Microalgae study raises hopes of cure for bleaching that kills coral

Scientists have found a way to make coral resistant to the impact of increasingly warm waters that has led to the destruction of about half of the Great Barrier Reef.
Researchers focused their efforts on the microalgae that live in the tissues of corals, which are expelled when sea temperatures rise due to climate change, turning the coral completely white, a phenomenon known as coral bleaching.

The team removed the microalgae, grew new strains and exposed them to warmer temperatures of about 31C for four years.

Image: The Great Barrier Reef lost half its coral in summer heat waves in 2016 and 2017

Image: Major bleaching has affected the coral reefs of the Society Islands in French Polynesia
They found all 10 heat-evolved strains showed increased tolerance to the elevated temperature, and believe their findings may help in the effort to restore coral reefs, which are being killed off by marine heatwaves.
The scientists then injected coral larvae with one strain each and exposed them to 31C (88F) heat for a week and found three of the 10 strains protected the coral from bleaching.

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While evidence suggests corals are gradually adapting to a warmer world, scientists say the species are struggling to keep pace with climate change.

The world’s largest reef, Great Barrier Reef, lost around half of its coral to bleaching events in summer heatwaves in 2016 and 2017.

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Lead author Dr Patrick Buerger, of CSIRO, which is Australia’s national science agency, said: “Coral reefs are in decline worldwide.
“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.
“Our novel approach strengthens the heat resistance of coral by manipulating its microalgae, which is a key factor in the coral’s heat tolerance.”

Image: A healthy, multi-coloured coral reef
Professor Madeleine van Oppen, of the University of Melbourne and the Australian Institute of Marine Science (AIMS), added: “We found that the heat tolerant microalgae are better at photosynthesis and improve the heat response of the coral animal.
“These exciting findings show that the microalgae and the coral are in direct communication with each other.”
The researchers are now planning to test the strains across a wider range of coral species.

Source : Sky News