The Reproductive Cycle and Spawning in a Caribbean Gorgonian

¹ Department Biological Sciences, SUNY at Buffalo, Buffalo, New York 14260

The reproductive biology of Plexuara A, a common but undescribed Caribbean gorgonian, was studied in the San Blas Islands, Panama. Oocytes were present in the polyps throughout the year, though a seasonal developmental cycle is evident. Early stage oocytes appeared at the base of the polyps in November. In January total egg volume per polyp began to increase and reached a maximum in early May. Total egg volume per polyp then decreased through the summer as mature eggs were released. Spawning occurred over a period of 4-7 days following each full moon in May, June, and July. Egg release was synchronous, starting at approximately 18:30 and lasting 90 minutes. Larval development is initiated just prior to or at the time of release. Initiation of larval development at the time of release without brooding is unknown for any gorgonian or scleractinian. Of 265 colonies examined from 6 reefs near San Blas Point, all but 3 contained gonads and were female. No male or hermaphroditic colonies have been found in the San Blas Point population. The scarcity or possible absence of males suggests that the eggs may develop parthenogenetically. Both of these unusual characteristics point to the need to use caution whenever the reproductive biology of a coral is described without an exhaustive examination of the complete reproductive cycle.