三疣梭子蟹(Portunus trituberculatus)幼体不同干露温度下死亡率的研究

通过设置15℃、20℃、25℃、30℃4个干露温度梯度,检测不同发育阶段三疣梭子蟹幼体的露空时间、死亡率、含水量、失水率及体重消耗率等指标,分析干露温度、发育阶段与幼体死亡率的关系。结果表明,各发育阶段的幼体死亡率均随干露时间的增加而升高(P<0.05);不同温度条件下,Ⅰ期幼蟹(CⅠ)的含水量、失水率和体重消耗率均高于Ⅱ期幼蟹(CⅡ)(P<0.05);CⅡ20℃时的露空时间最长,为11h,半致死时间为7—8h;30℃时最短,为2h;CⅠ15℃时的露空时间最短,为0.5h;20℃时最长,为4h。相同温度下,幼体各发育阶段的耐干露能力为CⅡ>CⅠ>ZⅣ>ZⅢ=M。结果说明,温度≤15℃不利于幼体的存活,温度≥25℃干露耐受性降低。因此,20℃更有利于幼体获得长存活时间。

LARVAE MORTALITY OF PORTUNUS TRITUBERCULATUS UNDER DIFFERENT DESICCATION TEMPERATURES

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.