Chemical Changes May Stunt Coral Development, IHT, 10/25/06
Source: International Herald Tribune
CHARLOTTE AMALIE, U.S. VIRGIN ISLANDS - Rapid increases in ocean acidity may keep coral from growing outside its traditional habitat in the tropics, which is becoming too hot for the fragile undersea life, researchers said Wednesday.
Carbon dioxide released from burning fossil fuels will make the oceans dramatically more acidic in the next 50 years, which could hinder the development of new coral colonies, Mark Eakin, director of the National Oceanic and Atmospheric Administration's Coral Reef Watch, said at an international coral meeting in St. Thomas.
He said that due to rising ocean temperatures, the fragile undersea life could grow in newly warm waters outside the tropics. But acids there would break down the calcium carbonate it needs to develop skeletons, and which aquatic animals use to make shells.
"This doesn't mean (existing) corals are all going to die," Eakin told nearly 200 researchers from the Caribbean, Florida and U.S. Pacific islands who gathered for NOAA's U.S. Coral Reef Task Force biannual meeting. "But it does affect their reef-building ability."
The coral can grow more slowly, become more brittle or divert energy from injury recovery and reproduction, he said. That threatens reefs, because the coral may be unable to build them as fast as they are eroded.
Coral within the tropics has already been devastated by warmer waters and disease.
Last summer, nearly half of the coral in parts of the U.S. Virgin Islands died from disease outbreaks after months of hot seas. Similar conditions killed 5 percent of coral in Australia's Great Barrier Reef in 1998 and in 2002.
Researchers have predicted that up to 60 percent of the world's coral could die by 2030 if ocean temperatures and pollution levels continue to rise. Carbon dioxide and other greenhouse gasses contribute to rising sea temperatures, Eakin said.
The reefs, the ocean's largest concentration of plant and animal life, fuel a multibillion dollar (euro) tourism industry globally.
"This is a growing problem and abnormally one that will be very important in the next few decades," Eakin said. "These are levels we have not seen. These are levels we're not sure what kind of impact they will have."
Researchers estimated that between 1800 and 1994 the world's oceans absorbed 118 billion metric tons of carbon, reducing the natural alkalinity of seawater. Oceans are normally slightly more alkaline than acidic.
Northern seas are naturally more acidic than equatorial waters because cold water can absorb more carbon dioxide than warm water, Eakin said.