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ARI SHAPIRO, HOST:
Many animals that live in the ocean communicate with sound, like this humpback whale.
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SHAPIRO: But these voices could soon be drowned out by powerful sonic booms set off in the ocean by energy companies. The Trump administration is opening up the Atlantic coast to oil and gas exploration. Biologists say just the process of looking for undersea reservoirs could threaten ocean life, as NPR's Christopher Joyce reports.
CHRISTOPHER JOYCE, BYLINE: There's a human-made sound that dwarfs all others in the ocean - the boom of seismic air guns.
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JOYCE: Five companies plan to use air guns to survey thousands of miles of seabed along the Atlantic coast. That could start later this year. The air guns are towed behind the ship. They compress and then release air explosively, and the sound waves penetrate the seabed to reveal reservoirs of oil and gas. Ships have to turn them off if they see whales or other marine mammals nearby. The sound blasts can damage the ears and internal organs of animals. But scientists are increasingly concerned about less obvious effects of air guns well outside the immediate danger zone. Aaron Thode is an oceanographer who studied the effects of air guns.
AARON THODE: We don't know what would happen if animals were exposed constantly to sound over long periods of time in, say, a feeding area, a breeding area or whatnot.
JOYCE: Thode works at the Scripps Institution of Oceanography. He says whales have been observed retreating from the sound of air guns. That could cause them to abandon breeding or feeding grounds. Thode has also discovered that bowhead whales start calling more often to each other when there's air gun noise, at least for a while.
THODE: At some point, you know, just as if a jet plane passes overhead, you'll just kind of give up and wait for the sounds to decrease.
JOYCE: Whales and dolphins and even fish signal each other with sound. Marine biologist Doug Nowacek at Duke University worries that air guns could overwhelm that communication that could cause a mother, for example, to lose its calf.
DOUG NOWACEK: So if they get separated by a few tens or hundreds of meters in an increasingly loud ocean, you can consider it gone.
JOYCE: Nowacek says new evidence shows animals can be a long way from the air guns and still be affected.
NOWACEK: The levels that could still have and do have behavioral impacts extend out tens to hundreds of miles away from those surveys.
JOYCE: And effects on smaller animals are emerging as well. Research in Australia shows that air guns can actually kill shrimp-like plankton. Moreover, the sound is pervasive. Surveyors fire the air guns several times a minute for months at a time. Interior Secretary Ryan Zinke described the energy plan at a press conference last January. He promised that the government will protect the environment.
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RYAN ZINKE: We do it right. And we're not going to skirt protections. We're not going to give anyone a pass. We're going to hold corporations accountable.
JOYCE: The Interior Department completed an environmental impact study on seismic surveying in 2014. It says the effects on marine life will be moderate at worst. They point out that surveyors will stop their work if they see or hear whales within 500 yards and will keep away from places they're known to frequent. But more than 70 scientists have written to President Trump asking him to cancel the surveys anyway. They note that the blasting covers regions populated by several kinds of whales that are in danger of extinction. Doug Nowacek is one of those scientists.
NOWACEK: There are numerous species off the Atlantic coast that have never been - we don't have any data whatsoever about their response to seismic.
JOYCE: The Interior Department is expected to rule on the surveying permits in the next few weeks. Environmental and other interest groups are preparing to legally challenge any permit to allow seismic testing. Christopher Joyce, NPR News.
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