Researchers find genes in algae that could stop coral bleach

Researchers have identified genes in algae that allow some corals to survive higher ocean temperatures without becoming bleached.

With the Great Barrier Reef and other important tropical reefs struggling to survive rising temperatures - while at the same time being damaged by our sunscreen - this is some much-needed good news for the coral ecosystems of the world.

Certain types of algae live inside corals as part of a symbiotic relationship that strengthen and protect both parties. Corals get their colouration from these algae, so when times are tough and corals are forced to kick out their algae tenants, they appear bleached.

Researchers from the University of New South Wales (UNSW) in Australia have found that algae growing in warmer temperatures could actually prevent corals from kicking them out, and this could protect them from bleaching as ocean temperatures rise.

The bright colour of tropical corals comes from a special type of algae, calledSymbiodinium, which feeds corals via photosynthesis, and corals give them a place to live in a return

"Tropical corals cannot survive without the Symbiodinium algae that live inside them. These tiny, photosynthetic organisms can provide the corals with more than 90 percent of their food," explains lead researcher Rachel Levin.

But when water temperature heats up past a certain point, the Symbiodiniumalgae freaks out and starts releasing toxins called reactive oxygen species. These toxins include nasty compounds such as peroxides, which damage both the algae and coral.

When this happens, the coral kicks the algae out to stem the damage, but in the process turns bone white, leaving itself starving and vulnerable to destruction. Its only hope for survival is the water temperature dropping so it can be recolonised by new algae.