Humans are changing the way the ocean sounds, and it is having a profound impact on marine life.
A major new literature review published in Science on Thursday found that noise from vessels, sonar, seismic surveys and construction can damage marine animals' hearing, change their behaviors and, in some cases, threaten their ability to survive.
"When people think of threats facing the ocean, we often think of climate change, plastics and overfishing," Neil Hammerschlag, a University of Miami marine ecologist who was not involved with the paper, told The Associated Press. "But noise pollution is another essential thing we need to be monitoring."
Sound is key to how ocean animals communicate with each other and navigate their environments. Underwater, it is only possible to see for tens of yards and to detect a chemical signal from hundreds of yards away, The New York Times explained. Sound, on the other hand, can travel thousands of miles, which is why many marine creatures have evolved to detect and emit it.
However, the singing of whales and groaning of coral reefs contribute to an underwater soundscape that is significantly changing because of human activity. To better understand, a 25-author research team reviewed more than 10,000 papers on the topic.
For one, the researchers wrote, overfishing and habitat loss have decreased the sounds generated by ocean life.
"[T]hose voices are gone," Carlos Duarte, study lead author and Red Sea Research Center marine ecologist, told The Associated Press.
The climate crisis is also altering sounds from geophysical sources such as sea ice and storms, the study found.
Then there is the noise humans have added through shipping traffic, fossil fuel exploration and even intentional attempts at deterrence. Evidence shows that these noises harm marine mammals, but several studies show that they impact fish, invertebrates, sea birds and reptiles as well.
For example, salmon farms in British Columbia's Broughton Archipelago installed sonic harassment devices to keep seals from eating the fish, The New York Times reported. This had the unintended consequence of driving away killer whales until the devices were removed.
Another example are clownfish, who rely on sounds to guide them back to the coral reefs where they were born, after drifting on the open ocean as larvae. But human-caused noise can now obscure the cracking and snapping of coral, forcing some clownfish to drift forever.
"The soundtrack of home is now hard to hear, and in many cases has disappeared," Duarte told The New York Times.
While this is distressing, the good news is that something can be done about it. Noise is what is known as point-source pollution, the study explained, meaning you can identify the place or activity that is causing the problem and remove it, reversing its effects.
"In theory, you can reduce or turn off sound immediately — it's not like plastics or climate change, which are much harder to undo," Francis Juanes, study coauthor and University of Victoria ecologist, told The Associated Press.
Despite this, noise is not mentioned in the UN's Law of the Sea B.B.N.J. agreement or its 14th sustainable development goal, which focuses on ocean life, The New York Times reported. Researchers hope that their work will inspire policy makers to take ocean noise seriously and deploy already available solutions.
"Slow down, move the shipping lane, avoid sensitive areas, change propellers," Steve Simpson, study co-author and University of Exeter marine biologist, told The New York Times.
(Sources: EcoWatch)
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