Hong Kong's fragile coral reefs get a boost from 3D printing
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A marine scientist from the University of Hong Kong swimming above a cuttlefish last month protecting its eggs inside an artificial 3D-printed clay seabed, designed to work as an artificial bed for corals, in the waters of Hoi Ha Wan Marine Park in Hong Kong.
PHOTO: AGENCE FRANCE-PRESSE
HONG KONG • In jade waters off Hong Kong's eastern shoreline, scientists are thrilled to spot a cuttlefish protecting its eggs inside an artificial 3D-printed clay seabed helping to restore the city's fragile coral reefs.
Hong Kong's small number of coral reefs are some of its best-kept secrets. Around 84 species of coral are found in its waters, scientists say, more diverse than those found in the Caribbean Sea.
Most can be found in remote inlets. But like all reefs in a rapidly warming world, they are under enormous pressure.
Ms Vriko Yu and her team of fellow marine scientists have begun using 3D-printed tiles that work as an artificial bed for corals to latch on to, with promising results.
"The first time we put down the tiles, there were a few fish around," she said. Now the artificial reef laid down last summer is teeming with wildlife, something Ms Yu described as "very, very exciting".
Hong Kong's government commissioned research into local coral ecosystems after the reefs at Hoi Ha Wan Marine Park were struck by bleaching and mass die-offs.
Corals are colonies of billions of living polyp invertebrates hugely sensitive to temperature changes. When they get too hot, they lose their vibrant colour and die.
Repopulating a dead or damaged reef requires suitable ground for coral larvae to latch on to and build a new home. The printed tiles have so far proven dependable.
"3D printing allows us to customise a tile for any type of environment," said the University of Hong Kong's (HKU) Associate Professor David Baker, who led development of the technology.
Tiles carrying 400 coral fragments have been laid on a 40 sq m section of sea floor in the marine park.
"The corals now on the tiles definitely survive better than the traditional way of transplantation," said Ms Yu, putting the success rate at around 90 per cent.
Some projects around the world have sunk ships or concrete onto the sea floor to encourage coral growth. But while those methods have had some success, they can change the chemistry of the water.
The tiles used in the Hong Kong project are made with terracotta.
"(Terracotta) clay is basically soil," said HKU's Associate Professor Christian Lange, adding that it leaves water chemistry unchanged.
Prof Baker hopes the project can identify species with the genetic resilience to endure future environmental stress.
"We might actually be creating a new potential home for corals as they try to escape climate change from equatorial regions," he said.
AGENCE FRANCE-PRESSE
