Noise Called a Serious Threat to Sea Creatures

An invisible form of pollution is permeating our deepest oceans, posing an insidious threat to whales, seals and other sea creatures, a new report warns.

The threat is underwater noise from supertankers, oil exploration and new military sonar that could fundamentally alter the ocean habitat, says the report from the Natural Resources Defense Council. It warns that underwater noise can wreak havoc with the creatures’ natural communications systems and force whales to deviate from their migration routes.

The report, to be released Monday by the environmental group, offers no conclusive new evidence of widespread harm. Rather, it calls for more investigation of how noise affects sea creatures and for stiffer regulations to protect them--including, perhaps, a law regulating ocean noise like the Clean Air Act attempts to curb smog.

It notes that in dark sea waters, mammals such as whales and porpoises appear to use their hearing much as humans use sight to seek out food, find mates, guard their young and avoid predators.

“We’re playing Russian roulette with our oceans, and we can’t afford to do that,” said Joel Reynolds, senior attorney with the council.

Some experts who have reviewed the report say that although they may disagree with some criticisms and conclusions, they concur with its findings about the urgency of ocean noise pollution.

“It is a serious problem. The problem is, we don’t know how serious it is,” said Roger Gentry, acoustics team coordinator for the National Marine Fisheries Service, which oversees most marine life in U.S. waters. He called the report “a pretty fair summary” of the issues that acoustics experts--in government, the military, academia and the environmental movement--have grappled with as they learn more about how noise affects sea life.

Cornell University bioacoustics expert Christopher W. Clark compared the increasing sources of ocean noise to the visual effect of strip malls and electrical wires on dry land. His own studies have suggested that the effects of two high-profile ocean-noise emitters could be less dire than environmentalists feared. Still, he too urges caution.

“If you just went out and listened in the Channel Islands, you’d be appalled,” he said. “Those places off San Francisco, off Los Angeles--you’re just in the middle of an acoustics traffic jam.”

The study pinpoints several areas where high levels of underwater noise and abundant sea life coincide--including San Francisco, Monterey and San Diego bays and Santa Barbara Channel--where environmentalists want to see special efforts made to reduce noise.

One key issue is how man-made noise may harm marine mammals, especially since sound travels faster through water than air. Whales have been known to change direction while migrating to avoid noise and abandon their traditional breeding grounds, scientists say. But research is too new to say definitively whether these behavioral changes may harm mammal populations in the long term, said Clark and Gentry.

Just like humans, some marine mammals lose hearing from exposure to sounds. But still elusive is whether they suffer significant physical damage from man-made sound.

The noise report is being issued at a key moment for those studying ocean noise, with a lineup of national policy decisions in the offing.

Within weeks, the Navy is due to make public its draft environmental impact statement on a controversial new technology for detecting enemy submarines. Navy officials hope to deploy a new sonar system--known as low frequency active sonar--designed to be so sensitive that it can track newer, quieter submarines lurking in the ocean depths.

The new sonar would work by transmitting as much as 215 decibels of sound from underwater speakers, a prospect that alarms those fearful that ocean noise already could be harming some whales and other marine mammals.

The National Resources Defense Council has vehemently voiced concerns about how the system could affect sea creatures. The Navy agreed three years ago to seek outside scientists to research the effects of its system. Since then, research conducted in the Pacific indicates that its biological significance is minor, Navy officials say.

The Navy will hold four to five public meetings to explain the program, along with required hearings, said Navy spokesman Lt. Steven Mavica. “We want to do everything we can to allay the criticism and allay the fears.”

More noise-related battles could surface in coming months. Congressional hearings begin Tuesday on reauthorization of the Marine Mammal Protection Act, which mammal advocates view as their chief tool to fight noise pollution.

On another front, scientists will seek permission to continue a study in Hawaii in which underwater loudspeakers transmit low-frequency sounds to measure ocean temperatures. In 1995, plans for a related study off the Central California coast provoked a torrent of protest from environmentalists who accused the project’s operator, the Scripps Institution of Oceanography, of ignoring potential harm to marine mammals.

Although the California project fizzled amid the furor, Scripps reports that two years of tests in Hawaii of its project have revealed no significant effect on mammals.

While the Scripps and Navy projects have grabbed the public’s attention, the noise report notes that international shipping is the single biggest source of noise pollution--yet remains the least regulated noise polluter.

In fact, while scientist have applied for federal permits to perform noise research that may disturb marine life, “not one [application] has come from the massive supertankers and cargo ships that degrade our shoreline.”

Among recommendations in the noise report is a call for regulatory agencies to be granted the power to regulate the acoustic output of ships and other sources of noise. It suggests modeling new legislation after the Clean Air Act and the Clean Water Act, holding polluters to the lowest practicable emissions and setting targets.

Other recommendations include setting aside marine reserves to protect animals from noise, additional research and international standards.

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The Roar of the Ocean

Some environmentalists and scientists fear that artificially generating sounds underwater might interfere with communication among marine mammals. Two techniques, one for locating submarines and another for measuring global warming, are illustrated below: