Coral Reef Restoration Can Help Provide ‘Full Recovery’ Within Four Years, Study Finds

One of the most visible indicators of ocean surface temperature warming due to climate change is the bleaching of coral reefs. Environmental changes like warming waters can cause corals to expel the algae that live on them and provide them with nutrients, turning the corals white.

A new study has found that, while most of the world’s coral reefs are currently damaged or under threat, efforts to restore them can revitalize important ecosystem functions remarkably quickly.

“We found that restored coral reefs can grow at the same speed as healthy coral reefs just four years after coral transplantation,” lead author of the study Ines Lange, an associate professor of marine conservation and management at University of Exeter, said in a press release from Cell Press. “This means that they provide lots of habitat for marine life and efficiently protect the adjacent island from wave energy and erosion. The speed of recovery that we saw was incredible. We did not expect a full recovery of reef framework production after only four years.”

The study was conducted through Indonesia’s Mars Coral Reef Restoration Programme and involved the restoration of coral reefs that had been badly injured by blast fishing three or four decades earlier by adding substrate and transplanting corals.

Before scientists intervened, the reefs had not demonstrated any signs of recovery. This was because loose coral rubble was preventing the survival of coral larvae.

In order to consolidate the rubble, the researchers added steel structures coated with sand, which provided a framework for the transplantation of coral fragments.

To find out how fast the restored sites would recover, the research team looked at the carbonate budgets of a dozen sites — restored at various times as much as four years ago.

“Corals constantly add calcium carbonate to the reef framework while some fishes and sea urchins erode it away, so calculating the overall carbonate budget basically tells you if the reef as a whole is growing or shrinking,” Lange said. “Positive reef growth is important to keep up with sea-level rise, protect coastlines from storms and erosion, and provide habitat for reef animals.”

The study, “Coral restoration can drive rapid reef carbonate budget recovery,” was published in the journal Current Biology.

Research data showed that quick growth of coral transplants supports carbonate production and coral recovery. In only four years, a threefold increase in corals’ net carbonate budget was equal to those at healthy control sites.

However, restored reef communities differed from natural ones because during the transplantation process, branched corals were chosen over other types of corals.

The researchers pointed out that the differences “may affect habitat provision for some marine species and resilience to future heat waves, as branching corals are more sensitive to bleaching.”

The researchers said the findings showed that vigorous management can help improve coral reef resilience and revitalize ecosystem functions essential for marine life — as well as local communities — relatively quickly.

The team hoped that restored reefs would eventually begin to attract a more diverse array of corals.

They emphasized that the outcome in any particular location would depend upon restoration methods, environmental conditions and many other factors.

“These results give us the encouragement that if we can rapidly reduce emissions and stabilize the climate, we have effective tools to help regrow functioning coral reefs,” said study co-author Tim Lamont, a marine biologist at Lancaster University’s Lancaster Environment Centre, in the press release.