Ao Phrao is the most important coral site on the western side of Koh Samet," said Thon Thamrong-nawasawat, a marine science expert at Kasetsart University's faculty of fisheries.
Since most local coral reef is hump coral which grows very slowly at 1-4 centimetres a year, "We don't know how long it will take to recover from the impacts of this spill and how much damage has been caused there," he added.
The oil slick formed about 20 kilometres off the coast of the eastern province of Rayong, drifting for 35 kilometres towards Koh Samet Island, a tourist resort near Bangkok, famous for its white beaches.
For Rayong Province Governor Wichit Chartpaisit, PTT Global Chemical Pcl, the company that operates the pipeline, has to bear all responsibility for the incident and environmental disaster.