Scientists have discovered that specific bacteria living within coral colonies can produce hormones to help the organisms survive extreme heat. This mechanism, identified in a recent study, offers a potential new strategy to mitigate coral bleaching as global ocean temperatures continue to rise.
The microbiome
Researchers studying coral in the Persian Gulf found that certain colonies remained healthy during heat waves. Amin Mohamed, a researcher at NYU Abu Dhabi and lead author of the study, said that the difference appeared to be linked to the coral’s microbiome.
“We found other colonies that remained healthy — with no sign of disease whatsoever — at the same temperature,” Mohamed told me. “So this got us very interested in understanding what is behind the mechanisms keeping these [corals] healthy and stable.”
The team discovered that healthy corals maintained a population of Endozoicomonas bacteria. These bacteria produce the hormones testosterone and progesterone, which help regulate the coral’s immune system during periods of high temperature.
Microbiologists React to Bacterial Function Under Temperature Stress
The study has drawn interest from experts in coral microbiology for its specific focus on bacterial function under temperature stress.
“It’s a really exciting and interesting study,” said Rebecca Vega Thurber, a coral microbiologist and Director of the Marine Science Institute at the University of California, Santa Barbara.
“There’s been a lot of hypotheses about what the bacterial components of the coral are actually doing, and actually demonstrating it is a really important step forward. I also really like this study’s connection to temperature stress, which is the most important stressor for coral reefs right now.”
Despite the potential for these findings, experts caution that applying such mechanisms in the wild remains complex. Vega Thurber warned that suppressing the immune response during heat waves opens corals up to the possibility of being more easily infected by opportunistic bacteria.
Research efforts
The research follows a broader effort to address the fourth global coral bleaching event, which impacted 84 percent of the world’s coral reef area between 2023 and 2025. Scientists at organizations including the Australian Institute of Marine Science (AIMS) and Victoria University are exploring various forms of assisted evolution, such as breeding heat-tolerant corals and introducing beneficial algae like Durusdinium.
Madeleine van Oppen, a senior principal research scientist at AIMS, emphasized that the next phase of this research must focus on real-world application.