, or we talk louder.”
Unsurprisingly, this sort of effect – like living inside a noisy, dark bar – is not ideal for intelligent and social mammals trying to have a conversation. Earlier this month, a groundbreaking study came out which showed that when shipping clamour died down in the week following 9/11, the stress hormone levels in a population of whales off the coast of New England plummeted. While the rest of the world reeled, whales finally found some much needed peace and quiet.
This chronic stress, however, is usually hidden from human eyes. “The idea was they weren’t disturbed because they were just hanging out,” said Scott Kraus, the director of research at the New England Aquarium and an author on the paper. “You think, ‘Oh, nothing’s wrong.’ But in fact, there is something wrong.”
It’s not just about annoying whales and dolphins. To these animals, sound – whether a chronic drone or intermittent blast — can be a serious problem. It has behavioral effects, like driving cetaceans away from food, forcing them to breach or surface aburptly, or disrupting communication. (A male blue whale letting out a deep call to females off the coast of Canada could once be heard more than 1,500 miles away in the Caribbean. Today, his song travels only 50-100 miles, limiting the chances of finding a mate.) Then there are physiological impacts, from hearing damage to gas-filled lesions caused by a rapid, startled ascent—the cetacean equivalent of the bends.
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As evidence of undersea noise’s effect on whales and dolphins mounts, so is the total volume. Oil and gas exploration in the North Sea, which uses powerful blasts of low-frequency sound in seismic survey, is one threat. Even the drive towards renewable energy – like off-shore wind farms — can have its drawbacks. “It’s essentially pile-driving,” says Mark Simmonds of the Whale and Dolphin Conservation Society. “If you’re installing a thousand wind farms in a particular area, you’re going to be making a heck of a noise. And that noise can travel a long distance.”
Luckily it’s not all bad news. Technology can help — if people are willing to pay for it. Piles being hammered into the ground for wind farms, for example, can be surrounded by ‘bubble curtains,’ a wall of bubbles that stops the sound from traveling. And piles don’t necessarily need to be driven – they can be settled into a hole made with a quiet water drill, or merely anchored to the seabed. In terms of shipping noise, efforts are under way by the International Maritime Organization to develop and encourage the use of quieter engines on ships. “Noise is generally inefficiency in propulsion,” says Kraus. “In the long term, it may be a win/win situation.”
Even the U.S. Navy, long the bête noire of the whales’ sonic world, is now working on the problem of ocean noise. In fact, over the last ten years the U.S. Navy has been the primary funder of marine mammal research on the planet. “It took them a while,” says Brandon Southall, senior scientist for Southall Environmental Associates who is leading a new five-year Navy-funded study into marine mammals and sonar called SOCAL-BRS. “But you can’t say that they haven’t put their money with their mouth is.”
Some say this isn’t simply a conservation issue. It’s a moral one. Last month, a group of scientists and ethicists presented a ‘Declaration of Rights for Cetaceans’ to the largest science conference in the world, the AAAS meeting in Vancouver, Canada. The Declaration states that because of their intelligence and social complexity, whales and dolphins should be respected as non-human persons with a right to life. “We’ve had decades of work demonstrating what kinds of beings they are, what kind of brains they have,” says Lori Marino, a senior lecturer in neuroscience and behavioral biology at Emory University, whose groundbreaking work has shown that dolphins, like humans and great apes, can recognize themselves in the mirror. “It’s all based on upon empirical evidence. We no longer have to guess.” Science, it seems, is telling us how undersea noise is affecting whales and dolphins. It also may be telling us why we should do something about it.
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