Scientists have uncovered an unlikely way to boost coral health to help it withstand times of heat stress - a good dose of probiotic bacteria.
The international team of researchers made the breakthrough soon after Australia's Great Barrier Reef weathered its third mass bleaching in five years.
The use of probiotics has been widely regarded as successful in improving human and animal health, but their use in marine ecosystems was largely unexplored until now.
"People may be surprised to find out that, just like us, corals rely on a host of good bacteria to help keep them healthy and, just like us, the balance between good and bad bacteria is often disrupted in times of stress," Great Barrier Reef Foundation Managing Director Anna Marsden said.
Stress-triggered unbalances can leave the coral more prone to infection and less likely to survive.
Under laboratory conditions, researchers experimented with injecting coral with beneficial microorganisms, but eventually settled on feeding them through their zooplankton prey.
The tiny plankton absorb the good bacteria through the water and the coral then dine on the enriched plankton - a bit like feeding them probiotic yoghurt full of good bacteria.
The team found these corals fared better in stress tests time and time again.
It is hoped the technology can be used to boost the health of artificially-reared coral used in reef restoration projects, which currently have a low rate of survival once introduced to the natural reef.
The technology will be used on these lab-reared coral within a year.
The team, led by Federal University of Rio de Janeiro Professor Raquel Peixoto, is currently testing which groups of good bacteria are the best for each coral species.
It is also investigating ways to scale up the application, such as delivering parcels of slow release probiotics to targeted reefs during times of heat stress.
Australian Associated Press