Probiotics prevented coral bleaching during a Red Sea heat wave: Study

During a 2022 heat wave off Saudi Arabia, corals treated with probiotic bacteria kept their color and photosynthetic function while untreated corals in the same reef declined, according to a study led by KAUST microbial ecologist Raquel Peixoto. The team administered bacteria isolated from healthy corals, plus heat-killed 'postbiotic' versions, directly into the water near test corals over 15 dives across 15 days.

Genetic sequencing showed the treatments altered the corals' microbiomes, including boosting a bacteria genus thought to aid heat resistance. An outside marine scientist called the field result, as opposed to prior tank experiments, 'fantastic,' while noting a longer study is needed to confirm the treatments improve actual coral growth and survival.

The researchers acknowledge real limits: only one coral species was tested, treatment is labor-intensive, and reefs cover far more area than syringes can practically reach. They are now developing slow-release gel beads to scale the approach, though they don't yet know how long the beads keep the bacteria alive.

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