Larval settlement patterns, dispersal potential, and the effect of temperature on settlement rates of larvae of the broadcast spawning reef coral, Platygyra daedalea, from the Great Barrier Reef

This study examined the initial larval settlement pattern, the settlement-competency period, and the effect of temperature on settlement rates of larvae of the broadcast spawning reef coral, Platygyra daedalea, from the Great Barrier Reef. Approximately 19% of larvae attached to settlement substrata 3-4 days after spawning (DAS), prior to complete larval metamorphosis and permanent settlement, which began at 4-6 DAS. This early larval attachment behaviour could enhance the retention of some P. daedalea larvae on, or near, their natal reefs, thereby allowing some degree of self-seeding of local populations. In contrast, the maximum larval settlement-competency period was 93-105 DAS, with the peak period of larval settlement occurring at 36-42 DAS and 33-41 DAS in repeated experiments over two years. The delayed period of peak settlement and the extended competency periods of these larvae indicate that there is considerable potential for meso-scale and long-distance dispersal of some P. daedalea larvae. Slightly elevated temperatures enhanced the development and settlement rates of P. daedalea larvae, which suggests that seawater temperature may be an important factor influencing patterns of coral larval settlement on coral reefs.