SYNCHRONOUS PLANULATION OF MANICINA-AREOLATA (SCLERACTINIA) WITH LUNAR PERIODICITY

Field observations and histology were used to examine the reproductive ecology of the scleractinian coral Manicina areolata (Linneaus) from the San Blas Islands, Panama. M areolata is a simultaneous hermaphrodite with brooded larvae. Planulation is synchronous and closely correlated with lunar phase, with most planulae released within 2 d of the new moon. In contrast to other brooding species, a short breeding season peaks during June and July. Colonies are not reproductive until they have reached a height of 1.5 to 2.0 cm, after 2 to 3 yr of growth. Planula production in mature colonies is on the order of hundreds to thousands of larvae per colony per year. Fecundity is not related to size after colonies become reproductive. Distribution of planula production is strongly skewed to the right, with 5 % of the colonies producing over 30 % of the larvae. These highly fecund colonies are not morphologically different from other colonies, and most likely represent annual or small-scale spatial variation (meters in extent) in reproductive effort or fertilization success. Studies of reproductive output in scleractinian corals must be adequately designed to account for such fine-scale variation, since analyses based on a few colonies may be inappropriate for estimating population larval production.