Wednesday, April 22, 2009

Damaged Barrier Reef coral makes 'spectacular' recovery

Guardian (UK): Sections of coral reef in Australia's Great Barrier Reef have made a "spectacular" recovery from a devastating bleaching event three years ago, marine scientists say. In 2006, high sea temperatures caused severe coral bleaching in the Keppell Islands, in the southern part of the reef — the largest coral reef system in the world. The damaged reefs were then covered by a single species of seaweed which threatened to suffocate the coral and cause further loss.

A "lucky combination" of rare circumstances has meant the reef has been able to make a recovery. Abundant corals have reestablished themselves in a single year, say the researchers from the University of Queensland's Centre for Marine Studies and the ARC Centre of Excellence for Coral Reef Studies (CoECRS).

"Three factors were critical," said Dr Guillermo Diaz-Pulido. "The first was exceptionally high regrowth of fragments of surviving coral tissue. The second was an unusual seasonal dieback in the seaweeds, and the third was the presence of a highly competitive coral species, which was able to outgrow the seaweed."

Coral bleaching occurs in higher sea temperatures when the coral lose the symbiotic algae they need to survive. The reefs then lose their colour and become more susceptible to death from starvation or disease. The findings are important as it is extremely rare to see reports of reefs that bounce back from mass coral bleaching or other human impacts in less than a decade or two, the scientists said. The study is published in the online journal PLoS one….

Divers survey the coral at Australia's Great Barrier Reef, shot by Steveprutz, Wikimedia Commons, under the Creative Commons Attribution 3.0 Unported License