BioEd Online

Coral buffeted by the Indian Ocean tsunami in December last year withstood the onslaught, according to an investigation of reefs in the Andaman Sea. The discovery contradicts anecdotal reports suggesting that the region's reefs had been decimated by the disaster.

Last week, Coral Cay Conservation, an international organization based in London, published an assessment of the damage to the coral reefs of the Surin Islands Marine National Park, a group of five jungle-covered, granite islands about 60 kilometres off the western coast of Thailand.

Coral Cay's team of marine scientists, led by researcher James Comley, measured damage to 28 kilometres of reef in February and March. They reported instances of upturned or broken coral, coral covered with sediment and coral displaced by the collapse of a reef.

But while some sites suffered severe damage, Comley's team concludes that overall, only 8% of the coral coverage before the tsunami will ultimately have been lost, even if all of the tsunami-damaged coral dies.

"This exceptionally low statistic was a surprise to the survey team," says Comley. In other areas of Thailand, he says, "the proportion of live coral damaged by the tsunami is many orders higher."

However, the damage to reefs elsewhere may be less severe than feared, Comley says, because the researchers also observed early signs of regrowth in broken and upturned corals. "It would appear that a healthy coral reef system may be capable of regenerating rapidly even in the aftermath of a natural event as momentous as a tsunami," the report says.

Human debris

The relatively slight damage to coral around the Surin Islands is probably due to the geography of the area, the researchers add. Many of the sites surveyed are isolated, surrounded by cliffs and steep forested land rather than the settlements and beaches next to some of the hardest-hit reefs.

"Much of the physical damage caused to these less fortunate coral reef systems was brought about by debris swept onto the reef by the receding tsunami waters, much of which is of human origin," Comley explains.

The study¹, one of the most comprehensive assessments of biological systems since the tsunami, illustrates the buffering capacity of healthy coral reefs. "Perhaps this tragic event will add further fuel to the fire for the conservation of these highly valuable and critically important natural resources," says Comley.