Planulation, larval biology, and early growth of the deep-sea soft corals Gersemia fruticosa and Duva florida (Octocorallia: Alcyonacea)

Abstract

. Although the reproductive biology and early life-history stages of deep-sea corals are poorly understood, such data are crucial for their conservation and management. Here, we describe the timing of larval release, planula behavior, metamorphosis, settlement, and early juvenile growth of two species of deep-sea soft corals from the northwest Atlantic. Live colonies of Gersemia fruticosa maintained under flow-through laboratory conditions released 79 planulae (1.5–2.5 mm long) between April and early June 2007. Peak planulation in G. fruticosa coincided with peaks in the chlorophyll concentration and deposition rates of planktic matter. Metamorphosis and settlement occurred 3–70 d post-release. The eight primary mesenteries typically appeared within 24 h, and primary polyps grew to a height of ∼6–10 mm and a stalk diameter of ∼1 mm within 2–3 months. Planulae of Duva florida (1.5–2.5 mm long) were extracted surgically from several colonies and were successfully reared in culture. Primary polyps reached a height of ∼3–4 mm within 2–3 months. No budding of primary polyps was observed in either species over 11–13 months of monitoring, suggesting a very slow growth rate.