MEPS 247:75-84 (2003)  -  doi:10.3354/meps247075

ABSTRACT: To determine the degree of variation in coral reproductive strategies at a low taxonomical level, we studied the planulae release pattern in 4 Madracis morphospecies, including 2 colourmorphs of 1 species. All species have the same basic planulae release strategy: colonies of all species release planulae from March to December and spawning intensity fluctuates highly at a daily scale. Two differences exist among species. Firstly, species differ in the number of planulae released, ranging between 0.02 and 0.11 planulae cm^-2 d^-1. Secondly, spawning is not related to a moon-phase for any species except for M. senaria. During the last quarter moon in November, M. senaria releases large numbers of planulae (n > 1000). Mass release of planulae concurrent with the Caribbean mass spawning has never been reported previously for a brooding coral species. For all species examined the number of planulae produced is related to yearly seawater temperature cycles with a lag period of 1 mo, i.e. planulae production at any given month is related to the seawater temperature of the preceding month. Yearly temperature cycles dominate over lunar cycles in the regulation of planulation in Madracis spp. The number of planulae produced is not related to colony size in any species. The brooding reproductive strategy can be divided into 2 sub-strategies: (1) organized mass release, or (2) gradual release in low numbers without any conspicuous pattern. Our data show that small but significant differences exist in the reproductive strategies of closely related coral species, even at the level of colourmorphs, which differ in the fraction of spawning colonies in a population.

KEY WORDS: Reproduction · Madracis · Planulae · Brooder · Coral · Caribbean · Life history