Project aims to kick-start Waikiki coral reefs

There was a time, about a century ago, when visitors marveled at Waikiki’s coral reefs and abundance of marine life.

Today, corals and fish are pretty sparse in the waters off the world-famous beach. The former marshland has undergone much change, and for decades its waters have endured runoff and flagging water quality plus overfishing.

But a new effort funded by a $8.9 million grant from the National Oceanic and Atmospheric Administration is aiming to turn that situation around with the construction of two permanent coral nurseries offshore that will grow into healthy coral reefs.

The REEFrame project, as it is being called, is a partnership of the University of Hawaii at Manoa, Conservation International, the state Division of Aquatic Resources, ocean technology firm Natrx, ocean engineering firm Oceanit and ClimbHI, a workforce development nonprofit.

“Waikiki is not a reef in particularly good health,” said the REEFrame science lead Mark Hixon from UH Manoa’s School of Life Sciences. “It is among the most degraded coral reefs in Hawaii, with only occasional patches of coral.”

The initiative, announced Friday, is one of nearly 150 projects across 30 coastal and Great Lakes states and territories that were tabbed by the Biden administration to receive a total of $562 million from the Bipartisan Infrastructure Law and Inflation Reduction Act as part of the administration’s Climate- Ready Coasts initiative.

Of the total, some $26 million was recommended for Hawaii, with the REEFrame project drawing the largest award here, in part because Hixon already demonstrated that offshore coral nurseries can work. Since 2016, he has created miniature versions of the REEFrame project off Waikiki and Hanauma Bay. The data from those experiments helped score the project’s substantial funding.

“I’m excited,” said project coordinator Matt Ramsey of Conservation International. “Corals both globally and locally are threatened and facing a lot of impacts. We need to be trying out new approaches and doing what we can to give corals a helping hand.”

For REEFrame, the plan is to build two permanent coral nurseries — each about 100-by-100 feet and about 6 feet tall — on a bare rock seafloor in about 55 feet of water about three-quarters of a mile off Waikiki Beach.

Construction is expected to begin in 2025 after environmental studies and specific plans are completed and a raft of permits are obtained.

The permanent frames of the nurseries/future reefs would be made of stacked 3D-printed concrete modules in organic shapes with many holes and overhangs where fish, coral larvae and other sea life can take up residence. In addition, scientists will populate the structure with newly broken corals, which would die otherwise, and with nursery- raised sea urchins to help prevent seaweed from taking over the new reefs.

If everything goes as planned, the structures will gradually be colonized by naturally settling coral larvae and attract parrotfish and other seaweed eaters that help keep reef surfaces clean and thriving.

Along the way, project partners plan to reach out to school students, visitors and anyone else interested in helping out and learning about the importance of Hawaii’s coral reefs.

The project is scheduled to run from mid-2023 to mid-2026, but don’t expect to see fully grown reefs for awhile.

“Corals grow very slowly — a half an inch a year,” Hixon said. “I would expect in 10 years it would look like a reef.”

Those wondering if the new coral reefs will affect Waikiki’s surf spots, the answer is no, according to Hixon.

“All the major players (in the project) are surfers. The last thing we want to do is interfere with surf spots,” he said.

Hixon hopes the project will be a model for rebuilding reefs along other degraded shores.

“Frankly, Hawaii has done a terrible job of caring for its reefs,” he said. “This is like a last-ditch effort to save our reefs.”

A 2020 aerial survey of Hawaii’s coral reefs found vast areas of decline and degradation across the state, with Oahu’s reefs in the worst shape. Only 12% of Oahu’s ocean substrate is covered by live coral, the lowest percentage of any island, a survey by Arizona State University researchers found.

Hawaii’s reefs have declined over the years for a variety of reasons, according to scientists. Coastal development has sent silt and mud into the water, smothering corals, while nutrients from fertilizer and cesspools have spurred growth of seaweed, which smothers and strangles reefs.

What’s more, too many of the herbivores that eat seaweed have been taken from the reef.

Now climate change is causing increasing ocean acidification and warmer waters that trigger lethal bleaching of corals. Hawaii’s corals experienced serious bleaching in 2015 and 2019, and scientists predict that bleaching events will be a yearly occurrence by the year 2040.

“We don’t have a lot of time to get ready,” Hixon said.

Meanwhile, the REEFrame project isn’t the only UH- Manoa project trying to create a hybrid coral reef in Hawaii. Scientists with the university’s School of Ocean and Earth Science and Technology, and Applied Research Laboratory are working to create a part-artificial, part- natural reef structure for Oahu’s windward coast in a project funded by the U.S. Department of Defense.

There is a difference between the two: The DOD project primarily aims at protecting the shore from storms and rising seas, while the NOAA effort focuses on reviving the nearshore ecosystem.

If they are both successful, they may ultimately offer the same functions.