盐化幅度、速度及方式对凡纳滨对虾仔虾生长和存活率的影响

本研究测定了盐化幅度(3/d、6/d、9/d、12/d和15/d)、盐化速度(1、3、6、12和18 h/次)和盐化方式(前期盐化、中期盐化、后期盐化和间隔盐化)与凡纳滨对虾(Litopenaeus vannamei)仔虾生长发育、活力和存活率的关系。研究结果显示，不同盐化幅度、盐化速度和盐化方式均显著影响盐化标粗过程中仔虾的生长发育、活力和存活率(P<0.05)。综合考虑生长性能、苗种活力和存活率等因素，最适盐化幅度为3~6/d，在该盐化幅度范围内，仔虾存活率可达74.07%~78.83%；盐化幅度超过9/d时，仔虾存活率显著下降(P<0.05)，其中，盐化幅度达到15/d时，存活率仅为43.37%。过快的盐化速度导致存活率和活力显著下降，盐化速度>1 h/次时，仔虾死亡率接近50%；随着盐化速度的放缓，仔虾生长速度加快，盐化速度为6~18 h/次时，生长速度维持稳定，日增重量为1.48~1.51 mg。在盐化方式方面，后期盐化和间隔盐化时，苗种的质量和存活率优于前期盐化和中期盐化，仔虾活力表现为间隔盐化>后期盐化>中期盐化>前期盐化。综合考虑，仔虾的最适盐化幅度为3~6/d，最佳盐化速度为6~12 h/次，后期盐化和间隔盐化更有助于仔虾保持较好活力和较高存活率。本研究通过探讨凡纳滨对虾苗种盐化标粗的最适盐化幅度、盐化速度和盐化方式，丰富了凡纳滨对虾高盐环境抗逆性研究，为凡纳滨对虾苗种的盐化标粗生产实践提供了理论支持。

Effects of High-Salinity Domestication Gradient, Speed, and Mode on Weight Gain, Activity, and Survival Rate of Litopenaeus vannamei Postlarvae

To investigate the optimum high-salinity domestication gradient, speed, and mode of Litopenaeus vannamei postlarvae, a salinization experiment was designed. Salinity increased from 30 to 60. Different high-salinity domestication gradients (3/d, 6/d, 9/d, 12/d, and 15/d), speeds (1, 3, 6, 12, and 18 h/time), and modes (early salinization, medium-term salinization, later salinization, and interval salinization) were used. The weight gain, activity, and survival rate of L. vannamei postlarvae were tested during high-salinity domestication. The results showed that the different high-salinity domestication gradients, speeds, and modes had significant effects on the weight gain, activity, and survival rate of postlarvae (P<0.05). The optimal high-salinity domestication gradient was 3~6/d; the survival rate of postlarvae remained at 74.07% to 78.83% in this gradient. When the high-salinity domestication gradient exceeded 9/d, the survival rate of postlarvae decreased sharply (P<0.05), and was only 43.37% in the high-salinity domestication gradient of 15/d. In addition, the rapid high-salinity domestication speed decreased the survival rate and activity. When the domestication speed was faster than 1 h/time, the survival rate of postlarvae was reduced to nearly 50%; as the domestication speed decreased, the growth rate of postlarvae increased. When the high-salinity domestication speed was 6~18 h/time, the daily weight gain of postlarvae was stable at 1.48~1.51 mg. The later salinization and interval salinization were superior to the early salinization and medium-term salinization regarding the postlarvae activity and survival rate, the postlarvae activity was as follows: interval salinization>later salinization>medium-term salinization>early salinization. Overall, the optimal high-salinity domestication gradient was 3~6/d, the best high-salinity domestication speed was 6~12 h/time, which will help postlarvae to reach the scheduled standard and achieve the target weight gain with later salinization and interval salinization.