Corals are disappearing all over the globe, here’s how Hong Kong’s coral coverage is being restored.
By Lunaretta Linaura
Thomas Fong, oceans conservation officer at the World Wildlife Fund (WWF) Hong Kong, dives every month to check on the health of corals in Hoi Ha Wan, a marine park located in the countryside of Sai Kung.
Fong compares corals seen underwater to a colour chart, which is used to determine the health of corals.
“The more intense the colour, the healthier [the coral] is,” Fong says.
Coral gets its colour from algae that thrive inside the structure, which is also the coral’s primary food source.
Without the algae, coral turns white and is more prone to disease and death. The process is known as coral bleaching and can be caused by reasons including rising water temperatures.
Coral coverage – a measure of how much of the reef surface is covered in live corals – in Tolo Harbour and Channel dropped from about 80 to under ten percent between 1980 and 1985, due to the Sha Tin and Tai Po New Town development that came with residential and industrial sewage disposal into the water, according to the WWF.
In an attempt to bring back this abundance, the WWF started a coral restoration programme called “Reviving Our Corals” in 2023 in collaboration with the Chinese University of Hong Kong, to foster increased resilience of marine communities reliant on corals.
Fong explains that Hong Kong corals have a slow growth rate of one to two centimetres per year, combined with more frequent bleaching events, human intervention is key to coral recovery.
“We know that corals are not able to recover by themselves, so we need to do coral plantation as active restoration work. We hope that the next generation of corals will be able to sustain themselves,” Fong says.
Restoration works involve bringing living fragments that have broken off corals into a coral nursery, and transplanting them into the Tolo Harbour when they have grown bigger in size. Some 90 percent of the corals transplanted there have survived, according to Fong.
Coral fragments collected are planted onto a stable substrate and grown in the coral nursery.
The WWF also holds workshops for local divers to learn how to transplant corals and conduct emergency rescue when they find a coral fragment underwater.
“We want the public to have a taste of coral restoration work and support us because coral restoration is not easily done by only a few people. We want divers to have knowledge on how to do coral restoration work in hopes they can join us and raise public awareness,” Fong says.
The last restoration workshop in 2024 received 200 sign-ups from divers within two days.
The WWF also hosts around 140 educational tours and activities for schools and other groups each year.
“For students, we want them to have a closer bond with the ocean. Here, we give them a chance for exploration by, for example, doing experiments with seawater,” Fong says.
Covering less than 0.1% of the ocean, corals are home to at least a quarter of all marine species and benefit an estimated 1 billion people, according to a 2020 report by the Global Coral Reef Monitoring Network.
Corals also support tourism, fisheries, coastal protection, medicine, and welfare of coastal communities.
The services coral reefs provide are valued at US$2.7 trillion, according to the same 2020 report.
Due to factors such as warming waters and increased rainfall, coral bleaching has become a worldwide phenomenon.
In June 2024, the United Nations Environment Programme (UNEP) announced that a new global mass coral bleaching event had started. The last mass bleaching from 2014 to 2017 left about nine percent of the world’s corals dead.
Hong Kong’s corals are no exception to this danger. According to the Hong Kong Observatory, local waters have experienced a significant five percent annual warming since 1975.
Annual average sea surface temperature recorded at North Point between 1975 and 2024 (Courtesy of Hong Kong Observatory)
But Fong adds Hong Kong coral might have a chance to survive: “Unlike in the tropics, Hong Kong’s waters do not stay hot all the time. When the water cools, coral bleaching is reversed.”
Archireef is a Hong Kong start-up involved in coral restoration, best known for its 3D-printed tiles made out of terracotta clay.
David Michael Baker, Archireef’s co-founder, explains that the tiles is the first step to rehabilitate the seabed with living coral fragments.
“As the corals continue to expand and grow, they contribute to connecting Hong Kong’s patchy coral communities to attract more wildlife and form richer, more resilient ecosystems,” Baker says.
According to Archireef, these planted corals have started to reproduce, a sign that the restoration is effective. The company has extended its work deployment of reef tiles to the UAE, and is seeking further expansion to Southeast Asia.
Hong Kong’s Agricultural, Fisheries, and Conservation Department (AFCD) points out that Hong Kong is home to a higher coral diversity than the Caribbean Sea. Local coral-rich destinations include Tung Ping Chau Marine Park, Hoi Ha Wan Marine Park, Bluff Island, Sharp Island and Crescent Island.
“Some of the coral communities we have are quite impressive. On a good day, there are even some patches of reef here that look even better than places I’ve seen in Indonesia or the Great Barrier Reef,” Baker says.
Baker distinguishes Hong Kong as a “hope spot”, from which the understanding and appreciation of local corals can inform a future where more resilient coral communities grow.
“Not only are there many species of coral [in Hong Kong], but in some places they’re doing quite well,” says Baker.
“We shouldn’t be thinking about amusement parks, new shopping malls, we should be thinking about what’s all around us, including these country parks, and marine parks, there’s a tremendous amount of valuable things out there that I don’t think we’re leveraging in the right way,” he adds.
*Theme picture (photo courtesy of Jason Lau/WWF-Hong Kong)
