Why Waikīkī?
As the the most collapsed and degraded coral reef in Hawai‘i, it needs extreme restoration including supportive structures for new coral growth and shelter for fish. According to early visitor accounts, Waikīkī was once home to healthy, rich, productive coral reefs and plentiful fish catches, therefore we know there is high restoration potential.
What is the REEFrame project?
REEFrame is a $9 million, three-year (2023-2026) coral restoration project on O‘ahu, Hawai‘i, funded by the National Oceanic and Atmospheric Administration’s (NOAA) Office of Habitat Conservation.
What is the purpose?
REEFrame is a first step towards restoring healthy coral reefs and fish habitats on O‘ahu by building two permanent coral nurseries off Waikīkī Beach. Many things have compromised these fragile ocean resources. Sediment from poor land management has smothered them, and seaweed has overtaken them due to excess fertilizers and leeching sewage. Ocean warming also plays a role, causing lethal coral bleaching. In fact, scientists expect warmer water to bleach coral every year by 2040.
Who are the key players?
NOAA awarded the grant to Conservation International Hawai‘i to manage the work of the University of Hawai‘i at Mānoa and Natrx, an ocean technology firm. Oceanit, a marine engineering company, and the Hawai‘i Division of Aquatic Resources are supporting the effort. ClimbHI, a workforce development nonprofit, will facilitate public engagement, outreach, and educational efforts.
How will REEFrame help restore and protect coral?
Natrx is building two permanent coral nurseries, each about 100 feet by 100 feet and about 6 feet tall, on a bare rock seafloor in deep water approximately ¾ mile off Waikīkī Beach. They will be made of stacked 3D-printed concrete modules in organic shapes with holes and overhangs for fish and other sea life. The nurseries will attract fish and corals and naturally growing coral will eventually colonize the nurseries.
When do you expect natural coral to grow in the nurseries?
Once the structures are installed, they will serve as temporary nurseries for “corals of opportunity,” (detached living coral colonies found on nearby reefs that were dislodged by storms or other disturbances). This gives the coral and fish a chance to thrive. A preliminary study using concrete structures in the same Waikīkī habitat showed that corals naturally appear on the cement structures about one year after installation.
When will the project begin?
The project will begin as early as 2025 after the partners have finalized plans, environmental studies, and permits. In 2024, the partners will meet with regulatory agencies and stakeholders, engage the community, select a site to fabricate the structures, transport the 3D printer to Hawai‘i, and choose a site for the coral nursery.
How will the reef be constructed?
Natrx will build the REEFrame modules with an advanced manufacturing technology called DryForming, 3D printing that uses sand and limestone cement to recreate the texture and structure of natural reefs.
Why is your plan best for this?
Our approach rebuilds lost habitats using our knowledge of how reef systems work. Natrx’s technology is the only one that can create specific habitat features and mimic Hawai‘i’s natural reefs at scale. The modules will create a refuge and habitat for reef fish who will inhabit them and keep the corals of opportunity clean and healthy. Previous research by the University of Hawai‘i and REEFrame team member Mark Hixon, Ph. D., proved this technique’s effectiveness.
How is this different from artificial reefs?
The REEFrame structures are designed to serve primarily as coral nurseries, providing attachment sites for corals of opportunity for reef restoration projects. Secondarily, these permanent structures will also provide shelters of a variety of sizes, thereby functioning as artificial reefs as they are naturally colonized by corals, fish, and other sea life.
Eventually, they will become de facto natural reefs.
Are the REEFrame structures safe for plants and animals?
The structures are completely safe for plants and animals including the green sea turtles and monk seals. Tests conducted by the University of Hawai‘i in 2016 showed that corals attached, grew, and thrived on the concrete modules. In addition, partners will undertake a lengthy permitting process at city, state, and federal levels to ensure they complete the project safely and effectively.
Will the coral structures release any pollutants or hazardous materials into the water?
No. The coral nurseries are green-gray infrastructure, made of natural and engineered features designed to increase the potential for coral restoration while strengthening the coastal habitat for the community. They will be made of local, nontoxic cement materials including Hawaiian sand. They don’t contain contaminants and won’t release pollutants or hazardous materials into the water.
How will you know if REEFrame is successful?
Any efforts to restore O‘ahu’s coral population will help rebuild a habitat for fish and ocean life. In addition, REEFrame partners will conduct quarterly evaluations to assess the project’s success. The group expects at least an 80% survival rate for each coral species 90 days after the coral nursery is installed.
What is the plan to clean up if the reef doesn’t succeed?
Even if corals don’t thrive on the REEFrame structures, they will succeed as permanent habitats for fish. Globally, much of our living coral could die if accelerating ocean warming causes frequent bleaching events. If that worst-case scenario occurs, artificial structures like these will become homes for reef fish and other marine animals.
Will the REEFrame structures affect surf breaks?
The structures won’t affect surf breaks. The structures will be placed at about 60 feet deep because the law requires that the tops of the nurseries be no shallower than 50 feet. They will be about six feet high and about ¾ mile offshore. The team will select the specific location after soliciting input from the community.
How will the partners involve the local community?
The team will solicit input from local cultural organizations to learn from ocean users, incorporate historical Indigenous practices, and educate the public about the project’s goals, science, and engineering. The team recognizes the cultural, economic, and biological value of the Waikīkī region and will minimize the impact while helping to restore this valuable resource.
Will anything show above the water’s surface?
No. The tops of the REEFrame structures will be about 50 feet under the water surface.
Will a large swell or extreme weather event cause the structure to move or damage anything around it?
No. It is specifically designed to be immoveable. In addition, a smaller pilot version didn’t budge during a large south swell.
Will the Waikīkī community be affected during construction?
Waikīkī residents will see the offshore vessels building the nurseries but will be otherwise unaffected.
How does REEFrame address issues around coral bleaching?
When extensive coral bleaching occurs, it can take many years for coral larvae to drift to the dead reef, settle, and grow into new coral colonies. Coral restoration seeks to hasten that natural process by transplanting coral colonies grown in laboratories or coral nurseries grown in other locations in the sea. The REEFrame modules are in deeper water that is cooler and therefore less susceptible to coral bleaching. As permanent nurseries, the modules will hold the transplanted coral colonies until they can be moved to reefs that need restoration – a similar approach to using tree nurseries to replant forests that have been devasted by wildfires.
