( AP )- Even coral reefs thought to be pristine are facing challenges, researchers said Thursday launching the International Year of the Reef. The year of the reef is a "campaign to highlight the importance of coral reef ecosystems and to motivate people to protect them," Conrad Lautenbacher , head of the National Oceanic and Atmospheric Administration, said at a briefing.
Climate warming has become an increasing threat to reefs, added Clive Wilkinson, coordinator of the Global Coral Reef Monitoring Network.
Corals have an upper limit of temperatures they can tolerate, he said.
And added carbon dioxide in the ocean water is creating what Wilkinson called the "soda water" effect, increasing the acidity of the water and making it harder for corals to form their shells.
Mark Patterson of the Virginia Institute of Marine Science, reported from the Caribbean island of Bonaire that even there, some effects are being seen.
Bonaire "has been viewed as being a pristine environment," he said. But researchers there have found "troubling factors" including the spread of blue-green algae, which may be killing coral.
"We're seeing more dead and dying coral than we should be," he said, though there are also positive signs, with a return of sea urchins, which had been killed by disease and many algae-eating fish present.
The last year of the reef was held in 1997 and scientists are launching another one this year in an effort to increase awareness of the ecological, economic, social and cultural value of coral reefs as well as to learn more about threats to coral reefs and possibly learn how to solve these threats.
The expedition to Bonaire, in the Netherlands Antilles, is seeking to survey the reefs there which are popular with divers. Researchers are scuba diving on the reef and also using three remotely controlled underwater vehicles to extend their study into deeper waters where there is little sunlight and the details of the corals are not well known.