Résumé
This study provides the first detailed quantitative data on the sexual reproduction, larval development and settlement competency periods of broadcast spawning Acropora reef corals at Moorea, French Polynesia. From 2002 to 2004 the timing and mode of sexual reproduction for Acropora reef corals was examined at four sites on the outer reef slope and reef lagoon. To determine extent of spawning synchrony within and among species, colonies of Acropora spp. were tagged and repeatedly sampled, or collected for spawning in flow through outdoor aquaria, during September through November. Spawning was observed in aquaria and inferred in the field from the disappearance of mature gametes for 13 species of Acropora, between 6-9 nights after the full moon in September, October and November. Following spawning in November 2004, post fertilisation samples were taken from A. nasuta, A. striata and A. lutkeni to compare the morphological stages of embryo and larval development from early cleavage to ciliated planula larvae. Larval development and settlement competency periods were studied using A. retusa and A. striata planulae. Larval attachment onto settlement tiles occurred within 3-4 DAS (days after spawning) in both species. Peak periods of larval metamorphosis and permanent settlement occurred between 4-10 DAS for A. retusa and 5-10 DAS for A. striata. The early development and initial rapid attachment patterns of A. retusa and A. striata larvae indicate that some planulae may be retained close to their natal reef. However, the extended settlement competency periods observed in A. striata (31 DAS) and A. retusa (26 DAS) suggest that some planulae also have the potential for dispersal away from their natal reef before settling. This information is important for understanding and predicting the likely sources of larval supply to Moorea, and examining the potential likelihood of reef interconnectivity via larval dispersal in French Polynesia