A strong earthquake that struck Indonesia’s Sumatra island two years ago caused one of the biggest coral die-offs ever documented, a study by scientists from two conservation groups found.
The quake itself killed hundreds of people on Nias island off the western coast of Sumatra.
The scientists, who surveyed 35 sites on the coastline, found that the earthquake had raised the island of Simeulue near Nias by up to 4 feet (1.2 meters), exposing most of the coral reefs ringing the island over about 190 miles (300 kilometers) of sea floor, a news statement said.
The scientists were from the U.S.-based Wildlife Conservation Society and the government-backed Australian Research Council Center of Excellence for Coral Reef Studies.
“This is a story of mass mortality on a scale rarely observed,” Stuart Campbell of the Wildlife Conservation Society’s Indonesia marine program said. “In contrast to other threats like coral bleaching, none of the corals uplifted by the earthquake have survived.”
Campbell said, however, that some sites in Simeulue were now recovering.
“At many sites, the worst affected species are beginning to decolonize the shallow reef areas. The reefs appear to be returning to what they looked like before the earthquake, although the process may take many years,” he said.
Andrew Baird of the Australian research center said that the earthquake had provided a one-off chance to study such a phenomenon.
“This is a unique opportunity to document a process that occurs maybe once a century and promises to provide new insights into coral recovery processes that until now we could only explore on fossil reefs,” he said.
The team said it had documented, for the first time in Indonesian waters, extensive damage to reefs caused by the crown-of-thorns starfish, a coral predator that has inflicted huge damage on reefs in Australia and other parts of the world.
“People monitoring Indonesian coral reefs now have another threat to watch out for, and not all reef damage should be immediately attributed to human influences,” said Baird.
Indonesia has some of the richest reef environments in the world, but many have also suffered from human interference. The government has banned the use of chemicals such as cyanide and bombing to catch fish, but such practices still go on in many parts of the huge tropical nation made up of more than 17,000 islands.