THE CORAL reefs surrounding Koh Samet's Ao Phrao, a bay that was badly affected by an oil spill in July last year, are showing signs of recovery, with levels of coral bleaching declining, according to the results of a study released yesterday.
Meanwhile, a team of marine scientists from Kasetsart University said the efforts to rehabilitate Ao Phrao would take three to seven years due to the chemical substances remaining in sediment on the seabed in the affected areas.
However, they found that marine animals have returned to the area, with no traces of toxicity in fish samples collected.
Marine Science Department head Assist Prof Thon Thamrongnawaswat, who led a team of scientists studying the area, said that in the six months following the oil spill, the amount of petroleum hydrocarbons in the sand of Ao Phrao Beach had steadily decreased. The coral reefs have generally recovered from acute bleaching stress and begun to return to normal in some areas, the results of ongoing monitoring of Ao Phrao’s ecosystem and surrounding natural environment show.
The oil spill occurred while crude oil was being transferred from a PTT Global Chemical offshore pipeline to a tanker at 6.30am on July 27. A gust of wind apparently destabilised the tanker receiving the oil, which caused the pipe to disconnect from the vessel, according to an investigation team led by Khunying Thongtip Ratanarat.
However, Thon said ongoing close monitoring was necessary as bleaching may recur in the near future as a result of global warming. Coral bleaching could become a chronic issue, he said.
Meanwhile, the fish population is within its normal range, and crab and other marine populations have begun to increase.
“Although the environmental conditions have not returned to 100-per-cent normal, we have to continuously monitor the impact on sediments. But their condition is not as critical as many parties initially feared,” Thon said.
His team also expressed concern that some ecological-rehabilitation activities being conducted were unnecessary. He urged relevant agencies to wait at least one year after the oil spill to conduct such activities, and to follow clear guidelines, in order to maximise the efficiency of the rehabilitation efforts.
“We are worried that any rehabilitation activities under the sea at Ao Phrao Beach would cause crude-oil sediment located on the seabed to spread, and this would make future recovery efforts harder,” he added.
Recently, the team found that some tourism businesses had taken tourists to see marine life under the water at Ao Phrao. These activities had harmed the recovery of coral hit by bleaching, he said.
Thon said his team expected that the recovery efforts at Ao Phrao would take three to seven years.