The Race to Rebuild the World’s Coral Reefs

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.