That year high sea temperatures caused massive and severe coral bleaching in the Keppel Islands, in the southern part of the GBR. The damaged reefs were quickly smothered by a single species of seaweed – an event that can spell the total loss of the corals.

However, a lucky combination of rare circumstances meant the reefs were able to achieve a spectacular recovery, with abundant corals re-established in a single year, says Dr Guillermo Diaz-Pulido, from the ARC Centre of Excellence for Coral Reef Studies (CoECRS) and the Centre for Marine Studies at The University of Queensland.

“Three factors were critical. The first was exceptionally high re-growth of fragments of surviving coral tissue. The second was an unusual seasonal dieback in the seaweeds, and the third was the presence of a highly competitive coral species, which was able to outgrow the seaweed.

ARC Centre of Excellence

Algal overgrowth

“But this also all happened in the context of a well-protected marine area and moderately good water quality”, said Dr Diaz-Pulido.

“It is rare to see reports of reefs that bounce back from mass coral bleaching or other human impacts in less than a decade or two,” he adds

“The exceptional aspect was that corals recovered by rapidly regrowing from surviving tissue. Recovery of corals is usually thought to depend on sexual reproduction and the settlement and growth of new corals arriving from other reefs. This study demonstrates that for fast-growing coral species asexual reproduction is a vital component of reef resilience” says Dr Sophie Dove, also from CoECRS and The University of Queensland.

“Coral reefs globally are increasingly being damaged by mass bleaching and climate change, and their capacity to recovery from that damage is critical to their future,” explains Prof. Ove Hoegh-Guldberg of CoECRS and The University of Queensland. “Our study suggests that managing local stresses that affect reefs such as overfishing and declining water quality can have a big influence on the trajectory of reefs under rapid global change.”