Endozoicomonas bacteria boost coral heat survival, researchers report. The finding comes from a new study by NYU Abu Dhabi that examined Acropora pharaonis corals from the Arabian Gulf, including samples collected near Saadiyat Island.
Bacterial Hormone Production Under Heat Stress
The research, published in Nature Microbiology, shows that the Endozoicomonas group begins synthesising steroid hormones such as testosterone and progesterone when water temperatures rise. These hormones, traditionally linked to complex organisms, appear to act as immune‑modulating signals for the coral host. By supplying the missing hormones, the bacteria enable the coral to sustain a more effective defensive response as heat stress intensifies.
"When temperatures become high, corals lose some of their ability to produce steroid hormones that are important for regulating their immune system,"— Amin Mohamed, Research Associate, NYU Abu Dhabi
Implications for Coral Immunity
According to the study, the hormone boost translates into a stronger immune reaction that protects coral cells from damage. The authors describe this as a previously unknown function of the coral microbiome, highlighting that the bacterial partners do more than simply coexist with their hosts. "These bacteria are doing much more than simply living alongside the coral,"— Shady Amin, Associate Professor of Biology, NYU Abu Dhabi adds, noting that the microbes supply molecules essential for immune regulation during stressful periods.
The work was carried out through NYU Abu Dhabi’s Center for Genomics and Systems Biology, in collaboration with John Burt and the Marine Microbiomics Lab. By focusing on the microbial component of reef health, the study opens a new avenue for scientific inquiry that complements existing restoration methods such as coral nurseries and assisted evolution.
Potential Conservation Strategies
While traditional coral‑conservation tactics target the coral itself, the authors suggest that harnessing beneficial microorganisms could become a complementary strategy. As ocean temperatures continue to climb, leveraging the natural hormone‑producing capacity of Endozoicomonas may help reefs retain resilience without extensive human intervention. The authors caution that further field trials are needed to translate laboratory insights into practical applications, but they view the discovery as a promising step toward more holistic reef management.