Timing of coral (Swiftia exserta) spawning in U.S.G.S. Wetland and Aquatic Research Center, Gainesville, FL

The 2010 Deepwater Horizon oil spill injured mesophotic and deep-sea environments over a vast area. In order to restore the mesophotic and deep-sea coral species impacted by the spill, information on fundamental ecosystem processes such as reproduction is needed. During expeditions in 2021 and 2022, fragments of the mesophotic octocoral Swiftia exserta were collected from the northern Gulf of Mexico and transported to aquaria at federal facilities in South Carolina, Florida, and Texas. In the fall of 2021 and 2022, several of the fragments spawned in captivity, providing an opportunity to learn about their reproduction and inform future restoration activities. Broadcast spawning occurred on 19 and 20 October, 2021 and for 20 days from 29 September to 7 November, 2022. These spawning events permitted detailed observations of spawning behavior and timing, and colonies yielded over 2400 oocytes. Individual spawns were preceded by a distinctive “spawning posture” in the polyps, lasting between five minutes and two hours, and may have been cued by light. Swiftia exserta larvae settled and developed at comparable rates to other broadcast spawning octocorals, becoming swimming planulae by three days post spawn (dps) and starting to settle by 14 dps. These observations represent the first such records in S. exserta, and more broadly, a mesophotic coral in the Gulf of Mexico, providing important insights for the restoration of these species such as spawning season. Also, this investigation lays the foundation for future work to explore the influences of seasonal environmental variables, such as light and temperature, on spawning and reproductive seasonality in this species. This dataset contains the timing and dates of parent colonies with how many eggs they produced.