Lisa Carne was swimming through a bed of seagrass in northern Belize when she saw a hunk of elkhorn coral lying loose on the sandy bottom. She paused to look at it. With its rich amber color and antler-like branches, the fragment seemed alive despite having broken off from its mother colony. A professional diver, Carne was struck with an idea: What if she picked this up and moved it to a patch of dead reef? What if she did it over and over again? Could she help the reef recover more quickly?
Carne kept thinking about the fragment as she finished up her dive. The reefs close to her home, near Laughing Bird Caye National Park, in southern Belize, had recently been decimated by a hurricane. When she returned home, she sat down at her computer and started searching online for anything she could find on reef restoration.
A few years later, she began to fashion an underwater nursery near Laughing Bird Caye. Borrowing techniques from academic research, she used rebar and steel mesh to make a pair of underwater tables. She would swim around the reefs she had identified as resilient with a pair of pruning shears, cutting small chunks from healthy colonies. She brought each one to the shallows long enough to glue it to a concrete disk, then “planted” the fragments underwater on her metal tables. Slowly, they grew. Then she started transplanting her corals directly onto the reef.
Today, Carne’s nonprofit, Fragments of Hope, works with local fishers to identify promising spots and track the fate of every piece of coral they place on the reef. And it ranks among the most successful and longest-running coral restoration programs in the world. When I spoke to Carne on Zoom last fall, she had set her virtual background to show the fate of her first plantings on the dull gray rubble of dead reef. Branching corals the color of mustard filled the frame. “You can’t count that!” she said proudly, gesturing at the dense thicket behind her.
Yet for all of its success, Fragments of Hope’s program is still incredibly small. It has taken Carne and her team more than a decade to plant 160,000 coral fragments on less than 9 acres of reef. Worldwide, reefs cover an area millions of times that size. As Greg Asner, a researcher at Arizona State University who directs a global coral mapping program, put it, “No coral restoration projects of any kind or anywhere have been done at a scale that would really save a reef. Coral restoration has not summed up to even 1/100,000th of the area of shallow coral reefs worldwide.”
Coral reefs anchor some of the most vibrant ecosystems on the planet, home to a quarter of the oceans’ biodiversity in a tiny fraction of their total area. Half a billion people worldwide depend directly on reefs to protect their coastlines, support local fish populations, and attract tourists. But in the past 70 years, pollution, overfishing, and climate change have killed off half of the world’s reefs. By the end of this century, we may be speaking about healthy coral reefs in the past tense.
For years, Carne and others in the coral restoration field struggled to attract major funding for their efforts. That appears to be changing. In 2020, the insurance company Swiss Re crafted a policy to pay out nearly $1 million to send teams of divers to stabilize and replant corals that had been ripped out by a hurricane along the shoreline near Cancún, Mexico. Last year, the United States’ Defense Advanced Research Projects Agency issued a request for multimillion-dollar proposals for reef-building projects to protect US military installations.
Scientists, too, are coming around to the idea of large-scale experiments that might improve reefs’ resilience. For a long time, the sheer scale of reef systems made many people reluctant to contemplate regrowing corals. “It seemed like it was poking around the edges of the problem,” says Joanie Kleypas, who studies reefs and climate change at the National Center for Atmospheric Research.
Emboldened, scientists have been crossbreeding wild specimens taken from hundreds of miles apart to try to create hardier, heat-resistant variants. They have been freezing key samples of genetic material so that the scientists of the future can try to bring back some of the genetic diversity lost due to climate change. Ruth Gates, the late coral biologist and director of the Hawai‘i Institute of Marine Biology, told the The New Yorker in 2016 that she couldn’t bear the idea that future generations may not experience coral reefs: “We’re at this point where we need to throw caution to the wind and just try.’’ To rebuild reefs at scale takes a different kind of effort—and, perhaps, a different kind of person.
