It's an idea that was ignored by the previous generation of fisheries managers, he said, which is one reason so many marine fisheries are in trouble today.

On the other hand, Ogden says overfishing, like that which removed the groupers from the Bahaman reefs, is only one of the "big three" factors affecting fisheries and reefs worldwide. The other two are land-based pollution reaching the oceans and global warming.

The pollution that causes the most trouble is run-off fertilizers and sewage that cause plankton blooms, which suck up oxygen from the water, creating vast, putrid marine "dead zones" like that found where the Mississippi River empties into the Gulf of Mexico.

Global warming, for its part, is gradually raising water temperatures and stressing coral reef organisms, Ogden explained. It could even have been a factor in, or at least is analogous to, the sudden unexplained die-off of the Caribbean sea urchins, he said.

"It's entirely possible that the accumulation of stress allowed what was otherwise a harmless organism in the (skins) of sea urchins to become pathogenic," Odgen said.

As for how the Bahamas study reflects other reefs worldwide, Mumby said it depended on how many seaweed grazers there were at a given reef.

In the Pacific Ocean, for instance, coral reefs have many kinds of grazers, so it's less likely that the demise or re-introduction of one species or grazer or predator would cause as dramatic an effect.

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