Philippe Cousteau, president of the environmental advocacy group EarthEcho International, said growing coral in captivity is "very cutting-edge stuff . . . there are only a few people doing it." Coral reefs, including Australia's noted Great Barrier Reef, sustain much of the world's tropical-sea ecology. Reefs not only house a third of all marine species, but also anchor soil to prevent underwater erosion and produce algae that form the base of oceanic food pyramids. Coastal development, increased pollution in rivers that empty into oceans and commercial activities such as fishing and snorkeling have endangered more than three-fourths of the world's coral reefs, ecologists estimate. This has spurred worldwide efforts to preserve them.