Andaman Sea coral reefs hit by bleaching

Marine scientists have been closely watching massive coral bleaching in the Andaman Sea, believed to be the worst case in Thai waters for 20 years.

Coral reefs in the Andaman Sea off Phangnga, Krabi and Phuket, including popular diving sites such as the Similan, Phi Phi and Surin islands, have been damaged by the phenomenon.

The bleaching is likely to extend as far as Satun province, and could get worse if sea temperatures continue to rise, said Niphon Phongsuwan, a marine biologist at the Phuket Marine Biological Center (PMBC).

"The coral bleaching began happening last month. Five percent of the coral reefs affected by the phenomenon have already died. More coral will be damaged if the sea temperature remains high," said Mr Niphon.

"We are waiting for the rain, which can help cool down the sea temperature," he said.

The PMBC has been working closely with dive operators, who help monitor the coral bleaching situation. The phenomenon is also occurring in the Gulf of Thailand, such as in Rayong province, Mr Niphon said.

Scientists believe the main cause of coral bleaching is the warming of the oceans, which forces zooxantaellae, an algae which co-exists with the coral and gives it color, to detach from the corals' shell.

Strong sunlight can also kill the coral. The bleached coral reefs will take a long time to recover, according to Mr Niphon.

Coral reefs in shallow waters at depths up to 10m will take three to four years to recover. Coral in deeper seas will take more time to recuperate.

Somkiat Khokiattiwong, head of the PMBC's oceanography and environment unit, said high temperatures in the Andaman Sea and the central part of the Bay of Bengal were the likely cause of the massive coral bleaching.

The temperature in the Andaman Sea stood at 31-32C for a long period this year, making the sea warmer than the previous two years.

He believes the warmer-than-usual sea temperature is a consequence of the late onset of the monsoon over the Bay of Bengal and Andaman Sea. Monsoons usually arrive around mid-April. But this year, the rainfall came a little bit later than usual.

Burma and Malaysia could also face the coral bleaching problem in their waters, Mr Somkiat said.

The Andaman Sea is one of the country's most popular diving sites with around 80 sq km of coral reefs. It attracts millions of visitors and divers each year. Coral reefs in the Andaman Sea previously suffered severe bleaching in 1991 and 2003.


Source:
Bangkok Post, "Andaman Sea coral reefs hit by bleaching", accessed May 10, 2010