Coral Larval Rearing in Singapore: Observations on Spawning Timing, Larval Development and Settlement of Two Common Scleractinian Coral Species

— Small scale rearing of scleractinian coral larvae for experimental purposes has been practised for decades, but it is only in recent years that large scale larval rearing has been used as a means of providing corals for reef rehabilitation. This study aimed to develop optimal methods for rearing sexually propagated scleractinian corals from the broadcast spawning species Acropora hyacinthus and Pectinia lactuca in Singapore. Gravid A. hyacinthus was observed to spawn on the second to third day after full moon, while P. lactuca spawned on the fourth to sixth day after full moon. P. lactuca embryos displayed rapid development and the larvae settled within 48 h post-fertilization, with settlement peaks at 70 h and 118 h. A. hyacinthus propagules exhibited relatively slower embryonic development and later settlement, with the highest settlement rate at 142 h post-fertilization. Post-transplantation survivorship of the donor colonies for A. hyacinthus was 83% after 6 months and for P. lactuca, was 60% and 50% for colonies transplanted at Pulau Satumu and St. Johns Island, respectively.