It was a balmy December evening at the Florida Sea Base, a STEM-themed retreat built in the Florida Keys in the 1990s that belongs to the Boy Scouts of America. Pastel-colored boys’ and girls’ dormitories overlooked a canal leading to the Atlantic. I was there to attend a workshop with 19 fledgling “coral gardeners,” who were seated at a row of long picnic tables, shaking off that first-night-of-summer-camp awkwardness with pizza and alcohol. Along with a team from Dry Tortugas National Park, 70 miles offshore from Key West, our group mostly consisted of emissaries of tiny NGOs from beautiful places reliant in some way on the people who could afford to visit. They were listening, rapt, to a small man with a Santa Claus beard. This was David Vaughan, the man we had all come to learn from. As the founder of the Plant a Million Corals Foundation, he is the closest person the field has to an industrialist-in-waiting.
Vaughan, who is 68, is slight and wiry, with intense blue eyes and sun-bleached shoulder-length hair swept back over a large bald spot. While many coral scientists are ecologists and geneticists whose field work is a balance of lab and reef study, Vaughan likes to say he spent his career as an aquaculture scientist “diving in 5 feet of muddy water,” honing techniques to grow shellfish bigger, faster, and cheaper. Between sips from a mug of red wine, he blitzed through his 40-year career as a businessman learning how to cultivate oysters, shrimp, and fish and turn a profit. His goal today is still, simply, scale; only this time he wants to bring the principles of industrial production to coral restoration.
In 2003, Vaughan became the director of the Keys outpost of the Mote Marine Lab, an independent research and education nonprofit headquartered in Sarasota. At first, the lab grew racks of coral the way aquarium hobbyists often did: Start with a piece the size of a golf ball, cut it in two and mount the halves on small ceramic discs, and wait months or even years for the pieces to grow back.
One day, Vaughan was cleaning an aquarium tank when he noticed a stray piece of coral the size of a silver dollar toward the back. He yanked it and heard a crack. A fragment came free in his hand, and a dozen polyps were left behind where the coral had fused to the glass. “Cracked into pieces, waving their tentacles at me,” Vaughan said. He figured the polyps were goners. He placed the fragment he’d broken off in another tank, where he thought it was large enough to perhaps survive and regrow. A few weeks later, he checked on it. Instead of seeing the ragged edge of bare, white coral skeleton, he found that new coral had completely grown over the damage—far faster than he’d imagined possible. He ran through the lab to see the old tank; each of those single polyps had multiplied, and the colony had grown to the size of a dime in weeks instead of years. “Like any good scientist,” he says, “I grabbed a scalpel, and I did it again.”
Vaughan called this technique “micro-fragmenting,” and he quickly sought to reproduce the results with as many species of coral as possible. It turned out that researchers at other labs had noticed a similar pattern—cutting coral into smaller pieces could boost its growth rate. Still, it took years for the significance of these early experiments to sink in. When Vaughan and colleagues at the Hawai‘i Institute of Marine Biology published a joint paper in 2015, they found that micro-fragmenting could make some corals grow as much as 40 times faster than they otherwise would.
One morning, Vaughan led the group outside, past the boys’ and girls’ showers to the edge of the mangroves lining the canal. Gravel crunched underfoot as we approached three rows of rectangular, blue plastic tanks resembling elevated kiddie pools. Vaughan explained that this was the “coral nursery” he’d built for the Sea Base. Peering down through a few inches of gently burbling saltwater, I saw what looked like trays of miniature hors d’oeuvres on porcelain plates—thousands of pieces of brown and purple coral, each the size of a large nailhead, their tiny barbed tentacles reaching toward the surface.
As we squinted to make out individual polyps, Vaughan marveled out loud about the quirks of coral biology. “A coral is a plant, an animal, and a microbe all mixed into one,” he explained, oversimplifying a bit—the algae in corals are not technically plants. Coral colonies are made up of genetically identical polyps, with tentacles to grab nutrients suspended in the water and digestive systems that secrete a skeleton beneath them as they grow. Corals provide a safe, well-lit habitat for symbiotic algae called zooxanthellae that use photosynthesis to produce essential nutrients and sugars for their hosts, and thousands of types of microbes. Moving water, Vaughan said, keeps the whole ballet going, providing the energy to push nutrients and gases across the mucous membranes of every coral cell.
