Hong Kong’s Victoria Harbour home to 35 species of coral, researchers find
- High level of coral growth put down to success of government’s harbour area treatment scheme
- Researchers plan to map coral growth and upload results to special website for public education
Sun Coral found near Devil’s Peak in Hong Kong. Photo: HandoutVictoria Harbour in Hong Kong boasts 35 species of coral, an unprecedented underwater survey by City University has found.
Researchers, who released their findings on Wednesday, attributed the high level of biodiversity to the success of the harbour area treatment scheme (HATS) by the government in the early 2010s, which significantly improved water quality.
“Conservation efforts between land and sea are very different because we could easily assess the change in forest size with satellite images … but we had not been able to do so underwater,” project manager Jeffery Chung Tzu-hao said.
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“This project allows us to utilise various techniques to map the coral communities, identify the spots with high biodiversity, and help the government or research institutions advance their environmental management strategies.”
Professor Leo Chan Lai, the survey’s principal investigator, said Hong Kong had a wide variety of habitats, with stony coral species, mostly located in eastern waters, outnumbering those in the Caribbean, and which accounted for 10 per cent of the world’s total.
But coral growth in Victoria Harbour has not been studied before.
The research team scuba-dived in the harbour between 2021 and 2023 and deployed a wide variety of tools to map the inshore underwater habitat and record the condition of coral in the area, as well as their distribution.
They studied 12 sites, including seven natural coastlines and five artificial breakwaters, along two sides of the harbour, and identified essential benthic habitats – those at the bottom of the harbour – in five locations.
They were Cape Collinson Lighthouse in Chai Wan, Green Island off the northwest coast of Kennedy Town and the Hong Kong Museum of Coastal Defence in Central.
The rest were along the northern coast, including Fat Tong Chau in Tseung Kwan O and Devil’s Peak in Yau Tong.
The habitat area in Fat Tong Chau was the biggest at 10.42 hectares (25.7 acres), or more than 14 soccer pitches, followed by Cape Collinson Lighthouse, which covers 3.25 hectares.
The team found 35 black coral, stony coral and octocoral species in the five areas.
“The result showed that the Victoria Harbour has a rich biodiversity, and underscored the potential for the recovery of benthic habitats and the restoration of marine ecosystems in the vicinity,” Chan said.
“We also for the first time found a high density of scallops in Fat Tong Chau … and some iconic marine species such as the double-ended pipefish and festive sea slug.
“They had never been found in the harbour before, and could only survive in very clean water.”
The research team said the biodiversity was down to the success of a series of government interventions to clean up the harbour in the 2010s, including the treatment of sewage and a reduction in the amount of sludge entering the harbour.
Chan said the improvement in water quality was not just a result of the Covid-19 pandemic, which caused a drastic reduction in shipping.
“We have seen corals of different sizes – the larger ones existed for a longer time and are more resistant to pollution, while the smaller ones were created after the water quality has improved – all this could not happen in two to three years,” he explained.
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Professor Kenneth Leung Mei-yee, the director of the State Key Laboratory of Marine Pollution, said the map could also allow the government to further assess the environmental impact of harbour development and identify areas that needed more conservation effort.
The government last year proposed to amend the protection of the harbour ordinance, which will allow small-scale reclamation to be carried out without the need to show an “overriding public need”.
But Leung dismissed concerns that the legal change would threaten the environment.
He stressed that the government would need environmental impact assessments for large-scale projects and would implement measures to minimise any impacts from developments.
The team now plans to carry out a second stage of the project.
They will make a more comprehensive assessment of the underwater habitat, including the distribution of coral species, and expand the study to other parts of the harbour, with the help of remote technologies.
Researchers said their coral map would be uploaded to a special website for public education purposes and shared with the Marine Department so vessel operators can be reminded to avoid dropping anchor in sensitive areas.