Seeking adaptation for corals in times of stress

Research at KAUST is providing insights into questions about coral bleaching, how it affects reef ecosystems and how it could be minimized.
© 2017 Anna Roik

The Red Sea, with high levels of salinity and exposure to some of the highest sea temperatures on Earth, provides an ideal base for exploring the potential impacts of global warming on fragile marine ecosystems. With a recent rise in the incidence of coral bleaching occurring on reefs around the world, KAUST researchers are contributing greatly to understanding the phenomenon and how to help corals survive in future.

“Coral bleaching is a complex phenomenon that occurs when corals get stressed,” said Professor Michael Berumen, who works in marine biology alongside Professor Carlos Duarte, Professor Christian Voolstra and their teams at the University’s Red Sea Research Center.

“Coral has a somewhat surprising stress response, which is to 'kick out' certain types of algae that live symbiotically within the coral tissue—although we don’t know exactly why it does this,” Berumen explains. “The algae give corals their colors, so you can see right through to the white skeleton of the coral animal when bleaching occurs, hence the term.”

Coral bleaching has the potential to reverse: algae may be able to return to the corals and help revive and replenish the reef. However, if certain stressors, such as high temperatures and fluctuating nitrogen levels, continue for an extended period, the corals cannot recover and eventually die.

Over the past two years, Scientists have become increasingly concerned for the future of these fragile yet vital ecosystems following wide-scale bleaching events of increased severity right across the globe.

“In a recent assessment, we estimated that 25-30% of all reefs in the Red Sea were bleached in late 2015,” said Voolstra. “My team study corals as metaorganisms—the coral animal, the algae symbionts and the bacteria that reside together interact and help each other in specific ways. The relationship is carefully balanced and offers significant benefits for the organisms involved.”

Read the full article