As a consequence of climate change, coral reefs are increasingly affected by bleaching events. Coral reefs are formed by groups of coral polyps. The reefs provide natural habitats for marine animals such as fish. They also act as buffers for coastlines during storms.
Rising water temperatures are stressful for corals, causing them to lose their symbiotic algae. The corals not only turn pale but, importantly, they lose a major source of nutrients and are more susceptible to illness and death. The fourth global bleaching event is currently in progress.
The U.S. National Oceanic and Atmospheric Administration (NOAA) states that coral bleaching is becoming more frequent and severe [1]. Experts have observed extremely high ocean temperatures in the past year, as well as major coral death around Florida and the Caribbean. Scientists are currently seeking ways to protect these important ecosystems.
Raquel S. Peixoto, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia, and colleagues are searching for an approach to make corals more resistant to the negative effects of climate change [2]. Their research focuses on reshaping the coral microbiome, i.e., the entirety of microorganisms living on the coral surface. The microbiome of healthy corals contains beneficial microorganisms, so-called probiotics, that protect corals, e.g., by defending them against pathogens or degrading toxic compounds.
The team inoculated corals in the central Red Sea with a mixture of selected probiotics over a period of three months. This treatment did, in fact, reshape the coral microbiome. Some of the microorganisms used were significantly enriched in the treated corals, and the researchers also observed an increase in other beneficial groups and a decrease in potential pathogens. The probiotic strains were, however, not detected long-term after the treatment at high abundance. The researchers propose that repeated and continuous inoculations may be required in some cases. They found no off-target effects on the surrounding microbiomes in the seawater and sediment.
References
- [1] NOAA confirms 4th global coral bleaching event,
National Oceanic and Atmospheric Administration,
noaa.gov 2024. - [2] Probiotics reshape the coral microbiome in situ without detectable off-target effects in the surrounding environment,
Nathalia Delgadillo-Ordoñez,, Neus Garcias-Bonet, Inês Raimundo, Francisca C. García, Helena Villela, Eslam O. Osman, Erika P. Santoro, Joao Curdia, Joao G. D. Rosado, Pedro Cardoso, Ahmed Alsaggaf, Adam Barno, Chakkiath Paul Antony, Carolina Bocanegra, Michael L. Berumen, Christian R. Voolstra, Francesca Benzoni, Susana Carvalho, Raquel S. Peixoto,
Commun. Biol. 2024.
https://doi.org/10.1038/s42003-024-06135-3
