NEW YORK — The U.S. government said Thursday it would list two coral species as "threatened" under federal species protection laws after damage to them increased last year as the Caribbean warmed to record levels.

The two species, Elkhorn and Staghorn coral, are threatened by bleaching, caused by high temperatures; disease; and physical damage from hurricanes, said Jennifer Moore, a natural resource specialist with the U.S. National Marine Fisheries Service, in a telephone interview.

Corals form reefs that host a variety of marine life, including fish, invertebrates, and turtles, and protect shorelines by acting as a barrier against waves.

Coral reefs also attract divers, boaters and sport fishermen who spend billions of dollars on tourism, said Moore.

Higher temperatures force corals to expel algae living in coral polyps that provide food and color, leaving white calcium skeletons. Coral dies in about a month if the waters do not cool. The Caribbean has been warming for the past 100 years and reached record temperatures in 2005, said Moore.

The U.S. National Oceanic and Atmospheric Administration's Coral Reef Watch said coral bleaching in 2005 centered on the U.S. Virgin Islands, but stretched from the Florida Keys to Tobago and Barbados in the south and Panama and Costa Rica.

Corals have also been bleached by warm waters at the world's largest living reef formation, Australia's Great Barrier Reef. Experts worry that some coral reefs could be wiped out by the end of the century.

Moore said not all of the mechanisms that have caused the Caribbean to warm are known.

But the Center for Biological Diversity, a conservation organization in San Francisco, said heat-trapping gases produced when humans burn fossil fuels and by other sources are warming the waters and harming the coral.

The group said since the 1970s the two corals have declined by more than 97 percent throughout portions of their ranges in the Caribbean.

After the corals are listed under the Endangered Species Act, the government will be required to produce a recovery plan for the species and provide protection to pockets of habitats where the corals have so far avoided declines, Plater's group said.

Source: Reuters