It is believed that increased ocean acidification is the main culprit.
Glenn De'ath and colleagues at the Australian Institute of Marine Science in Townsville, Queensland, examined Porites coral samples stretching as far back as 1572. Because Porites lay down annual layers—like tree rings—changing environmental conditions are etched into their skeletons.
The team, which published the findings in the journal Science, looked at a total of 328 colonies spanning the 1,600 mile long reef which is off the north east coast of Australia. They found that growth slowed by roughly 13 percent since 1990.
Hard corals "are central to the formation and function of ecosystems and food webs, and precipitous changes in the biodiversity and productivity of the world's oceans may be imminent."
The Great Barrier Reef is the largest coral reef system in the world—and the biggest sign of life on Earth, visible from space. It is a collection of 2,900 reefs along 2,100 km (1,300 miles) of Australia's northeast coast in a marine park the size of Germany.
Full articles on the wildsingapore news blog.
- Declining Coral Calcification on the Great Barrier Reef
Glenn De'ath, Janice M. Lough, Katharina E. Fabricius
Science website 2 Jan 09