Timing of reproduction in Montastraea annularis: relationship to environmental variables

The timing of reproduction was investigated in 15 colonies of Montastraea annularis located on the Port Royal Cays, Jamaica. Spawning occurred between Days 6 and 8 after August's and/or September's full moon. In the 14 wk prior to spawning, mean total gonad size increased from 0.30 plus or minus 0.17 to 34.38 plus or minus 13.20% of the polyp cross-sectional area. Gonad size was significantly correlated with temperature and light intensity, but was not correlated with photoperiod or rainfall. Spawning occurred in the month prior to the period of heaviest rainfall, when temperatures were at their maximum. A meta-analysis of spawning time and climatic conditions at 19 other geographical locations also showed that spawning occurs in those periods without heavy rainfall in which temperatures are warmest. The data presented here suggest that temperature is not the only environmental variable controlling the annual timing of coral spawning. Rather, the time of coral spawning is controlled by a combination of temperature and rainfall.