LOS ANGELES — IT began as an arcane ocean experiment to enhance knowledge of the planet - in this case, the all-important phenomenon of global warming.
But it has since escalated into the biggest aquatic snit since ``Free Willy'' - dividing scientists and now engulfing the public.
The source of the rub: a taxpayer-financed proposal to broadcast sound waves under the ocean off Hawaii and California to gauge changes in sea temperature.
Backers hope to determine whether the temperature of the Pacific is rising as a result of global warming, with all the implications that would hold for understanding the ``greenhouse effect'' and its impact on Earth ecology.
But critics believe the noise, capable of being detected as much as 900 miles away, could deafen whales and cause widespread harm to marine mammals.
``It would be almost an acoustical holocaust for the oceans,'' says Maris Sidenstecker, a marine biologist with Save the Whales.
The controversy highlights an unusual collision over environmental values: protecting marine life versus learning about a phenomenon that, project sponsors argue, could some day bring real harm to aquatic life.
Refereeing the dispute is the National Marine Fisheries Service, which must approve permits to allow the experiment, scheduled to start this spring, to go ahead. Under pressure from environmental groups, lawmakers, and others, the agency has decided to hold off making a decision until more public hearings can be held.
The one, and initially only, scheduled set of hearings was held last week in Maryland. But on Friday, the agency announced that two other public-comment sessions will take place, in California and Hawaii.
The clamor has caught the attention of members of California's congressional delegation, who are urging the Fisheries Service to proceed with caution on the permit.
The plan calls for placing two sets of loudspeakers about 2,800 feet underwater, one off Big Sur in California and another off the coast of Kauai in Hawaii. Sound would be broadcast every four hours for 20 minutes during the experiment, which initially is planned for two years but which scientists hope to extend until 2004.
The noise would be played at 195 decibels, which is high on the volume knob, but at a low frequency (75 hertz). The result, according to sponsors of the project at the Scripps Institution of Oceanography in San Diego, would be a low rumble generally inaudible to a human ear and perhaps even to many marine mammals.
The only creatures affected, they argue, would be mammals that come within a few hundred feet of the loudspeakers - and then the effects would likely be subtle. A whale might experience a temporary loss of hearing, if very near the source. To them, the sound would be little more than an oboe in the cacophony of noise that permeates the ocean - from ships, earthquakes, and other sources.
``We will not deafen a single marine mammal,'' says Andrew Forbes, deputy director of the project. ``A whale would discover it as just another natural sound in the ocean.''
ENVIRONMENTAL groups and some scientists, however, worry the drone will damage the hearing and affect feeding, mating, and migratory habits of acoustically sensitive mammals, including whales, dolphins, and seals. They wonder what the impact will be on fish and other marine life.
By their own account, sponsors estimate the project will affect 667,000 marine mammals, though only minimally. But critics point out the speakers would be placed in areas containing several species of threatened or endangered aquatic life.
``The scope of the project and the potential for harm is nothing less than spectacular,'' says Joel Reynolds, a senior attorney with the Natural Resources Defense Council.
The NRDC wants an environmental-impact statement done before the project goes ahead - and threatens to sue if one isn't.
Project scientists say that's what their initial two-year research program is intended to do - gather data and help determine impacts. They vow to halt the plan if harm is being done.
The idea behind the project, in effect, is to turn the ocean into a giant thermometer. Scientists would monitor the time it takes each broadcast to transit the ocean. Since sound travels faster in warmer water, researchers say they will be able to plot temperature changes in the ocean over a long period of time.
Global-warming research had focused more on detecting long-term changes in atmospheric temperature. But that's difficult, given daily and seasonal climate fluctuations. By measuring heat content of the oceans, researchers say they'll be able to learn more about global climate changes over the 10-year period of the project than other methods might yield in decades.
As part of their experiment, sponsors eventually want to dot the oceans with dozens of loudspeakers.
Whether their 20,000 decibels under the sea ever comes about, however, will depend on how much political noise the initial two-year research phase raises.