A probiotic saved heat-stressed coral for the first time

Scientists have revived heat-stressed coral using probiotic and post-biotic treatments in open water for the first time, according to a study published in Cell Reports. The team treated Acropora coral in the central Red Sea during a 2022 heatwave, when daily average seawater temperatures climbed as high as 89.5°F. Over 15 days, researchers isolated beneficial bacteria from healthy Red Sea corals and applied them to stressed colonies, tracking recovery by color and by the photosynthetic efficiency of the algae living inside. One probiotic and one post-biotic formula significantly improved coral health, even while the animals were still baking in the heatwave. Post-biotics are the inactivated version, which offer longer shelf life and easier transport. "When an innovative idea like this actually works, particularly under field conditions, we are positively surprised," said co-lead author Dr. Erika Santoro of KAUST University in Saudi Arabia. The post-biotic corals showed more Cobetia, a bacterium that helps them tolerate heat.