Resistance test at early larval stage of blue swimming crab, Portunus pelagicus

Abstract

The early larval stage is the crucial phase in the larviculture of blue swimming crab, Portunus pelagicus. The combination of stress resistance tests have been done to determine the maximum period of starvation and dissolved oxygen, the preferable range of temperature, salinity, pH and ammonia for P. pelagicus larvae survival at early larval stages. Larvae were exposed to various treatments as mentioned above to examine larvae competency against the stressor. In starvation test, at 12 hours, more than 50 percent of larvae were observed dead. While in the dissolved oxygen test, no larvae survived more than 6 hours without aeration treatment. The optimum temperature for larvae was 30C due to high survival rate (43.18%) was found in the end of experiment. There were no larvae survival at salinity level 0 ppt, 10 ppt and 50 ppt respectively. The highest larvae survival was found at 30 ppt treatment (60.51%). The suitable pH for larval rearing condition was ranged from 8.0-8.2 (survival rate were 48.60% and 70.47%, respectively) owing to larval survival rate in others treatments were very low. In the last experiment, lower concentration of ammonia treatments (0.02, 0.2 ppm) showed higher survival rate (58.54% and 23.90%) whereas the larvae in 2 ppm and 20 ppm treatments died with 24 hours and 6 hours after spike