Encouraging signs for delicate coral gardens

PUBLISHED : Sunday, 17 December, 2006, 12:00am
UPDATED : Sunday, 17 December, 2006, 12:00am

Hong Kong's coral gardens are in better shape than they were a year ago, flourishing despite threats from global warming, trawling and tourism.

The Coral Watch index gave 24 coral sites a rating of 4.24, up from last year's 3.85, said Alan Chan Lai-koon, senior marine conservation officer of the Agriculture, Fisheries and Conservation Department.

He said the index - which ranges from 1 to 6 - measures the colour intensity of the coral, which in turn reflects the amount of its main energy provider, the symbiotic algae zooxanthellae.

The higher the level on the index, the healthier the coral, Mr Chan said.

'The better situation can be attributed to the use of coral marker buoys, which help remind boats not to anchor in the waters of healthy coral reefs,' Mr Chan said.

The annual survey - which has been jointly carried out by the department and the Reef Check Foundation since 2000 - attracted more than 330 volunteer divers who, from July to September, checked a total of 33 coral sites mainly in eastern Hong Kong waters extending from Ping Chau in the north to the Ninepin group in the south.

Some 23 sites, including those in Tung Ping Chau, Kat O and Lai Chi Wo, recorded high coral coverage levels of more than 50 per cent. The coral garden at Hoi Ha Wan Marine Park was the highest with 73.1 per cent coverage.

However, abandoned nets and other marine rubbish were found at seven coral sites such as Wong Ye Kwok of Tung Ping Chau and Sharp Island East, which Mr Chan classed as 'tourism hot spots'. 'These delicate marine animals can be destroyed by abandoned nets dumped by fishing boats. We will be educating the public about how to protect coral reefs,' he said.

Reef Check Foundation co-ordinator Terence Fong Ching-wai said there was increasing concern, with the growth of ecotourism, about the damage caused by leisure divers.

'More people are enjoying diving or snorkelling through ecotourism, but we are not sure if they are touching or collecting the coral. This type of damage to the delicate and slow-growing organism has become a new concern for us,' Mr Fong said.

Global warming also poses a threat to Hong Kong's coral gardens. The survey found coral bleaching was observed at five sites and it is believed this summer's elevated water temperatures in these areas caused the problem. Mr Chan said, however, the impact was minor, with less than 5 per cent of the coral affected. Coral dies within a short time of being exposed to bleaching. Hong Kong is one of the world's northernmost sites where coral is known to flourish. Corals in Hong Kong do not have a true reef structure, normally forming scattered fringing coral communities.