Could heat-tolerant algae save coral reefs from climate change?

Scientists have developed heat-developed algae in a breakthrough that could help save endangered coral reeds. 

The development has been revealed just months after Australia saw its third mass bleaching event in five years, amid record-high ocean temperatures at the Great Barrier Reef, as The Guardian reported at the time. 

Coral bleaching occurs when rising sea temperatures cause corals to expel the colourful Symbiodiniaceae microalgae that live in their tissues and supply them with nutrients. As the algae is expelled, the corals lose their colour and starve to death.

But scientists at Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) have discovered that coral reefs could survive if the heat tolerance of their resident algae was raised, reports New Scientist. 

Researchers from the national science agency and the University of Melbourne heated Symbiodiniaceae algae to 31°C in a laboratory for four years to train the organism to tolerate higher water temperatures. Over time, the algae evolved genetic changes that mean it could have greater heat resistance.

The researchers then took coral larvae from the Great Barrier Reef and mixed it with either standard algae or the heat-resistant algae before heating both blends to 31°C for one week. The coral with the “non-trained” algae quickly bleached, but the coral with the heat-resistant algae remained healthy.

Madeleine van Oppen of Melbourne University told The Times: “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. We’re putting all our efforts into this now in case we need it to have it ready as an intervention in the future.”

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