The Race to Rebuild the World’s Coral Reefs

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.