Vaughan has been refining his microfragmenting process for 15 years, chasing both speed and savings, but he ran into issues with the basic supplies for the trade. For starters, the tanks were all wrong. “A farmer wants to see his crops all the time,” he complained; his tanks were made of opaque blue plastic. Since corals are factories for photosynthesis, the tanks should be clear, shaped in a way that allows you to mimic the ebb and flow of the surf.
While Sea Base staffers explained how to monitor and clean the tanks, Vaughan hovered around the edges, talking a novice through the proper technique to siphon debris out with a hose. (“Outside, now go low? Yeah, that’s it.”) He slid around a picnic table to peer through a microscope at the mucus on a newly cut micro-fragment. (“Let me see how that coral’s doing.”) He wore black Crocs sandals, synthetic khakis with zip-off lower legs, and a nylon safari shirt, unbuttoned halfway down his chest and embroidered with the logo of Plant a Million Corals.
Nothing got Vaughan so excited as recounting the hacks he’d developed to make things cheaper. At first he’d used ceramic plugs that aquarium suppliers sold for 25 cents apiece, until he took stock of the implications: “To plant a million corals, I’d have to raise a quarter of a million dollars!” he said with alarm. He decided to make his own plugs, but he needed the right mold.
One day, Vaughan was stewing on that challenge, bored while some students and interns were cutting corals, when he looked down at the perforated black rubber floor mat underfoot, like the ones you see in restaurant kitchens. “I go, ‘There it is!’ So I picked up the mat, and we poured the little holes, popped ’em out, then the next day we poured the big holes, put the stems we had back in, and we were making coral plugs at one quarter of a cent each”—a hundredth of the cost. Now he’s trying to shrink the size of the ceramic plugs so he can fit more of them into each tank and cut down on the operation’s biggest costs—the tanks themselves and the labor to keep them running.
With 12 trays per tank, that meant close to 4,000 corals in each one. The numbers matter, because Vaughan wants to make these nurseries fully modular—an affordable, off-the-shelf kit for coral farming. By packing all the necessary tanks, plumbing, and solar power to run the equipment into a shipping container, he hopes to make it possible to start cutting and growing corals anywhere with a water supply in a matter of days. Early prototypes of his Coral Restoration Units cost upwards of $200,000; he wants to cut the costs in half.
One afternoon, Vaughan played crossing guard as he jogged us across US Route 1 into an open field that had once been the site of a large shrimp hatchery where he hoped to build a roadside demonstration farm. The Keys’ landmass is made of ancient, fossilized reef, and some of its polyps and striations were visible through the grass. Near a stand of Australian pines were three half-packed shipping containers holding the guts of three future Restoration Units.
One of Vaughan’s first customers, Marissa Myer, had come to the workshop to see how her planned nursery, destined for Puerto Rico, was coming together. Vaughan enlisted volunteers to set up the tanks so he could visualize the plumbing he’d need. On her phone, Myer showed the group a digital rendering of the nursery she’d used to try to persuade the homeowner’s association of an upscale housing development to lease coastal land to her. In the image, string lights twinkled over an array of tanks perched on white sand and flanked by potted plants.
Most of the rest of the group was still figuring out how to pay for a Restoration Unit, or determining if it made sense to try a land-based nursery at all. There were the two Canadian marine biologists who’d landed in Antigua and started a field nursery with money they’d raised from patrons at an exclusive country club. An artist was building an electrified underwater coral sculpture as a memorial for her patron’s late daughter.
The person whose project came closest to marrying Vaughan’s methods with the money to pull it off was marine biologist Andrea Caicedo Gonzalez, who was preparing for “A Million Corals for Colombia,” an initiative of Colombia’s president, Iván Duque, and its Ministry of Environment and Sustainable Development. The nonprofit where she works, Corales de Paz, had 16 months to go from an underwater nursery that produced 25,000 corals a year to building a network of trainees doing micro-fragmentation across a dozen sites. Caicedo Gonzalez couldn’t help but notice that the project didn’t budget yet for “outplanting” the corals they grew in nurseries back onto reefs. She was debating the ethics of taking money from oil and cement companies, but she hoped to line up another grant from Chevron to finish the work.
