One of nature's most fascinating symbiotic arrangement between corals and algae, which led to the formation of the Great Barrier Reef in Australia, is facing grave threats from climate change.
According to a report from the ARC Centre of Excellence for Coral Reef Studies, the symbiosis between coral and zooxanthellae, tiny one-celled plants, underpins the economies and living standards of many tropical nations and societies who harvest their food from the reefs or have developing tourism industries. The issue of whether the partnership is robust enough to withstand the challenges of climate change is driving a worldwide scientific effort to decipher how corals and their symbiotic algae communicate with one another," said Professor David Yellowlees of the ARC Centre of Excellence for Coral Reef Studies (CoECRS) and James Cook University.
"It's an incredibly intricate relationship in which the corals feed the algae and try to control their diet, and the algae in turn use sunlight to produce "junk food" - carbohydrates and fats - for the corals to consume," he added.
But, where it all breaks down is when heated water lingers over the reef and the corals expel the algae and then begin to slowly starve to death. This is the bleaching phenomenon Australians are by now so familiar with, and which is a feature of global warming.
Now, researchers in the Centre of Excellence are trying to understand the chemical and genetic basis for the conversation that goes on between a coral and its particular algae, and to establish whether, if it loses its algae in a bleaching event, it can establish the same relationship with a different strain of algae.
The challenge for scientists is to understand the 'chemical conversation' that goes on between the corals and zooxanthellae, the genes which control it - and to explore whether corals which lose their primary partners can survive using other algae or must inevitably die.
"In other words, how robust this symbiotic system is and whether it can withstand shocks from warming, ocean acidification, changes in sunlight levels and other likely impacts from human activity," the researchers said.
"The bottom line here is the survival of the Great Barrier Reef and coral reefs the world over," they added.
Corals have been wiped out five times in the Earth's history, suggesting they are highly vulnerable to changes in ocean conditions.