Restored coral reefs can bounce back in just four years

Coral reefs are vital underwater ecosystems teeming with life. Yet, climate change and human actions threaten their very existence. This is cause for alarm as coral reefs provide a haven for countless marine creatures. 

Not all hope is lost. Scientists recently discovered a surprising power of coral reefs: amazing regenerative abilities. With a little assistance, restored coral reefs can bounce back in just four years, becoming vibrant once again.

Restoring reefs with coral transplants

The study focused on the Mars Coral Reef Restoration Programme, one of the world’s largest reef restoration projects. The program restored coral reefs in two Indonesian islands. 

The restoration method involved structures called “reef stars” – hexagonal metal frames filled with sand. Each frame provides a home for 10-15 pieces of coral collected from nearby healthy reefs. These coral fragments come from several different types of branching coral naturally found in the area.

Careful maintenance 

The restoration process involves placing these reef stars in large groups across a designated area. But simply placing them isn’t enough. To ensure the coral thrives, the frames are brushed regularly to remove algae, and any dead coral pieces are replaced. 

This careful maintenance is especially important in the first few months after the coral is transplanted, giving it the best chance to grow and establish itself.

Carbonate budget of restored coral reefs

Scientists studied how well restored coral reefs were doing by looking at their “carbonate budget.” This refers to the balance between how much calcium carbonate the reef is making and how much it’s losing. 

Calcium carbonate is a building block for corals, and a healthy reef will be making more of it than it’s losing.

“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,” noted study lead author Dr. Ines Lange from the University of Exeter. 

Four years after the restoration efforts began, the reefs were doing much better. They had more coral, were more complex, and were building calcium carbonate at a similar rate to healthy reefs. 

“We found that restored coral reefs can grow at the same speed as healthy coral reefs just four years after coral transplantation. This means that they provide lots of habitat for marine life and efficiently protect the adjacent island from wave energy and erosion,” said Dr. Lange.

Restoration challenges

Coral restoration projects often use fast-growing branching corals because they help reefs recover quickly. However, these corals are also more likely to die from bleaching caused by rising water temperatures. This could make the restored reefs weaker in the long run.

While branching corals create good homes for fish and other sea creatures, researchers worry that relying on them too much might be risky. They recommend using a wider variety of coral types during restoration, similar to what’s found on healthy reefs. 

This mix would include massive, encrusting, and plating corals, which are all better at surviving bleaching events.

The researchers also express that there’s no single perfect way to restore reefs. The best approach will depend on the specific location, the types of coral available, and how well the surrounding environment is protected. 

Future of coral reef restoration

The study has demonstrated that actively restoring reefs by transplanting coral can significantly improve their health. 

“This is a really encouraging discovery. If we can maintain climate conditions that allow for coral survival, it’s possible to restore even very damaged reefs back to healthy, functional systems within relatively short periods of time,” noted Dr. Tim Lamont of Lancaster University.

The study is a wake-up call. We can revive our coral reefs, but we must act swiftly. By implementing a multi-pronged approach of restoration, environmental protection, and climate change action, we can ensure the future of these underwater wonders. 

The study is published in the journal Current Biology.

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