Aussie scientists ‘heat-proof’ coral
Inoculating coral with microalgae that have been deliberately evolved to tolerate high temperatures might restore health in bleached corals.
Most of the hard corals that form the Great Barrier Reef rely on a symbiotic relationship with tiny algae called zooxanthellae. The coral provides these microalgae with a structural home and nutrients. In turn, the microalgae give coral energy. But when water temperatures get too warm, this relationship breaks down and the coral expels the microalgae. The coral loses its colour, appears bleached, starves, and is left susceptible to diseases and eventually death.
Now researchers at the University of Melbourne and Australian Institute of Marine Science have enhanced a microalgal species – Cladocopium proliferum – to withstand warmer water temperatures through lab-based “assisted evolution”. The researchers bolstered the microalgae’s heat tolerance through exposure to elevated temperatures over 10 years. They then offered these evolved microalgae to a series of chemically bleached adult coral fragments from the species
Galaxea fascicularis. The heat-evolved microalgae maintained symbiosis with the coral for two years, promoting a faster recovery from bleaching and enhancing the coral’s heat tolerance.