The landscape of coral restoration funding has a take-what-you-can-get quality. Vaughan has discussed a dive and documentary with Leonardo DiCaprio and Richard Branson. And he’s consulted for Mohammed bin Salman, the crown prince of Saudi Arabia, who is now at work on a project set to add 2 million coral pieces to nearly 300 acres of reef. If only the process were cheaper, the money might be easier to find—and easier to say yes to.
David Vaughan grew up in suburban New Jersey and spent as much of each summer as he could with his head in the Atlantic Ocean, near his family’s house in Cape May. Vaughan’s father worked in fundraising for Fairleigh Dickinson University, and when Vaughan was 13, he tagged along with a group of scientists on a research trip to the US Virgin Islands. “We started going around Saint Croix, looking for new species and knocking pieces off with a prospector’s hammer,” Vaughan said. (Most major laws that protect marine species were not passed until the 1970s.) He came home mesmerized by coral.
Vaughan earned his PhD in botany at Rutgers, studying algae and seagrass. He soon discovered that his work on micro-algae was directly relevant to the nascent industry of farm-grown clams, which feed on the tiny organisms. Vaughan began drafting plans to build a hatchery. When his efforts to create a million-dollar facility ran into roadblocks, he decided to try rigging together a temporary clam farm inside three shipping containers. To his surprise, his DIY operation produced three times as many juvenile clams as the hatchery’s business plan had called for. Vaughan scrapped his original vision and stuck with shipping containers. “It became one of the first ways I was able to say, ‘We can do this cheaper,’” Vaughan told me.
He spent most of the first half of his career at Harbor Branch Oceanographic Institute, a marine research center with a small business incubator he started on Florida’s Treasure Coast. He developed a reputation there for being pragmatic, entrepreneurial, and a bit quirky; during one field project, he and his wife and young daughter spent the season living out of an Airstream van and sleeping in a loft on the back.
At Harbor Branch, he oversaw construction of a new 30-acre aquaculture campus, with hatcheries for oysters, clams, and shrimp. As Florida’s clam industry ballooned, Harbor Branch became its largest hatchery.
One day, someone left a freshwater hose running overnight in a saltwater shrimp tank. When Vaughan discovered the hose in the morning, he expected the shrimp to be dead. Instead, they were doing fine. Shrimp have been known to tolerate low-salinity water during the rainy season, though it hampers their growth and makes them more susceptible to infections. “Dave looked at it differently,” said John Scarpa, a shellfish biologist who worked at Harbor Branch. Vaughan didn’t need the shrimp to lead long, full lives—he simply needed them to reproduce. Using freshwater or low-salinity water meant he could start growing shrimp not just on expensive coastal land but in the middle of Florida.
In the late 1990s, Vaughan learned that Aqua Life, an ornamental-fish-breeding operation on a small island in the Bahamas, was shutting down. Harbor Branch made a bid to buy what was left, and a month later, 22,000 orange and white clown fish in different stages of development arrived in Florida by plane, while 380 tanks made their way over on a chartered barge. Vaughan decided to sell the aquarium fish directly to pet stores. When Finding Nemo caused a spike in demand for clown fish in 2003, Vaughan’s company ended up selling 25,000 of them a month. It also got into the coral business.
One day, Vaughan gave a tour of his aquaculture operation to the conservationist and filmmaker Philippe Cousteau Jr., grandson of Jacques, the famous French ocean explorer. When Cousteau got to the coral tanks, he was struck to see rows and rows of hand-sized fragments destined for pet stores, when most of the corals in the nearby Florida Keys were dead. As Vaughan recalled, Cousteau said, “Dude, you don’t get it. You need to be doing this for the reef.”
Vaughan began to realize how much coral research could benefit from advances in aquaculture. The industry had spent decades refining dozens of small tasks and processes to raise marine life efficiently. “There’s no reason we can’t use the same model for clams or oysters or fish and apply it to coral,” he told me.
