Assessing the reproductive potential and development of the tropical short-spined white sea urchin, Salmacis sphaeroides (Linnaeus, 1758)

Abstract

ABSTRACT Previous studies have achieved success in obtaining cultured juveniles of the sea urchin Salmacis sphaeroides, but few have reported their reproduction potential and development rates. This comprehensive study examined the spawning potential of broodstock and described embryonic, larval and juvenile development. The broodstock consisted of wild-caught specimens from Singapore’s coastal waters that were regularly provided a mixed animal-plant diet comprising 3 g prawn and 3 g corn. Gametes were obtained using 0.5 M of potassium chloride (KCl) injection into the coelomic cavity. Fertilization rates of the 32 spawning attempts varied from 42.9% to 100%. Hatched larvae were subsequently reared with a density of 0.5 larvae ml−1 in 50 µm filtered seawater at 28°C and fed 20,000 cells ml−1 of Tisochrysis lutea once every 2 days. Despite the presence of natural biofilms as settlement cues, the settlement rates in culture were very low and variable (2.08–9.78%). The majority of juvenile S. sphaeroides from F1 and F2 generations was sexually mature at ≥35 mm in test diameter, and the sex ratios were female-biased, ranging from 1:1.14 to 1:8. Findings from this study open up new opportunities for developing tropical sea urchin cultures under controlled rearing systems that can guarantee production.