Coral Spawning Triggered by Late Summer Full Moons

Visit the Florida Keys on a Late Summer Full Moon Night to Witness the Annual Coral Spawning

A full moon night in August or September may provide an exciting opportunity for divers and snorkelers in the Florida Keys to witness an incredible annual phenomenon on the coral reefs. Boulder and branching corals such as brain, star, elkhorn, and staghorn corals release millions of gametes into the tropical waters in the wondrous annual ritual that is coral spawning.

The exact conditions that trigger the event are still unclear but scientific observations have shown that along with water temperature, tidal, and light cycles, there is a strong connection between coral spawning and seasonal lunar cycles.

In order to guarantee their survival, each year, in a spectacular synchronized event the coral animals all over the reefs release a wondrous white excretion that is the exchange of gametes (eggs and sperm) to maximize the chances of fertilization. This universal release over a very broad area means there will be so many fertilized eggs that hungry predators are overwhelmed and can’t possibly eat them all.

After fertilization, the larvae or planula rise to the surface to drift on the current for days or even weeks before settling to the bottom where they grow into a polyp. As the polyps grow a colony is formed and the calcareous secretions create what we know as a coral reef.

There is no absolute certainty but, this year there will be a full moon on Wednesday, Aug. 1,  Friday, Aug. 31, and Saturday, Sept. 29. Many Keys dive operations will be offering coral spawning trips and who wouldn’t enjoy a moonlight dive on a coral reef in the Keys?

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