Early life history of the cold-water coral Desmophyllum dianthus (Scleractinia) revealed through ex situ observations

Abstract Cold-water coral reproduction remains poorly documented because most of these species inhabit deep environments that limit direct observation. In Northern Chilean Patagonia, environmental conditions resembling deep habitats allow the cold-water scleractinian Desmophyllum dianthus to occur at unusually shallow depths, making direct collection possible by SCUBA diving. Corals were collected during May–July 2022–2024 from Yerbas Buenas in the Gulf of Ancud and from two locations in Comau Fjord. Live specimens were transported to laboratory facilities to document reproductive activity (spawning, embryogenesis and early larval behaviour) throughout the July–August spawning season. Desmophyllum dianthus exhibited broadcast spawning, with multiple gamete-release events per polyp within a single reproductive season. Male and female spawning behaviours differed consistently. Embryonic development progressed rapidly, reaching early cleavage stages at around 4 h, and the planula stage at approximately 44 h. Larvae swam actively and showed evidence of feeding at 15–25 days post-fertilisation. Early settlement behaviour occurred as early as 9–10 days, indicating a relatively short pre-competency period for a spawning cold-water coral species. These findings reveal species-specific reproductive traits that may reflect adaptations to the constraints of achieving synchrony with conspecifics in the deep sea and establish a baseline for understanding the reproductive ecology of this cold-water coral species.