A team of scientists have developed a 3D-printed structure for coral to grow upon, an achievement that could help embattled coral reefs recover from the many threats they face around the world, according to a University of Delaware press release.
The 3D-printed model acts as a support system for baby coral to float onto and grow upon. Over time, the biodegradable material decays, leaving behind only coral, and setting the stage for a full-blown reef to develop.
As the coral grows, the structure also provides protection, spawning grounds, and food to countless species that depend on reefs for their survival.
“Offering 3D-printed habitats is a way to provide reef organisms a structural starter kit that can become part of the landscape as fish and coral build their homes around the artificial coral,” said Danielle Dixson, an associate professor at UD and the lead scientist developing the structure. “And since the materials we selected are biodegradable, the artificial coral would naturally degrade over time as the live coral overgrows it.”
The researchers embarked on the project because of the increasingly dire state of coral around the world. Climate change is causing the ocean to warm up far faster than land environments. As a result, marine heat waves are becoming more common. Coral is highly sensitive to temperature fluctuations and large sections of reefs are dying during these heat waves through a phenomenon called “coral bleaching.”
The Great Barrier Reef, for example, has lost large swaths of coral to bleaching.
Coral reefs are further threatened by ocean acidification, when the water’s pH level becomes too acidic in response to absorbed carbon dioxide.
Other threats facing coral include industrial pollution, overfishing, extractive industries, and plastic pollution.
The UD researchers were thinking about plastic pollution when they were developing the 3D structure — the last thing they wanted to do was contribute to the problem by throwing a hunk of plastic into the water.
They landed on two materials that could withstand the ocean’s conditions and would biodegrade over time — corn starch and corn starch mixed with stainless steel powder.
They then 3D-printed a coral skeleton by consulting images of reefs from 50 different angles and installed in waters around Fiji, where coral has been especially impacted by bleaching events.
Via University of Delaware: During field studies in the tropical waters off the island of Fiji, Emily Ruhl, then a UD graduate student, studied the habitat preferences of humbug damselfish by placing the fish in enclosures containing 3D-printed coral.
The end result was resilient, harmless to marine species, and capable of supporting the organic growth of a reef, according to the scientists.
“I thought the natural skeleton would elicit more docile (that is, accepting) behavior compared to 3D-printed objects,” said Emily Ruhl, the lead assistant on the project. “But then we realized the small reef fish didn't care if the habitat was artificial or calcium carbonate, they just wanted protection.”
The 3D model could eventually be used in various marine environments, acting as a crucial stabilizing force for reefs nearing collapse.
Similar efforts to rehabilitate reefs have been tried around the world. Oil rigs have been converted into thriving marine ecosystems, old subway cars have been dumped into the ocean to foster marine life, and teams of conservationists have manually planted grids of coral in areas affected by climate change.
The 3D-printed model could become a go-to intervention for coastal countries that depend on reefs for food, tourism, protection, and more.