Repaired coral reefs will swiftly recover from damage

Research findings from a restoration project in Indonesia suggest that restored coral reefs can develop at a rate comparable to healthy coral reefs in just four years. Although quick recovery rates are anticipated, restored reefs tend to have lower species diversity compared to undamaged reefs, raising questions about their long-term survival under more extreme conditions like heat waves. Further studies are required to validate these findings.

Global coral reefs confront a variety of threats, from escalating sea temperatures and ocean acidification to human-related activities such as overfishing.

In the vicinity of Indonesia’s Sulawesi island, coral reefs suffered severe damage approximately three decades ago due to dynamite fishing, a method involving the use of explosives in water to catch large quantities of fish.

According to Tim Lamont from Lancaster University in the UK, “recovery from dynamite fishing does not occur naturally.” The aftermath of this fishing technique leaves a substantial amount of fragmented dead coral skeletons floating, hindering natural coral settlement and growth.

To facilitate the recovery of coral reefs, the Mars Coral Reef Restoration Program has undertaken efforts to restore reefs. As part of Mars’ sustainability initiative, they have deployed sand-coated hexagonal steel structures on the seabed and transplanted them with cuttings from healthy corals. Known as reef stars, these structures stabilize loose debris and promote coral growth.

Simultaneously, Lamont and his team have been monitoring the progress of these initiatives.

One measure of coral health involves examining if the coral’s limestone skeleton grows faster than it erodes. This metric, known as the carbonate budget, signifies the reef’s overall growth rate.

“Four years post the commencement of the restoration process, the reef exhibited growth rates similar to those of healthy reefs,” noted Lamont. “It’s a remarkably rapid recovery.”

However, the composition of the restored coral reef differed from that of a healthy reef, predominantly comprising branched corals. This variance is primarily due to the restoration technique employing branch corals that can be sourced from living corals, entail less damage, and readily adhere to steel structures.

“Given that branching corals are generally more susceptible to bleaching, variations in communities could result in differing resilience to future stressors, particularly heat stress,” stated team member Ines Lange from the University of Exeter in the UK. “We anticipate that larger and more covered corals will naturally rejuvenate and recover in the restored areas over prolonged periods.”

Lamont emphasized that under stable climate conditions, it is feasible to reconstruct these vital ecosystems. Nevertheless, continued research is essential to assess the recovery of species diversity and the resilience of coral reefs when compared to healthy reefs.

While acknowledging the positive outcomes, members like Michael Bode from Queensland University of Technology, Australia, voiced concerns about the scalability of such projects amidst escalating climate change, the primary threat to coral reefs.