Among a scattering of islands scattered like beads in the Indonesian shallows, an extensive experiment in coral restoration has revealed something amazing: With a gentle touch and a community to care for it, a reef can fully recovered from the devastation of blast fishing. four years.
The Spermonde Archipelago, which lies a dozen miles off the coast of South Sulawesi, Indonesia, has long been home to some of the most dynamic reefs in the world, where schools of fish rainbow across coral that covered the sea floor. But dynamite fishing turned parts of those wonders into waste. That was, until, in 2018, when academics, government agencies, nonprofits, and local communities came together to restore them with a new approach developed over years of testing and refinement. Now, a team of marine biologists and reef ecologists has released the first results in a series of studies examining the program’s achievements. the study room, published earlier this month in Current Biologyshows that the method can help rebuild reefs in just a few years.
“We always refer to corals, especially in reefs, as these slow-growing ecosystems that take a long time to recover, which they are,” said Rebecca Albright, a coral biologist at the California Academy of the Sciences who was not involved in the study. “To show that they can regain rapid growth within four years is therefore very encouraging.”
Advancing this recovery in Sulawesi is particularly important because the island is located in the middle of the Indonesian archipelago, and in one corner of the coral triangle. This region, and especially Indonesia, is home to the greatest concentration of reefs and coral habitat in the world. Yet many of these vibrant ecosystems have been pulverized by decades of fishermen dropping explosives into the water to find fish that they could then scoop out of the sea. With loose debris then left to tumble into the currents, corals had little hope of recovering on their own. Any coral spawn able to establish and grow tended to be crushed by errant rocks.
To overcome this, the Mars Coral Reef Restoration Program — a nonprofit organization funded by the Mars Corporation known for M&Ms, Twix and Snickers — has brought together recovery experts who have developed what they call the reef star: a six-legged steel spider covered in sand, to which are attached coral fragments harvested from nearby healthy reefs or found rolling with the tides. Restoration workers, often members of local communities, deploy across dozens of sites. These webs provide the protection and stability the transplants need to grow, while also settling the debris created by blast fishing. Without such help, researchers believe corals—those strange yet essential sea creatures—may never have returned to the damaged areas.
Within a year of placing the reef stars, the fragments grew into colonies. By year two, the branches of neighboring colonies expand into a marine embrace. By 2023, the former fragments have grown into orange bushes, broad yellow cushions, and writhing pink tentacles that explore trains of fluorescent fish.
The Ocean Agency
Scientific analysis confirmed what the eye could see. By measuring something called a carbonate budget—a way to understand how well a colony can grow its limestone skeleton in the face of erosive forces like fish, diversand passing vessels—researchers found that the growth rate for sites established just four years earlier matched that of healthy, undamaged coral growing nearby.
Studying this growth helps scientists understand how well a reef fulfills its role as the star of a healthy ecosystem that provides habitat for marine life. “The 3-D structure of the reef is basically the city where these animals live,” said Ines Lange, a coral reef ecologist and lead author of the paper. “So, providing an actively growing three-dimensional structure is the basis for this entire ecosystem.”
The rate and state of growth also reveals whether the reef can be expected to once again protect coastlines from storm surges and coastal erosion—and grow fast enough to keep up with rising seas to continue doing so. The results show that this will not be a problem in South Sulawesi. Other recovery effortslike that in the Florida Keys, tend to string a few strands of coral fragments or pepper the seabed with them in a way that felt to Lange “like a little little garden.” But at the Mars program sites, “It’s like they put a forest there.”
“I think it was the first time I saw a recovery site that was a proper reef,” she said.
These seashores are populated primarily by branching, tree-rich coral that emerges from the reef star arrays in the coastal plains. They have created a site that thrives with life that turns the aquamarine waters into a technicolor dreamscape. In general, the method has proven itself, even to those who see it unfold from afar.
“The Mars project has set the bar very high for how you can do evidence-based reef restoration,” said Lisa Bostrom-Einarsson, a coral reef ecologist at the University of Exeter.
Although not affiliated with the study, Bostrom-Einarsson collaborated with two of its authors on a previous paper. It is not surprising that the world of coral reef conservation remains small, despite the great need for its work.
Four years ago, Bostrom-Einnarsson put together a systematic and comprehensive review of reef restoration projects, which she is updating based on the progress made in such efforts worldwide in the intervening years. That background led her to conclude, after reading Lange’s paper, that “this is a gold standard study on a gold standard project.”
Ines Long
Yet Mars’ reef stars are best suited to places like South Sulawesi where the trauma is physical. When reefs are breached widespread blast fishing or plagued by shipwrecks – of which there is hundreds every year – the study shows the devices can help heal those injuries with surprising ease. But in areas such as the Great Barrier Reef which was created by rcurrent bleaching events that offer little of the reprieve that reefs need to recover, they can only do so much; the repeated heat waves spurred by increased temperatures make the water itself hostile to coral. Nevertheless, the Mars program attempt launched late last year to adjust his approach for Australia’s iconic reef. The types of coral most sensitive to warming are also those best suited to the Mars method.
In the waters off South Sulawesi, the recovery team chose branching corals because they make up the bulk of the region’s healthy reefs and because they grow quickly—Bostrom-Einarsson called them “weed coral.” But the tree-like Acropora cannot tolerate the heat like their massive, slow-growing cousins the brain coral can; Acropora are among the first to bleach when temperatures rise. So, while the marine meadows at the restoration sites have thrived in recent years, more needs to be done to make them resilient warm sea.
“You can put a bunch of coral back in place, but that doesn’t mean you’re building a resilient reef,” Albright said. “You have to have diversity.”
Lange said the Mars program strengthens ecosystems’ resilience, transplants massive corals and provides the surfaces they need to establish, establish and mature. This is just one area that reflects the responsive approach. Bostrom-Einarrson said that the Mars program brought about its efforts by listening to scientists, considering their evidence and tapping into their expertise.
But to avoid what Bostrom-Einarrson called “scientific colonialism” — in which researchers from well-funded institutions visit under-resourced areas to gather data before scurrying home — the Mars program has built partnerships with local communities and universities. They are involved in everything from building the reef stars and installing them to maintaining and monitoring restoration sites, all of which give them a sense of ownership over the project by making them guardians of the reefs.
And that may be one of the most important outcomes of a project like this. After all, coastal communities in places like South Sulawesi benefit the most of rebuilding the reefs that protect them from the storms and heaving sea which brings about climate change. But the researchers acknowledged that recovery efforts like these are only band-aids. They are not a substitute for reducing emissions and mitigating climate change so that reefs can escape the endless onslaught of bleach-inducing, coral-killing heat waves.
“We are not saying we can restore all the coral reefs in the world with this method,” said Lange. “But that doesn’t mean we shouldn’t do something on the scale we can to change something for a local community, because it makes a big difference to them.”
So, if only for that reason, these efforts matter—even in the wake of a warming world.
