FLORIDA KEYS — Divers and snorkelers have an opportunity to witness a fascinating annual phenomenon among coral reefs as boulder and branching corals release millions of gametes in synchronized mass-spawning rituals.

Sparked by the August and September full moons, the rare and wondrous underwater exchange of gametes (eggs and sperm) means the continued survival of coral reefs including brain and star corals and the protected elkhorn and staghorn corals. 

The spectacular white excretion enables the eggs and sperm to enter the water in massive quantities over a broad geographic area, maximizing the chances of fertilization and overwhelming predators with more food than they can consume. 

When egg and sperm unite, the newly formed larvae, or planula, ascends to the surface to float in the current. Within a matter of days or even weeks, the planula settles to the bottom to grow into a polyp and eventually form colonies. 

What triggers this event remains unclear, though scientific observations indicate a strong connection between the coral spawn and seasonal lunar cycles as well as multiple environmental cues such as water temperature, tidal and 24-hour light cycles.  

Cultured corals, the result of ongoing wild transplant efforts by Key Largo’s Coral Restoration Foundation, also have been documented as spawning.

Though the polyp release cannot be guaranteed to happen on the exact date, the 2012 late summer full moons fall on Wednesday, Aug. 1; Friday, Aug. 31, and Saturday, Sept. 29. 

Divers can inquire with Keys dive operators about joining scheduled coral spawning night dives around those dates.

Florida Keys diving: www.fla-keys.com/diving

Florida Keys visitor information: www.fla-keys.com or 1-800-FLA-KEYS 

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