LARVAE MORTALITY OF PORTUNUS TRITUBERCULATUS UNDER DIFFERENT DESICCATION TEMPERATURES
三疣梭子蟹(Portunus trituberculatus)幼体不同干露温度下死亡率的研究

The swimming crab Portunus trituberculatus is distributed in the coastal waters of Korea Peninsula, Japan and China, and is mainly distributed in the Bohai, Yellow and East Seas in China. This species is dominant in world portunid crabs fisheries and one of the most commercially important fisheries in China. P. trituberculatus culture was encouraged by the increased market demand and price, and availability of good feeds. No-water transportation is the most impor- tant way of larvae and grown crab in the process of transportation. Mortality of larvae and edible quality of grown crab are significantly affected by their tolerance to desiccation. In this study, four temperatures of 15, 20, 25 and 30℃ were designed. Death time, mortality, the body water content, dehydration rate and weight consumption rate in the different developmental stages from 3rd zoeal (ZⅢ) to 2nd young crab (CⅡ) were determined to analyze the relationships of temperature, developmental stage and mortality. The results showed that larvae mortality increased with the increasing desiccation time in the developmental stages (P<0.05). The body water content, dehydration rate and weight consumption rate of 1st young crab (CⅠ) were higher than those of CⅡat the different temperatures (P<0.05). Desiccation time of CⅡwas the longest at 20℃, and death time and half lethal time was about 11h and 7—8h, respectively. Desiccation time of CⅠ was the shortest at 15℃ and the longest at 20℃, and death time was 0.5h and 4h, respectively. Desiccation tolerance of larvae was CⅡ > CⅠ > ZⅣ > ZⅢ = M at the same temperature. Therefore, larvae didn’t survive well below 15℃ and desiccation tolerance decreased above 25℃. Namely, it was 20℃ that larvae can survive for a long time.