Seven popular dive sites in the Andaman Sea will be closed for at least six more months to allow coral damaged by bleaching to recover.
The National Parks Wildlife and Plant Conservation Department ordered the temporary closure of 18 diving sites at seven marine national parks in the Andaman Sea in January last year because of the coral bleaching phenomenon.
Bleaching, or the whitening of coral as it loses its natural pigment, is caused by a rise in sea temperatures, which has been linked to global climate change.
Eleven of the sites were reopened to tourists in November after inspections found the coral had recovered to a satisfactory degree.
However, the officials decided to extend the closure of seven sites at three marine national parks as the coral there remained in poor condition.
The closed sites are Koh Hin Ngam, Hat Sai Khao, eastern Koh Dong, southern Koh Dong and Koh Ta Kieng at Tarutao Marine National Park in Satun province; Koh Chuek at Hat Chao Mai National Park in Trang; and Hin Klang at Nopparat Tara-Mu Koh Phi Phi National Park in Krabi province.
Vithya Hongviengchan, chief of the National Park Office, said the department had tightened regulations at marine national parks to provide better protection of the coral and other marine species in areas affected by bleaching.
"We will cap tourist numbers at each dive site, install rope lines to prevent diving at sensitive spots, and will ask operators of dive shops to strictly follow the rules," he said.
In some areas, such as Koh Hin Ngam, diving would be allowed only during high tide to prevent divers from stepping on coral.
Mr Vithya said marine scientists had found a lot of young coral at certain dive sites, which is a good sign that the coral there is recovering.
The department will evaluate how coral is recovering at the diving sites every six months. If signs of degradation are found, the department can order them to be closed again, while those which remain closed could be opened if there is significant improvement, he said.
Meanwhile, Nipon Pongsuwan, acting director of the Phuket Marine Biological Centre, said the average recovery rate at all sites was less than 5% of the damaged coral.
However, the amount of young coral found suggested that recovery was going forward.
He added that if the coral's growth continues unhindered, it can recover within the next four years.
Mr Nipon said coral bleaching should not occur this year as the sea temperature was still at the normal level of 28 degrees.
"Normal sea temperatures are being seen around the Pacific and Indian oceans region," he said.
"Therefore, the coral should be safe from the bleaching phenomenon this year."