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About half of all coral reefs on the planet have died in the past 70 years, forcing governments and scientists around the world to urgently address this issue, said Rob Toonen, a professor in the University of Hawaii Institute of Marine Biology.

One of those large-scale experimental responses — a part-natural, part-artificial reef with a base made of concrete and steel — will be built in Hawaii and cost about $25 million.

Correction: An earlier version of the story incorrectly called it an iron reef.

The first deployment of this five-year project will include construction of a 50-meter-long prototype reef off the Marine Corps Base on the Mokapu Peninsula on Oahu. Construction is expected to begin once a final design is approved. That part of the project is expected to be completed by June 2024. 

The part-natural, part-artificial reef is expected to decrease wave energy in its area, host an engineered ecosystem and support adaptive biological experiments to potentially breed more coral and coral that can survive in a warmer ocean. 

For the biology part of this project, researchers are testing what works best in such environments and then they will add those biological parts to the artificial structure for the prototype. These alternatives include the “settlement modules, live corals, settlement cues for larvae, the fish houses,” Toonen said. 

The researchers will then observe the prototype in the field and study it to see what the effects are for several years.

In parallel, the state is preparing to fund several other similar efforts around Oahu, said Ben Jones, the principal investigator of the project and the director of ocean science and technology at the Applied Research Laboratory at University of Hawaii. 

“If this project works anywhere close to what we hope for it,” Toonen said, “that will allow us to then install these in other locations around the state of Hawaii.”

People can build structures, Toonen said, but this project explores if people can build something better by working with nature.

The $25 million grant for this project was provided by the U.S. Department of Defense, under its Defense Advanced Research Projects Agency, with the intended aim of protecting infrastructure and decreasing coastal erosion.

With this funding, different organizations in the state will have opportunities to collaborate on a single project rather than chasing separate grants and working without a holistic end in mind. 

There are five laboratories at the University of Hawaii participating, plus Makai Ocean Engineering and two academic partners, the University of California, San Diego and Florida Atlantic University.

“We have seen (negative effects of losing coral reefs) for a long time,” Jones said. “And we are now looking for ways to mitigate these challenges.”