Seasonality and lunar periodicity in the reproduction of Pocilloporid corals

Reproductive seasonality and lunar periodicity of planula release were investigated for the three brooding corals Pocillopora damicornis, Seriatopora hystrix, and Stylophora pistillata at Heron Island in the southern Great Barrier Reef. Branch fragments collected from undisturbed colonies in the field were used to determine when planulae were present for all three species, and direct observations of planula release were made on colonies of Pocillopora kept in aquaria. All three species displayed marked seasonal variation in reproductive output, with nearly all reproductive activity occurring over the summer months. Pocillopora exhibited distinct lunar periodicity in planulation, with planula release occurring around three quarter moon, and no planulae being present in samples collected between new and full moons. Seriatopora also displayed lunar periodicity of planula release, although it was not as distinct as for Pocillopora, while Stylophora did not show any lunar periodicity.