Pre-planular external development in the brooding coral Agaricia humilis

Abstract

In September 2003, translocation of the scleractinian coral Agaricia humilis on the reef of Curacao, Netherlands Antilles, was followed by a prodigious release of small floating premature larvae by all colonies (n = 19). Release occurred mainly during the first 3 d after sampling and peaked with 8.02 ± 7.60 (mean ± SD) embryos cm -2 d -1 on Day 2. These propagules developed externally into planulae and reached settlement competency about 3 d after release. During the whole 8 d monitor- ing period, the colonies also released normal planula larvae (0.27 ± 0.39 cm -2 ), which were able to settle without delay. We assume that premature release occurred as a result of stress connected with the sampling method applied. The obligatory development of at least 3 d has important conse- quences for dispersal. This is one of the first reports of successful external development of embryos into planulae in a coral species, known as a brooder, and demonstrates yet another possible mode of reproduction in scleractinian corals.