Florida Reef System, why its important to care.

South Florida's corals are turning white and contracting fatal diseases in what's being called an unprecedented die-off across the region's reefs.

Although they cover a small fraction of the ocean floor, coral reefs have an outsize biological importance, providing habitat for about a quarter of the world's marine species. The southeast Florida reefs, which run from the Florida Keys through Martin County, constitute one of the region's major recreational areas and attract thousands of tourists for fishing, diving and snorkeling.

The bleaching and disease has struck around the world, with scientists blaming global warming, as well as unusual weather events, including the warming of the Pacific Ocean called El Niño. Last week scientists announced that 93 percent of the Great Barrier Reef in Australia had been affected.

"We've never seen anything like this scale of bleaching before, said Terry Hughes, director of the Centre for Excellence of Coral Reef Studies at James Cook University. "In the northern Great Barrier Reef, it's like 10 cyclones have come ashore all at once."

The National Oceanic and Atmospheric Administration said the global bleaching is likely to last into 2017.

dfleshler@sunsentinel.com, 954-356-4535