The oceans are getting noisier, and that’s bad news for whales, dolphins, and sea turtles who use sound to communicate and navigate, researchers declared at a United Nations wildlife conference. Rumbling ship engines, seismic surveys by oil and gas companies, and intrusive military sonars are triggering an “acoustic fog and cacophony of sounds” underwater, scaring marine animals and affecting their behavior. “There is now evidence linking loud underwater noises with some major strandings of marine mammals, especially deep diving beaked whales” [Reuters], says Mark Simmonds of the Whale and Dolphin Conservation Society.
Researchers have long worried that high-powered sonar pulses confuse whales and dolphins and may cause the animals to beach themselves. Marine mammals are turning up on the world’s beaches with tissue damage similar to that found in divers suffering from decompression sickness. The condition, known as the bends, causes gas bubbles to form in the bloodstream upon surfacing too quickly. Scientists say the use of military sonar or seismic testing may have scared the animals into diving and surfacing beyond their physical limits, Simmonds said [AP]. He points to two recent strandings as possible results of the noisy waters (although a link has not been proved): the 100 melon-headed whales that were found on a Madagascar beach, and the two dozen dolphins that got stranded in southern England.
The current U.N. conference is considering a resolution that would oblige countries to reduce sound pollution. Other suggested measures include re-routing shipping, cutting speed and banning tests and sonar use in the habitats of endangered animals…. A spokesman for the UN Environment Programme said governments seem ready to take action to alleviate the problems caused by noisy oceans. [BBC News]. However, whale conservationists had a recent setback in the United States, where the Supreme Court ruled in favor of allowing the Navy to conduct military exercises using high-powered sonar.
A study published this fall also found an indirect cause of noise pollution: global warming. Researchers found that rising levels of carbon dioxide are increasing the acidity of the Earth’s oceans, making sound travel farther through sea water. The study by the Monterey Bay Aquarium Research Institute … shows the changes may mean some sound frequencies are traveling 10 percent farther than a few centuries ago. That could increase to 70 percent by 2050 if greenhouse gases are not cut [AP]. Animals like humpback whales that “sing” to each other during mating season may be having trouble finding each other, researchers said, as marine noise is drowning out their songs.
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Image: flickr / nestor galina