Ex situ reproduction and recruitment of scleractinian coral Galaxea fascicularis

Sexual reproduction plays an important role in the population and community structure maintenance in scleractinian corals, particularly in growth and development after larvae settlement. Despite this, only few studies have been conducted to monitor the post-settlement growth and development of scleractinian coral larvae. This study aimed to obtain this data by collecting adult Galaxea fascicularis colonies from Weizhou Island coast (21°00′–21°10′ N, 109°00′–109°15′ E) and recording their complete life cycle, from fertilization to recruitment, for one year ex situ . The results demonstrated that G. fascicularis could reproduce sexually when reared in a tank for 2 y. Their embryo produced a “prawn chip” that lacked a blastocoel, indicating that G. fascicularis is a complex coral. Larvae evidently showed association with zooxanthellae four days after settlement and completed metamorphosis after 1 month. The mean diameter of G. fascicularis recruits was 4.74 ± 1.12 mm, and the survival rate was only 5.60% in the first year, which may be attributed to their competition with algae. To increase their survival rate without the interference of algae, we suggest that the recruits of G. fascicularis be reared ex situ to complete metamorphosis (1 month) and then transferred to the field. This study improved our understanding of the early life cycle of scleractinian corals.