Opportunistic observations of reproductive mode, larval settlement and development of a New Zealand deep-sea stony coral, Goniocorella dumosa

Little is known of the reproductive traits and dispersal potential of many deep-sea corals, and in-aquarium spawning has been observed for very few species globally. Here, we document the first known observation of larval release by Goniocorella dumosa (Alcock 1902), a habitat-forming deep-sea scleractinian stony coral found in the New Zealand region. In contrast to previous understanding that G . dumosa were broadcast spawners, colonies of G . dumosa released large (approx. 1.1 mm × 0.8 mm) free-swimming planula larvae. Further investigation confirmed that this species is a brooder, with up to 10 mature larvae found in single mature polyps, and is the only known brooding deep-sea scleractinian branching coral that produces swimming larvae. Mature corals were collected from the Chatham Rise (400 m depth, 43º 22.13 S, 179° 27.09 E), to the east of New Zealand, in June 2020. We describe the observed larval behaviour, settlement and post-larval growth and development of G . dumosa , held in an aquarium, from September to December 2020. The more limited dispersal potential for larvae from a brooding species compared to a broadcast spawning coral has significant implications for both population connectivity and for the potential recovery of this species from disturbance by human activities. This in turn could influence management and protection strategies for G. dumosa and their habitat.