Direct evidence of sexual reproduction in the zebra coral, Oulastrea crispata (Anthozoa, Scleractinia), in Japan

Reproductive traits of scleractinian corals are important in understanding their ecology and for maintaining coral populations; however, it has been reported for no more than 30% of species. Oulastrea crispata (Lamark, 1816) has the greatest north-south distribution in the Indo-West Pacific. This species is also known as one of the most stress-tolerant corals. Thus, most previous studies on O. crispata have examined its physiological, ecological, morphological, or genetic traits and its symbiotic dinoflagellates relative to its broad distribution and its stress tolerance. However, there have been few studies on its reproduction. In this study, the release of sperm and eggs of O. crispata was observed under laboratory rearing conditions in Shirahama, Kii Peninsula, Japan. This is the first direct evidence of sexual reproduction in this species, and the contribution of sexual reproduction to Oulastrea biology is briefly discussed.