Early-life history of three soft coral species in Okinawa, Japan

Larval development and subsequent settlement behaviour are important aspects which determine the persistence of sessile benthic organisms on shallow water tropical and subtropical coral reefs. However, only limited studies have been performed on the early-life histories of soft corals in Okinawa, Japan. In this study, we describe the development and settlement pattern of collected spawn materials from two <i>Sclerophytum</i> species and the larvae of a brooding <i>Heteroxenia</i> sp. from Okinawa Island, Japan. Results showed that for the brooding <i>Heteroxenia</i> sp., planulae can metamorphose and fuse at the pelagic stage, and have very low settlement rates on rubble substrates with crustose coralline algae (CCA). On the other hand, the planulae of the two <i>Sclerophytum</i> species have variable survival probability, but both mainly settle on rubble with CCA. These results highlight the differences in larval development and subsequent settlement behaviour and periods among soft coral species. This also serves as the first report describing the larval behaviour and settlement of these species in the subtropical region of Okinawa, Japan.