NOAA and Partners Launch Next-Generation Coral Restoration Following Florida Coral Bleaching

Healthy coral reefs are vital to the survival of thousands of marine species and provide $6.3 billion in local sales and 71,000 jobs annually (PDF, 29 pages). But rising ocean temperatures are pushing these ecosystems to the brink. That's why NOAA is investing in cutting-edge technology to create more heat-resilient corals.

In the wake of Florida's severe 2023 coral bleaching event , NOAA and its partners are launching new strategies to restore reefs and prepare them for a hotter future. At the heart of this effort is NOAA's Mission: Iconic Reefs . It's an ambitious long-term initiative to boost coral cover from just 2 percent to 25 percent across seven key sites in the Florida Keys National Marine Sanctuary .

In 2023, the Office of Habitat Conservation awarded $16 million to the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science for a project applying emerging science and technology to coral breeding and restoration. The goal: to grow and outplant corals better equipped to withstand future bleaching. Key approaches include:

• Selective breeding of corals that survived the 2023 bleaching to pass on heat-tolerant traits
• Breeding Florida's remaining elkhorn corals with heat-adapted corals from warm-water reefs in Honduras (this work was funded through a previous NOAA award )
• Pairing baby corals with beneficial symbiotic algae and probiotic bacteria to improve their ability to withstand future bleaching
• Bioprinting coral babies-embedding coral larvae, algae, and bacteria in a protective hydrogel to increase settlement and survival
• Rearing baby corals in high-temperature environments to condition them to tolerate warmer waters

This work is funded through the Infrastructure Investment and Jobs Act , which is also supporting similar efforts by other Mission: Iconic Reefs partners. Mote Marine Laboratory and the Coral Restoration Foundation are:

• Breeding and rearing coral species that withstood the 2023 bleaching
• Accelerating the outplanting of massive brain and boulder coral species, which fared much better than branching corals like elkhorn and staghorn during the 2023 bleaching
• Expanding the capacity to store genetically diverse and heat-tolerant corals for future restoration

Many other partners and individuals support the Mission: Iconic Reefs program.

Finding a New Way Forward

Before the 2023 bleaching event, Mission: Iconic Reefs prioritized the outplanting of branching corals like elkhorn and staghorn at reefs in Florida Keys National Marine Sanctuary. But a 2024 assessment on outplanted corals revealed that fewer than 22 percent of staghorn corals survived the bleaching, and less than 5 percent of the elkhorn remained alive.

In the face of this devastating impact, NOAA and its partners-alongside coral restoration groups from around the world-came together to chart a new path forward.

"I've never seen so many dedicated people rise to the occasion and say, 'We have to try harder,'" says Maddie Cholnoky, Mission: Iconic Reefs implementation manager. "These incredible organizations are sharing knowledge, science, and lessons learned. It's inspired us to take those insights and help create adaptive tools for our partners and for the mission."

In February, NOAA staff joined partners from the Coral Restoration Foundation, Mote Marine Laboratory, and Reef Renewal USA to mark the fifth anniversary of the initiative. They celebrated by outplanting new corals propagated from survivors of the 2023 bleaching event.

"We've done a fantastic job across so many organizations of preserving genetic diversity, which will be important in future outplanting efforts," says Dr. Katey Lesneski, Mission: Iconic Reefs's research and monitoring coordinator. "We have a lot of confidence that the corals will continue to do well even in future warming conditions."

Advancing Techniques for Coral Reproduction

Andrew Baker, a professor at the Miami's Rosenstiel School of Marine, and Atmospheric, and Earth Science, is leading the University of Miami project. It brings together researchers and restoration practitioners from the university and 10 other organizations to transform the way restoration is conducted in Florida.

The project team will ramp up the use of coral spawning events to breed and rear new generations of corals that are genetically diverse. It will also target coral parents that are heat resistant. They will use sexual reproduction and leverage new technologies to enhance the growth of more bleaching-resistant corals. The team aims to significantly increase the number of new resilient corals available for outplanting.

Previous restoration efforts relied heavily on asexual reproduction to grow new corals, essentially outplanting coral fragments broken off from adult corals. This method is effective in increasing coral cover on reefs, but limits the production of new coral diversity. It can make reefs more vulnerable to mass bleaching events and other disturbances because many of the outplanted coral fragments are genetically identical.

"Flonduran" Coral

The project team is also crossing heat-tolerant Florida corals with corals from unusually warm reefs in Honduras.

"A couple of years ago, we heard of a reef in Tela, Honduras, that was largely unknown to science," says Baker. "Despite the water there being much warmer than Florida's and heavily polluted by a century of industrial agriculture, the reefs there are thriving. We sourced parents from the reefs and successfully spawned them with our team.They were then bred with Florida corals and now we have a hundred babies almost a year old that are getting ready for outplanting. We call these our 'Flonduran' corals."

The Florida Fish & Wildlife Conservation Commission gave the University of Miami permission to begin outplanting the Flonduran corals in Florida's state waters outside of national parks and sanctuaries. Dr. Baker is in talks with NOAA staff at the Florida Keys National Marine Sanctuary to determine if the Flonduran corals might also be suitable for Mission: Iconic Reefs.

Helping Baby Coral Become More Bleaching Resistant

To further increase the heat tolerance of baby corals, researchers are provisioning them with beneficial algae and bacteria.

