Global warming and pollution are decimating coral reefs around the world, with only 25 percent in good health in the Caribbean Sea, US experts warned Tuesday.

In other areas of the world such as the Pacific basin, nearly 70 percent of the coral reefs are either thriving or in good condition, the National Oceanic and Atmospheric Administration (NOAA) said in a report.

NOAA told the 11th International Coral Reef Symposium in Fort Lauderdale, Florida, that nearly half of coral reef ecosystems in the United States are in poor or barely passable condition.

"This is absolutely a call to action," said NOAA Coral Program director Kacky Andrews.

To reverse the deterioration and lessen the threat to coral reefs, she strongly suggested curbing emissions of carbon dioxide and other greenhouse gases and the use of fertilizer, prevent damage from anchors and stop the sale of coral for jewelry.

"In the Caribbean, parts of Jamaica, Dominican Republic and Mexico that have been strongly impacted by hurricanes in the past few years, large communities of coral have been lost," Diego Lirman, a University of Miami Rosentiel School of Marine and Atmospheric Science expert, told AFP.

He said the Caribbean region, which sustains only 60 or 70 species of coral compared to more than 500 in the Pacific, "has lost a large part of its most ancient corals, which ... can be more than 500 years old and make up the reef's basic structure."

While reports indicate a worldwide reduction in coral reef covering, in the Caribbean the problem is compounded by the reefs' increasingly slow rate of recovery, Lirman said.

"In some places protected zones have been set aside, but the fact is many countries lack the means to monitor them -- there are no patrols in the area and no real measure of control," the expert said.

Nonetheless, he said the University of Miami has a coral reef recovery program.

"We extract some corals, help them to grow and get stronger and return them to their communities in better condition so they can reproduce, or we take them to places where (coral reefs) have died off."

Development and overfishing also pose a threat to coral reefs, said Chantal Collier, with the Florida Department of Environmental Protection.

"In Florida, which has the third longest reef system in the world, coastal population has grown by 64 percent in the past two decades, putting pressure on the reefs from development," Collier said.

"Fishing is an activity of major concern in Florida, which is known as the fishing capital of the world," he added, noting that fish keep coral reefs healthy by cleaning them of algae that can overgrow and choke off nutrition.

The five-day Coral Reef Symposium ending Friday brings together some 2,500 scientists, conservationists and government officials from 114 countries. It is held every four years.