Australian scientists have bred a heat-resistant coral which could help preserve the country's iconic reefs for generations to come by restoring areas devastated by mass bleaching.
Coral reefs are in decline worldwide due to increasingly frequent and severe bleaching events.
A survey of the Great Barrier Reef off Queensland's coast last month revealed bleaching had, for the first time, struck all three regions of the world's largest coral reef system.
CSIRO researcher Patrick Buerger says climate change is threatening the future of remaining reefs.
"Climate change has reduced coral cover, and surviving corals are under increasing pressure as water temperatures rise and the frequency and severity of coral bleaching events increase," Dr Buerger said.
The white skeleton of coral caused by extensive heat stress. Source: Chris Jones/CSIRO
With three mass bleaching over the past five years the barrier reef has not had enough time between events to recover.
Scientists hope by improving coral's natural heat tolerance they can reduce the impact of reef bleaching during summer marine heat waves.
The team isolated tiny algae which live inside coral tissue and exposed it to increasingly warmer temperatures over four years.
Called "directed evolution" the technique assisted the microalgae to adapt and survive in hotter conditions.
The experiments were conducted at the Australian Institute of Marine Science in a sea simulator. Source: Patrick Buerger/CSIRO
"Once the microalgae were reintroduced into coral larvae, the newly established coral-algal symbiosis was more heat tolerant compared to the original one," Dr Buerger said.
Fellow University of Melbourne researcher Madeleine van Oppen, of the Australian Institute of Marine Science, said the evolved microalgae was better at photosynthesis, which in turn improved the resistance of the coral animal.
"These exciting findings show that the microalgae and the coral are in direct communication with each other," Professor van Oppen said.
The next step will be to test the heat resistance of microalgae strains in adult colonies across a range of different species.
