Aquaculture of the tropical sea cucumber, Stichopus monotuberculatus: Induced spawning, detailed records of gonadal and embryonic development, and improvements in larval breeding by digestive enzyme supply in diet

Abstract

Abstract Stichopus monotuberculatus is one of the most valuable tropical sea cucumbers, with high edible, medical and ecological values. In this study, the spawning of S. monotuberculatus was induced by a modified low-temperature stimulation method. Gonadal maturation, and embryonic, larval and juvenile development were described in detail, and larval breeding was improved by diets supplemented with multiple digestive enzymes. July-September resulted as the optimal breeding period of S. monotuberculatus in Hainan Province, China. Low-temperature stimulation was more suitable than traditional dry stimulation as a method for artificially inducing S. monotuberculatus spawning since its low mortality, whose fertilized eggs took approximately 21\xa0days to develop into juveniles. Compared to the control group, the diets with 2\xa0mg/L α-amylase, 2\xa0mg/L cellulase and 5\xa0μL/L trehalase added increased the larval survival rates at 6\xa0days by 21.37\xa0±\xa00.054%, 22.57\xa0±\xa00.088% and 29.83\xa0±\xa00.105%, respectively, and at 10\xa0days by 24.2\xa0±\xa00.094%, 30.02\xa0±\xa00.152% and 36.44\xa0±\xa00.052%, respectively. For the larval settlement rate, supplement of 1\xa0mg/L α-amylase, 1\xa0mg/L cellulase and 5\xa0μL/L trehalase in the diet could cause 5.30\xa0±\xa00.521-fold, 2.86\xa0±\xa00.521-fold and 4.66\xa0±\xa00.656-fold improvements relative to the control group, respectively. This study may contribute an advanced method for the large-scale artificial breeding and sustainable artificial culture of S. monotuberculatus.