When Hong Kong’s strongest super-typhoon on record hit Hoi Ha Wan bay, in 2018, up to 80% of the local corals were destroyed – leaving little but a sandy bottom in its wake. Such stories are becoming all-too-familiar, highlighted by the Great Barrier Reef suffering its third serious bleaching event in five years.

While reducing greenhouse gas emissions is easily the most pressing action in the fight against coral degradation, rising ocean temperatures are not the only impact. Irresponsible tourism, destructive fishing practices, pollution, and natural disasters all also play a part, and there are many smaller battles being waged on front lines across the globe - and beneath the sea.

As reported in The Guardian, a team from the University of Hong Kong are currently trialling the use of 3D-printing to restore Hoi Ha Wan bay’s storm-damaged reefs. The team is using this technology to create hard, hexagonal terracotta tiles to act as a substrate for new coral growth.

Terracota Tiles
image source: The Guardian

Terracotta is a similar material to calcium carbonate, and according to The Guardian, the team have used biomimicry to replicate the intricate patterns found on brain coral – providing an suitable home for young coral fragments. Standing above the sand on small legs, these tiles protect the coral from the rough, shifting sand beneath and deliver better access to sun and nutrients. And even better, by using terracotta instead of concrete, these tiles are far more eco-friendly than many other artificial reefs. Not only does the manufacturing of terracotta produce less CO2 emissions, but it is also less caustic and should eventually erode, leaving nothing but natural coral reef in its place.

Overall, David Baker, director of the Swire Institute of Marine Science (Swims), says he hopes to plant multiple ‘patch reefs’ that will go on to become “significant biodiversity hotspots, enjoyable dive sites, and contribute to increasing corals within Hong Kong”.

Terracota Reef
Image source: The Guardian

This innovative approach to coral restoration covers just 40 sqm but hopes to be rolled out elsewhere if it proves successful. The article suggests 3D printing is also being used to restore reefs in France, the Caribbean, and the Maldives – home to the world’s largest 3D-printed reef.