For the past year, 14-year-old Jeremy Yang and his peers from The Harbour School have been working on what might be one of Hong Kong’s most unique school projects: building seaweed farms along the city’s coastline.
“My role in the seaweed farming project was to plan and design the entire farm using a combination of a 3D modelling app called Blender and sketching it out on paper. I also helped construct the farm,” the Grade Eight student explained.
“Something challenging about building the farm was tying the lashings,” he said, referring to a method to secure pipes together. “If it was not bound properly, the water would undo the knot, and the farm would be disassembled.”
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From the waters off Lamma Island to Tai Shue Wan bay, students and staff from the international school in Ap Lei Chau have helped to set up 10 seaweed farms across Hong Kong.
“[Seaweed] filters the water, so it improves water quality. It also acts as a habitat for a lot of marine animals ... It produces oxygen and absorbs carbon [dioxide] from the atmosphere as well,” explained Handrich Hernando, the school’s social impact and sustainability programme coordinator.
Because of this programme, The Harbour School was named last month on the Top 10 shortlist for T4 Education’s World’s Best School Prize for Environmental Action.
The award aims to highlight schools that are transforming their students’ lives and making a difference in their communities. The top three finalists for the prize will be announced in September, with the winner – who will receive US$50,000 (HK$391,705) to expand its project – to be revealed in October.
What’s so special about seaweed?
Seaweed cultivation has long been practised in many East and Southeast Asian countries, where the plant has played an important role in cuisine. China’s Fujian and Shandong provinces, for example, have many seaweed farms.
“However, in Hong Kong, seaweed [farming] is not very common in the surrounding ocean,” Hernando noted.
The school’s seaweed farming project was inspired by a documentary titled 2040, which explored innovative solutions to the climate crisis. Dr Jadis Blurton, The Harbour School’s head of school and co-founder, recalled how she was struck by a section in the film about seaweed’s potential to combat climate change.
“I remember sitting there and just saying, ‘Wow, who knew?’ I did not know all that stuff about seaweed. If I hadn’t seen it, I wouldn’t have launched the project,” she said.
Scientists estimate that more than half of the world’s oxygen comes from marine organisms, such as phytoplankton and seaweed.
Researchers are studying how seaweed farms can be used to store carbon dioxide as many look to this plant as a way to reduce the greenhouse gases that are warming our atmosphere.
However, scientists also warn that more research is needed to understand seaweed cultivation’s ecological risks, such as its potential to block the sun’s rays from reaching organisms deeper beneath the water.
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‘A real love for the ocean’
To kick off their seaweed project, The Harbour School reached out to experts who helped develop a comprehensive plan that would involve students in the initiative.
Carlos Rius, who specialises in macroalgae studies, was the school’s marine science specialist and led their research on seaweed cultivation. He worked with the school team to identify the best sites where the seaweed farms would not disturb existing ecosystems or introduce invasive species.
Johnson Stanley, the captain of the school’s sailing boat called the Black Dolphin, explained how they chose where to place the seaweed farm structures, each of which measures about one cubic metre.
“We chose a selection of spots based on where we had seen some [seaweed] species growing and well sheltered from the wind,” Stanley said, “and also where we could put the structures safely without causing either a danger to navigation or ... putting them in danger of being washed away.”
They planted two types of seaweed that grow in Hong Kong’s waters: Ulva, a green seaweed, and Sargassum, a brown seaweed.
Students across all year groups learned about seaweed at the school’s research facility, the Marine Science Centre, while some also ran aquarium experiments. Grade Eight pupils spearheaded the design of the farm structures and deployed them into the sea. Older students researched products that could be made from seaweed, such as bioplastics.
“Ten deployed farms are not going to change the harbour. But ... hopefully, more people are realising the benefits of seaweed,” Blurton said, adding that she was proud of how pupils had taken agency over their contributions to the environment.
“We hope that what students can take away is a real love for the ocean and a feeling that ... they can do something to make a change.”
