Stanford marine biologists have discovered stress-induced defensive genes in corals that serve as a predictor for damage caused by environmental pressure and climate change. The discovery could improve conservation strategies for at-risk reefs.

Stressful conditions lead coral cellular functions to fail, bleach and eventually die. Scientists predict rising ocean temperatures will increase coral bleaching worldwide. Before the discovery of the defensive genes, scientists were unable to predict coral bleaching.

Now, scientists can detect when corals are under stress: The defensive genes trigger a process to restore normal conditions within a cell, which is called the unfolded protein response.

Jane and Marshall Steel Jr. Professor in Marine Sciences and Director of the Hopkins Marine Station Stephen Palumbi, one of the authors on a paper detailing the discovery, said that the ancient defensive genes surfaced in response to high temperatures.

“For the first time, we are able to ask those corals, ‘how are you doing?’” Palumbi told Stanford News. “They don’t have a heartbeat. They don’t have a pulse. We need to know their vital signs in order to understand how they react to the environment.”

Palumbi worked with former Ph.D. student and current lecturer Lupita Ruiz-Jones ’16 to study over 17,000 coral genes belonging to three colonies in a lagoon on Ofu Island, American Samoa. For 17 days, Palumbi and Ruiz-Jones studied the corals’ response to stressful environmental conditions, such as high temperatures, oxygen and ocean acidity. Corals off of Ofu Island are particularly tolerant of unnaturally high ocean temperatures, making the reef an ideal spot for study.

Palumbi and Ruiz-Jones found that, when tides were low and temperatures were high, coral genes initiated the unfolded protein response. When tides and temperatures normalized, normal cellular function was restored.

“This response just shows how in sync corals are with their environment,” Ruiz-Jones told Stanford News.

Other mammals and yeast cells also initiate an unfolded protein response. Humans activate the same genes in response to diseases such as cancer.

The scientists’ discovery comes after the worst coral bleaching event the Great Barrier Reef has ever seen; climate change suggests that rising temperatures will cause even more coral bleaching in the future.

Scientists believe that exposing coral to high temperature environments may help prepare the organisms for this future. Understanding why some corals are so heat-tolerant could also help identify other coral colonies that withstand high temperatures.

“We know that corals have the ability to adapt and evolve to warmer water than we thought before,” Palumbi said. “We can use that as a primary asset to help them live through the next decades until we solve global climate change.”
Contact Gillian Brassil at gbrassil ‘at’ stanford.edu