Scientists can tell how some corals survive climate-related coral bleaching events

Increasing ocean temperatures due to climate warming are putting the world's coral reefs at risk of bleaching, a devastating process by where once vibrant and colourful corals become a ghostly, skeletal white.

Now scientists in Hawaii and Michigan think they know why some corals are susceptible to bleaching and others are not.

Canadian scientist Robert Quinn, an assistant professor of microbiology at Michigan State University, spoke with Quirks & Quarks host Bob McDonald about what might be driving that crucial difference in how corals respond to the heat.

Back in 2015, an extreme heating event that led to the bleaching of corals around the world created an opportunity for Quinn and his colleagues to study why some corals — even of the same species — turn white and others don't.

The researchers studied corals that hadn't apparently been affected by the 2015 event, and compared them to some that had been bleached, but recovered. In particular they were looking for differences in the underlying biochemistry of the algae living symbiotically with the corals.

The biggest difference turned out to be a type fat-related molecule, known as betaine lipids that form membranes around the algae and its internal photosynthetic machinery.

Corals that managed to withstand the heat and retained its vibrant hue contained more saturated lipids, compared to the previously bleached corals that contained more unsaturated lipids.

Saturated lipids tend to be more rigid, which is why margarine, which is made of saturated oil, is a solid and unsaturated oil is liquid.

Quinn suspects that rigidness may be giving the algae's membranes more support to withstand heat.

They hope that by identifying which coral algae contain these saturated lipids, they could better help restoration efforts by selecting coral that may be resistant to bleaching.

• Research paper in the journal Nature Ecology & Evolution

Produced and written by Sonya Buyting