Many corals reproduce by releasing millions of eggs and sperm into the water in coordinated events. What better way to ensure you’ll find a mate than triggering a mass orgy? The coral gametes are positively buoyant and collect at the water surface, where fertilization takes place. Within a few days the fertilized eggs develop into what are called planula larvae, a small sausage shaped stage of the coral which has the sole task of finding and settling on a suitable location where the coral colony will spend the rest of its life.
For public aquariums interested in displaying corals in captivity, spawning events are a big deal. The collection of millions of potential coral fragments can be accomplished in a sustainable way with no damage to the existing coral colonies. An initiative of public aquariums and coral reef scientists called SECORE (SExual COral REproduction) collects gametes from spawning events and carefully holds them until they are fertilized and ready to settle in captivity. SECORE’s tireless work in the Caribbean has resulted in thousands of captively grown fragments of the critically endangered stony coral Acropora palmata.
On the second day of the Philippine expedition Steinhart staff collected several hundred egg and sperm bundles from two yet-to-be-identified spawning Acropora spp. Tending to the fertilized eggs is a delicate task, but we hope to have fantastic news of settlement in the next few days.
During the Hearst Expedition, biologist from the California Academy of Sciences witnessed Acropora spspawning (video below). They collected the spawn and are attempting to get it to settle while in the field.