Early Development and Juvenile Culture of Parathyone braziliensis (Dendrochirotida: Cucumariidae), a Rapidly Developing Tropical Sea Cucumber with Aquaculture Potential

Abstract

Sea cucumbers are ecologically important marine invertebrates that play key roles in nutrient recycling and are highly valued in Asian gastronomy, traditional medicine, and as a source of bioactive compounds. Increasing market demand has led to severe impacts on natural populations through overfishing and illegal harvesting. Aquaculture has been proposed as a sustainable alternative, with hatchery breeding and juvenile production representing critical steps for successful cultivation. This study provides the first report of spawning induction, early development, and experimental juvenile culture of Parathyone braziliensis, an endemic species from Brazilian coast. Broodstock were collected at Armação do Itapocoroy (southern Brazil), transferred to a hatchery and successfully induced to spawn through thermal stimulation. Approximately 1 h after thermal shock, males released sperm, followed by the females releasing large, negatively buoyant oocytes (458.1 ± 27.9 µm). After fertilization, development was lecithotrophic and occurred entirely within the fertilization envelope, with no planktotrophic auricularia stage. The pentactula stage (458.3 ± 41.9 µm) was reached after approximately 60 h. Early juveniles (835.5 ± 148.2 µm) were observed after 8 days, and individuals reached 2.51 ± 0.2 mm after 36 days, when they were transferred to a sea-based nursery system. After 4 mo of nursery rearing, juveniles reached a mean length of 20.81 ± 4.2 mm, with survival of 92.8%. The absence of a planktotrophic larval phase represents a significant advantage for hatchery production, as it eliminates one of the most labor-intensive and mortality-prone stage of sea cucumber culture. High juvenile survival and rapid growth observed in the sea-based nursery further highlight P. braziliensis as a potential candidate for sea cucumber aquaculture development in Brazil.