NAGS HEAD, North Carolina - The boom of seismic cannons will soon sound under the Atlantic Ocean. The first oil and gas exploration allowed off the East Coast in three decades will get underway as early as next spring.

Federal officials and the oil and gas industry say the exploration is harmless. Nags Head Mayor Bob Edwards disagrees. Edwards is terrified about what the intense sound waves can do to dolphins and endangered North Atlantic right whales, of which only 500 remain.

"I just can't understand how anybody would propose something that's going to be ... endangering whales and dolphins and turtles and fish," he said.

Disrupting Animal Behaviors

The seismic surveys are done with compressed air guns. The blasts are repeated every 10 seconds or so for weeks at a time. Echoes from the blasts are used to produce three-dimensional maps. The maps help oil company geologists figure out if there are likely to be fossil fuels, like oil and gas, in the rock formations.

The government approved opening an area of the Atlantic Coast from Delaware to Florida for the seismic blasts. It said there "has been no documented scientific evidence" that they harm marine mammals. Even federal scientists are worried, though, about what the pulses of sound can do to the hearing and communication of whales and other marine life. They use sound to locate food and mates, and to keep track of their young.

"It's been pretty well documented that seismic surveys have disrupted animal behavior and animal communication," said Danielle Cholewiak, an acoustics researcher for the National Oceanic and Atmospheric Administration.

Oil And Gas Money Versus Tourism Money

Political leaders in North Carolina, South Carolina and Virginia lobbied President Barack Obama to approve the seismic testing to see how much oil and natural gas lies off the East Coast. They hope that Obama will allow offshore drilling that will result in jobs and money.

But in coastal towns that rely on tourism the idea of drilling into the ocean is hugely contentious. In North Carolina's Outer Banks, for example, visitors rent vacation homes for weeklong vacations and relax on wide golden beaches along the windswept Atlantic Ocean.

A spill would ruin the local tourism industry, said Paul Manning, who owns the Front Porch Cafe on the Outer Banks. His employees roast coffee and serve up mugs to tourists.

Jessica Weiss Taylor, who leads the Outer Banks Center for Dolphin Research, worries about the dolphins that swim off the coast.

The environmental group Oceana says the seismic blasts threaten to injure or kill thousands of Atlantic marine mammals and pose a threat to the area's fisheries. Oceana has launched a campaign calling on President Obama to reverse his approval of the exploration.

Overblown Fears?

Allen Burrus, a grocer in the town of Hatteras, said offshore drilling would bring economic benefits to the Outer Banks. He suspects the environmental fears are being overblown.

"I believe if they can prove that it hurts the mammals in the sea then they probably should not do it," Burrus said. "But if it's not hurting them, then why not?"

Government officials say that during whale migration they will restrict when the seismic cannons are fired. They will require onboard spotters and acoustic tests to detect marine mammals and shut down activities when they are too close.

The seismic exploration "should not cause any deaths or injuries to the hearing of marine mammals or sea turtles" if such precautions are followed, the officials said.

The American Petroleum Institute, which represents the oil industry, said the seismic blasts are safe and are being overly restricted by the government.

"Operators already take great care to protect wildlife, and the best science and decades of experience prove that there is no danger to marine mammal populations," the group said in a statement.

Atlantic Whales Are Different

George Ioup, a physics professor, has studied the effects of the seismic blasts in the Gulf of Mexico. He said there are many unanswered questions, but that whales and dolphins in the Gulf tend to operate at frequencies far higher than the sound waves from seismic cannons.

"They probably don't even hear them very well," Ioup said.

It's different in the Atlantic, though, Ioup said. Species of large Atlantic whales, including endangered right whales, operate at low frequencies and will hear the booms. An "extraordinary amount of caution" is needed if there's seismic exploration near spawning or feeding grounds of such whales, Ioup said.

Restrictions on where the blasts can happen would only be so effective because the blasts can be heard for more than 2,000 miles underwater, said Doug Nowacek, a professor of conservation technology.

"If there's a survey in Virginia you're going to hear it in southern North Carolina - easily," Nowacek said.

"Show Me The Evidence"

The waters off North Carolina could see a lot of activity. The National Science Foundation plans a seismic air gun survey off the state's coast this month and next to study the Earth's crust.

Nowacek said there has been far too little data collected on the impact of the seismic cannons. He dismissed oil companies' arguments that the booms are harmless.

"I would say show me the evidence that there's no harm," he said.