WASHINGTON 鈥� Not only are humans changing the surface and temperature of the planet, but also its sounds 鈥� and those shifts are detectable even in the open ocean, according to research published Thursday.
Changes in the ocean soundscape affect wide swaths of marine life, from tiny snapping shrimp to huge right whales, the researchers found.
鈥淪ounds travel very far underwater. For fish, sound is probably a better way to sense their environment than light,鈥� said Francis Juanes, an ecologist at the University of Victoria in Canada and a co-author of the paper in the journal Science.
While light tends to scatter in water, he said, sounds travel much faster through water than through air.
Many fish and marine animals use sound to communicate with each other, to locate promising locations to breed or feed, and possibly to detect predators. For example, snapping shrimp make a sound resembling popping corn that stuns their prey. Humpback whale songs can resemble a violinist鈥檚 melodies.
But increased noise from shipping traffic, motorized fishing vessels, underwater oil and gas exploration, offshore construction and other human activity is making it harder for fish to hear each other.
The researchers sifted through thousands of data sets and research articles documenting changes in noise volume and frequency to assemble a comprehensive picture of how the ocean soundscape is changing 鈥� and how marine life is impacted.
Using underwater microphones, scientists can record fish sounds 鈥� which tend to hover around the same low frequencies as shipping traffic noise.
鈥淔or many marine species, their attempts to communicate are being masked by sounds that humans have introduced,鈥� said Carlos Duarte, a marine ecologist at the Red Sea Research Center in Saudi Arabia and co-author of the paper.
The Red Sea is one of the world鈥檚 key shipping corridors, full of large vessels
Meanwhile the overall number of marine animals has declined by about half since 1970. In some parts of the ocean, scientists now record 鈥渇ewer animals singing and calling than in the past 鈥� those voices are gone,鈥� said Duarte.
Climate change also influences physical processes that shape ocean sounds, such as winds, waves and melting ice, the researchers found.
鈥淚magine having to raise your kids in a place that鈥檚 noisy all the time. It鈥檚 no wonder many marine animals are showing elevated and detectable levels of stress due to noise,鈥� said Joe Roman, a University of Vermont marine ecologist, who was not involved in the paper.
鈥淲hen people think of threats facing the ocean, we often think of climate change, plastics and overfishing. But noise pollution is another essential thing we need to be monitoring,鈥� said Neil Hammerschlag, a University of Miami marine ecologist, who was not involved with the paper.
鈥淚f you make something for the ocean, think about how to make it quieter,鈥� he said.
Sound pollution may be simpler to address than other ocean threats, said the University of Victoria's Juanes. 鈥淚n theory, you can reduce or turn off sound immediately 鈥� it鈥檚 not like plastics or climate change, which are much harder to undo.鈥�
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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute鈥檚 Department of Science Education. The AP is solely responsible for all content.
Christina Larson, The Associated Press
