Marine scientists at the University of Hong Kong have developed a new method of saving coral reefs off the coast of the city. Specially designed terracotta tiles are being 3D printed to create artificial reefs in Hoi Ha Wan Marine Park.
The 2.6 square kilometre marine park is a local biodiversity hotspot and is home to more than 60 species of coral. However, a super-typhoon destroyed 80 per cent of the corals in the area in 2018 and few species survived. Now, if left alone, it would take decades for the species to regenerate naturally.
Coral reefs are badly affected by climate change. They support 25 per cent of all marine life, providing food, shelter and a place for other organisms to raise their young. Around 500 million people around the world also rely on them for their livelihood. For communities close to coral reefs, they are a source of food, provide protection from the elements and income through tourism.
Warming oceans lead to mass bleaching events and frequent storms, like the one in Hong Kong, which cause devastating damage. According to one recent study, researchers estimate 75 per cent of the planet’s coral reefs are threatened by “habitat loss, climate change and other human-caused disturbances”.
Tiling the seafloor
Developed by the university’s Robotic Fabrication Lab, these “reef tiles” help corals to survive by creating a surface for them to attach to. Coral fragments cannot easily attach to the seafloor because it moves - and abrasive grains of sand can damage their delicate tissue too.
The reef tiles were 3D printed using clay and then fired in a kiln at 1125 degrees Celsius to harden into terracotta. Their intricate designs were inspired by the natural patterns of corals and the team claim the material is more eco-friendly than metal or concrete alternatives. Terracotta will naturally erode over time meaning that in a few decades, all that will be left are the new corals, say the scientists involved with the project.
Covering 40 metres square, 128 of the tiles were seeded with coral fragments and installed at three sites in July this year. When attached to the tiles, the fragments are lifted off the seafloor to prevent the sand from damaging them and to bring them closer to sources of light and nutrients.
The variety of corals seeded have different growth forms, which is intended to create a biodiverse environment to allow other marine species to flourish. Researchers hope that this new method will be a vital contribution to global efforts to save coral reefs around the world.