The Great Barrier Reef off the coast of Queensland, Australia, in August 2009. Scientists say they have discovered a second, enormous reef in the deeper water behind the Great Barrier Reef.
Phil Walter/Getty Images
Staghorn coral planted by scientists in the Florida Keys. Researchers hope to give the same sort of boost to the world's shrinking population of pillar coral, now that they can raise the creatures in a laboratory.
Joe Berg/Way Down Video/Mote
These scuba divers are among the 2 million tourists who visit the Great Barrier Reef each year. They contribute about $5.6 billion to Australia's economy, according to the Queensland government.
Steve Dorsey for NPR
A tasseled wobbegong shark (top) lies on the seafloor with the head of a brown-banded bamboo shark in its mouth on the fringing reef of Great Keppel Island on Australia's Great Barrier Reef in August 2011.