Whales and dolphins depend on being able to hear their own much less powerful echolocation to feed, communicate and keep in touch with their family groups across hundreds of miles. Even fish and crabs navigate and communicate by sound, said Grant Gilmore, an expert on fish ecology in Vero Beach, Fla.
"We don't know what the physiological effects are. It could be permanent hearing damage in many of these creatures just by one encounter with a high-energy signal," Gilmore said.
More than 120,000 comments were sent to the government, which spent years developing these rules. The bureau's environmental impact study estimates that more than 138,000 sea creatures could be harmed, including nine of the world's remaining 500 north Atlantic right whales.
These whales give birth and breed off the coast of Florida, Georgia and the Carolinas.
"Once they can't hear -- and that's the risk that comes with seismic testing -- they are pretty much done for," said Katie Zimmerman, a spokeswoman for the South Carolina Coastal Conservation League based in Charleston, S.C.
"Even if there were oil out there, do we really want that? Do we really want to see these offshore rigs set up?" she asked.
By federal law, scientists can't approach marine mammals without following careful protocols, and yet this decision will pervade their environment with noise pollution that could have a long-term impact on their population, said Scott Kraus, a right whale expert at the John H. Prescott Marine Laboratory in Boston.
"No one has been allowed to test anything like this on right whales," Kraus said. "(The Obama administration) has authorized a giant experiment on right whales that this country would never allow researchers to do."
Some exploratory wells were drilled before the U.S. Atlantic seabed was closed to exploration in the 1980s, but they never produced much. The latest seismic technology should change that.
"One thing we find is, the more you get out and drill and explore to confirm what you see in the seismic -- you end up finding more oil and gas than what you think is out there when you started," Radford said.
More than 16 communities from Florida to New Jersey passed resolutions opposing or raising concerns about seismic testing and offshore drilling. In north Florida's St. Augustine Beach, tourism and fishing fuel the economy, and rare turtles come ashore to lay eggs.
"Florida has already felt the devastating effects of an uncontrolled oil release with the Deepwater Horizon event of which cleanup efforts are still on-going," said John Morris, a county commissioner whose constituency includes the beach town. "Any oil spill, large or small, off the coast of St. Johns County, would greatly affect the county's economy."
Associated Press Writers Bruce Smith in Charleston, S.C.; and Alex Sanz in Vero Beach, Fla., contributed to this story.
Jason Dearen can be reached at http://www.twitter.com/JHDearen