He’s been amazed to observe his coral fragments repair themselves and grow. Vaughan’s hypothesis is that this healing mechanism originated in the intense competition between life forms on a reef. Parrot-fish, which can graze on algae that grow on the surface of polyps, sometimes bite off a chunk of the coral itself; perhaps corals evolved a way to repair the damage as quickly as possible, so that sponges and algae couldn’t gain a foothold in the center of a colony.
But for all of Vaughan’s success in growing coral quickly, cheaply, and effectively in plastic tanks, coral fragments still need to survive once you put them back in the sea.
Vaughan discovered that if he planted many micro-fragments of the same genotype next to one another, they’d eventually fuse together. In 2013, he got permission to try this technique on bleached stony corals off the coast of Big Pine Key and led a team that planted 1,300 micro-fragments in clusters. More than 80 percent survived an outbreak of stony coral tissue loss disease, a mysterious pathogen that has affected populations of more than 30 species across the Caribbean. Over the years the clusters completely fused together, and in August of 2020 they spawned, unleashing a wave of tiny pink coral gametes under a full moon. Vaughan marveled at the achievement. “They’re the age of a kindergartner, but somehow they got together and circulated the message to start making genetic material.”
But the odds of survival are not in coral’s favor. Even where the threats of disease or bleaching aren’t as urgent, the mechanisms underlying successful coral restoration can be hard to pinpoint. In Indonesia, where many coral restoration projects have been undertaken since the 1990s, the marine biologist Tries Razak says most amounted to “just putting concrete on the sea bottom.” Razak is in the middle of a three-year survey visiting sites all over the country. In some cases, the reasons for failure are obvious: Corals were planted on piles of unstable rubble left behind by dynamite fishing or massive storms and were quickly buried in sediment.
Others are more mysterious. Razak showed me a triptych of photos from a research study that included sites in Indonesia’s Komodo National Park, all taken five years after divers had assembled rock piles on the sea floor to create new reef habitat. In one, the underlying structure was scarcely visible, with huge plate corals and branching corals covering its surface in resplendent pinks and yellows. At another site, it was as though the rocks had been piled up the day before, covered only in a thin layer of algae. The third was completely buried in sediment.
Lisa Carne has brought Vaughan down to Belize three times to lead trainings on coral restoration and aquaculture. But where he focuses on trying to “plant a million corals,” she says, “we’re looking backwards at our data and talking about the opposite: If you pick the right site and the right corals, and everything else lines up, you shouldn’t have to keep adding in one spot.” In other words, what’s the minimum amount of coral you can outplant on a given reef to help nature take its course?
Vaughan, Carne, and others are all trying to find ways to improve corals’ odds of survival, tracking the performance of different genotypes, or the influence of current, depth, temperature, and the presence of fish and other aquatic species on the fragments they outplant. Depending on your point of view, coral restoration is either a profoundly pessimistic or optimistic undertaking. To some it suggests we’re past hoping humans will act forcefully enough to curb water pollution, designate new marine protected areas, or, above all, slash emissions to help natural reef systems withstand global warming. To others, restoration serves as penance for the damage we’ve already done, and a way to maximize our chances of shepherding corals through the Anthropocene.
In the grand scheme of things, corals will survive. Reefs are as old as almost any life in the sea, going back to the very first photosynthetic organisms on the planet—cyanobacteria that began secreting calcium carbonate more than 2 billion years ago. The photosynthesis on these early reefs drove the creation of an oxygen-rich atmosphere that would sustain advanced life. Corals have undergone mass diebacks before, and in geologic time, they rebound quickly. But quickly is measured in millions of years.
Vaughan sees his tinkering with coral as being in the service of a world where humans are willing to address the root causes of its distress. When he imagines people visiting his future roadside attraction, it isn’t to make them see the wonders of micro-fragmenting but rather to understand the bigger picture. “You want to know that when they go home they’re going to vote correctly, or recycle better, or lower their thermostat, or eat down the food chain,” he says. Like polar bears or any species in peril, corals are simply an indicator, Vaughan says. “And what that’s saying is, ‘You’re next.’”
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