Reproductive seasonality of the reef building coral Platygyra Pini on Singapore's reefs

Abstract

The gametogenic cycle of Platygyra pini was investigated at three sites around Singapore's southern islands from Mar.2001 to Apr.2002. Equatorial locations, such as Singapore, typically experience moderate annual environmental variation. This has lead to the suggestion that the amplitude of environmental variation at the equator is insuffi cient to provide reliable cues to synchronise reproduction in marine invertebrates. However, distinct and predictable seasonal patterns of sea surface temperature and rainfall occur in Singapore as a result of the Southeast Asian Monsoon system. Platygyra pini had a seasonal pattern of gametogenesis, with maturation of gametes and spawning occurring predominantly in April. A second, smaller peak in reproductive activity occurred in November suggesting that some colonies also spawn at this time. The major spawning for this species followed a period of rising sea surface temperatures and occurred after the period of heaviest rainfall. While a correlation between environmental fl uctuations and spawning timing is not proof of a causal link, these data do indicate that the amplitude of change in environmental parameters such as temperature in Singapore is suffi cient to provide a seasonal cue for reproduction and spawning synchrony. © National University of Singapore.