Studies On Breeding And Genetic Variation Of The White Sea Cucumber Apostichopus Japonicus

1. Effects of salinity, temperature and stocking density on larval growth andsurvival of the white race Apostichopus japonicusFor large-scale seed production of the white race A. japonicus, it is necessary toinvestigate survival and growth of larvae under different environmental parameters.The present study was designed to compare the larval survival and growth of thewhite and ordinary A. japonicus under different salinities (25,29,33,37‰),temperatures (19,21,24,27℃) and stocking densities (0.1,0.2,0.4,0.6ind/mL), inorder to identify the optimal rearing factors. Based on the results of this study, asalinity of25‰is the optimal rearing condition, lower survival and growth valueswere obtained at a higher salinity of37‰. Higher survival and growth values wereobtained for both the white and ordinary A. japonicus at a temperature of19℃. Andhigher survival and growth values were obtained for the white A. japonicus at astocking density of0.6larvae/mL. Therefore, a salinity of25‰, a temperature of19℃and a stocking density of0.6larvae/mL are considered optimal for early growthof the white A. japonicus.2. The effects of salinity and temperature on the growth and survival rates ofwhite Apostichopus japonicus juvenilesThe growth and survival of white and ordinary A. japonicus juveniles wasmeasured in different environmental conditions (15,20,25℃combined with23,27,31,35‰). Thirty individuals were used in each combined condition. The resultsshowed that the white sea cucumber juveniles have higher survival at temperatures of15-20°C and salinities of27-31‰. The best growth was obtained at20°C and allsalinity levels, indicating that the growth of white sea cucumber juveniles was mainlyaffected by the temperature. Survival and growth coincide best at around20°C and 27-31‰. The results demonstrated the optimum conditions for production of whitesea cucumber juveniles. The information obtained in this study will be valuable forthe development of sea cucumber aquaculture industry.3. AFLP analysis of the white Apostichopus japonicusThe amplified fragment length polymorphism (AFLP) technology is a new typeof molecular markers, has good stability, high repeatability, fast detection. Also it isefficient and predictable without genome sequence information and easy to automateanalysis. In this study, AFLP was used to analyze the genetic diversities in white andordinary A. japonicus populations. The result indicates that using13pair of selectiveprimers185AFLP loci are analysed in the two populations. The percentage ofpolymorphic loci is73.03%for white A. japonicus, and89.33%for ordinary A.japonicus. The gene diversity in the white and ordinary A. japonicus populations is0.40and0.41, respectively. By the pairwise comparion between the two populations,high level of genetic differentiation is found within population, but not betweenpopulations.