All reef-building corals rely on symbiotic relationships with single-celled dinoflagellate algae to survive. The algae live within the coral tissue where they photosynthesize, converting sunlight into sugars, which nurture the coral. But when ocean temperatures rise, this delicate partnership breaks down. The algae begin to produce toxins instead of sugar; the coral loses its food source and begins to lose its color as it expels the toxin-producing algae; and bleaching occurs.

To combat this, Baker's lab has spent years researching heat-tolerant algae. Now, they're introducing those algae to corals during the earliest stages of life. "We're studying how long these partnerships last and how much more heat tolerance they offer when the corals are outplanted in the wild," says Dr. Andrew Baker. "We are finding that these partnerships are pretty long lived, especially in areas affected by chronic stressors."

Researchers from the Smithsonian Marine Station in Fort Pierce and the Rosenstiel School team are investigating whether supplying baby corals with probiotic bacteria can prevent bleaching. When coral becomes heat-stressed, its algae produce harmful toxins that can trigger bleaching. The added bacteria appear to help detoxify some of these damaging compounds, reducing stress on the coral and potentially increasing survival rates.

Dr. Baker's team is also testing whether early exposure to high temperatures can help "train" corals to better tolerate heat. "By conditioning corals at the larval stage, we can cause them to modify their biology in ways that improve thermal tolerance," says Baker. "Some of these changes can be very long lived. These training conditions can also help heat-tolerant algae and probiotic bacteria get a head start in young corals."

Producing Heat-Tolerant Corals on a Massive Scale

To meet the initiative's ambitious goals, restoration practitioners will need to grow and outplant millions of corals. The Rosenstiel School team is developing a new bioprinting technique to help meet that demand.

This technology will print tiny hydrogel bubbles-each containing coral larvae, seawater, symbiotic algae, probiotic bacteria, and compounds that encourage settlement and growth. "These hydrogel capsules act as temporary life support bubbles, increasing the young corals' chances of survival and helping baby corals settle in predictable ways that can help scale up coral production," says Baker.

"Imagine something like an industrial inkjet printer laying down a grid of 1,000 by 1,000 hydrogel bubbles on a tile," says Baker. "The tiles are pre-scored with lines so that they can easily be snapped apart, allowing them to be easily propagated, transported, and deployed on reefs, potentially using automated robotics. It may sound like science fiction, but it's the direction we have to move in to have a chance at doing this at the scale we need."

The University of Miami Rosenstiel School aims to have bioprinting and its other new technologies fully up and running by 2027.

Outplanting Massive Corals

Following the 2023 bleaching event, NOAA and its partners observed that slower growing massive coral species-like brain, boulder, and star corals-fared better than fast-growing branching corals. While outplanting these species was already part of the initiative's long-term restoration plan, their apparent resilience prompted an urgent pivot.

"We were just starting to build our stock of these species before the bleaching event, so the very first thing we did was outplant about 10,000 of these corals in all seven reefs," says Phanor Montoya-Maya, reef restoration program manager for the Coral Restoration Foundation.

"Mote has dramatically increased the production and restoration of massive form coral," says Jason Spadaro, coral reef restoration program manager for Mote. "Massive form corals tend to be more thermally resilient than branching species, but they take longer to grow and occupy limited nursery space. Our goal is to identify the point where we can maximize production and growth and meet the demands for an increased scale of restoration."

Mote and the Coral Restoration Foundation are also growing and outplanting fragments from branching corals that survived the bleaching event. The Foundation is changing its strategy from planting a single species of coral over a broad area to the "applied nucleation method"-planting multiple coral species in tightly packed clusters over a smaller area. "So far, this method has shown high survivorship and a faster pace of growth," says Montoya-Maya.

Meanwhile, Mote is rearing Caribbean king crabs, which graze on certain algae species that compete with corals for space and light. The crabs help maintain healthier reef environments for coral growth and settlement.

Making a Noah's Ark for Coral

To safeguard Florida's coral diversity, partners like the Coral Restoration Foundation, Mote, and the Florida Aquarium are expanding gene banking efforts. Long-term storage of genetically diverse coral specimens could one day help rebuild reefs after future major disturbances.

Earlier this year, Mote announced that it is using cryopreservation to freeze coral sperm at ultra-low temperatures, allowing it to be stored indefinitely.

"Cryopreservation is really exciting because we can save the samples 2 days from now or, in theory, 200 years from now," Dr. Erinn Muller, Mote's director of coral health & disease , told a reporter from the Sarasota Herald-Tribune. In the future, the sperm could be mixed with eggs from corals from different locations to create genetically diverse corals better able to survive ecosystem stressors.

Mote plans to hold up to 50 diverse genotypes of the more than 60 different coral species native to Florida-an insurance policy for the future.

"When the scale and scope of the challenges facing Florida's corals seem insurmountable, partnerships to leverage unique strengths become even more critical to move the science and practice of coral restoration ahead," says NOAA Marine Habitat Resource Specialist Michelle Loewe. We are fortunate to partner with organizations who continue to show up and work together to drive innovation."

Partners on the University of Miami award include:

• Mote Marine Laboratory
• Nova Southeastern University
• The Florida Aquarium
• Philip and Patricia Frost Museum of Science
• Smithsonian Marine Station
• The Reef Institute
• Reef Renewal USA
• SECORE International
• Biscayne National Park
• AECOM