Coral bleaching and its effect on coral reproduction

What is coral bleaching?

Coral bleaching occurs when corals become stressed, usually due to prolonged exposure to warm water. Corals have a special relationship with small algae that live inside them called Symbiodiniaceae, which provide them with food and vibrant colors. When corals are under stress, they expel the Symbiodiniaceae causing the corals to turn pale or white. This is called coral bleaching. It's a significant problem because bleached corals are weaker and more vulnerable to disease, and if the stress continues, the corals can die.

How does coral bleaching affect coral reproduction?

Researchers studied the health of Acropora hyacinthus corals in Moorea five months after the 2019 mass bleaching event. They compared corals that had resisted bleaching with those that had bleached but then seemed to have recovered. Although both groups appeared healthy, the corals that had bleached and recovered had lower energy reserves and were less capable of reproducing.

This means that corals that recover from a bleaching event may be less able to produce new generations of corals compared to those that did not bleach at all.

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Leinbach et al. 2021