Hot oceans, loud shrimp It's loud, and getting louder, under the sea. Noise from ship traffic off the California coast has roughly doubled in volume each decade since the 1960s. Human-made sounds stress out whales. And as the oceans warm, a curious source of noise may increase, too — the violent snap of the pistol shrimp. Of all the things to squirm and swim under the ocean, snapping shrimp are among the loudest. They shut their claws shut so speedily the motion creates an unstable air pocket, which implodes with a pop. Some shrimp, as Wired notes, use these forceful snaps to drill into rock. Two marine biologists at Woods Hole Oceanographic Institution, T. Aran Mooney and Ashlee Lillis, are studying how the sounds of the shrimp change with ocean temperatures. They've found that the hotter the water, the more the shrimp snap. "We can actually show in the field that not only does snap rate increase, but the sound levels increase as well," said Mooney, who is presenting the research Friday at the American Geophysical Union's Ocean Sciences Meeting, in a statement. "So the seas are actually getting louder" as water temperatures rise. Oceans absorb more than 90 percent of excess climate change heat, and the seas are warming about 40 percent faster than the United Nations Intergovernmental Panel on Climate Change had predicted, The Washington Post reported last year. In laboratory tests, the shrimps snapped more than twice as many times in high-temperature environments as in moderate ones (comparing 86-degree v. 68-degree Fahrenheit conditions). These observations confirmed field recordings of snapping shrimp in the Caribbean and the Atlantic. Mooney said the increased shrimp snaps are loud enough they could confuse fish communication — fish, you may be surprised to know, can communicate by croaks, vocalization or drumming sonic muscles. It's even possible the shrimps' crackles could disrupt sonar, Mooney said. You can listen to the shrimp din here. |
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