日本蟳对3种贝类的摄食选择及摄食节律的研究

在实验室条件下，研究了体质量为60～75g的日本蟳Charybdisjaponica对3种贝类光滑河蓝蛤Pota-mocorbulalaevis、四角蛤蜊Mactraquadrangularis及菲律宾蛤仔Ruditapesphilippinarum的摄食喜好性和对光滑河蓝蛤的摄食节律。结果表明：在海水盐度为28～29，水温为22～24qC，溶氧为6．8～7．8mg／L的条件下，有或无底质时雌、雄蟹对光滑河蓝蛤的饵料选择指数均大于0，为其喜好的食物，而对四角蛤蜊和菲律宾蛤仔的饵料选择指数均小于0。采用定时投喂方式，每隔4h投喂一次光滑河蓝蛤，日本蟳在有、无底质条件下均表现出昼夜摄食节律。有底质组的摄食高峰出现在23：00—3：00，平均每小时最高摄食量为0．12g，7：00—19：00有少量摄食；无底质组的摄食高峰出现在19：00—23：00，平均每小时最高摄食量为0．096g，7：00-15：00有少量摄食。有底质组的日本蜉19：00—7：00的摄食量占全天的比值显著高于7：00—19：00（P〈O．05），19：00—7：00的摄食频率极显著高于7：00-19：00（P〈O．01）；无底质组的日本蟳19：00—7：00的摄食量比值与摄食频率均高于7：00—19：00，但差异不显著（P〉O．05）。

Selective feeding on three bivalves and feeding rhythm Asian swimming crab Charybdis japonica

Selective feeding on three bivalves Potamocorbula laevis, Mactra quadrangularis and Ruditapes philippi- narum was studied in Asian swimming crab Charybdis japonica with body weight from 60 g to 75 g at water tempera- ture of 22-24 ℃, a salinity of 28-29, and dissolved oxygen level of 6.8-7.8 mg/L in a laboratory. The male and female crab were shown to have preference for P. laevis, whether with or without substrate. It was found that the crab showed active feeding rhythm in a day/night cycle when fed once every four hours. For the group with sub- strates, the crab presented a feeding peak from 23：00 to 3：00 with a maximum feeding rate of 0.12 g/h, and feed- ing was not observed from 7：00 to 19：00. In the group without substrates, the crab had a feeding peak around 19：00 to 23 ： 00 with a maximum feeding rate of 0. 096 g/h, but the crab had feeding activities from 7 ： 00 to 15：00. There was a higher feeding ratio （P〈0.05） and feeding frequency（P〈0.01 ）in group with substrates from 19：00 to 7：00 than that from 7：00 to 19：00. However, there was not significant difference in the group without substrates （ P〉0.05 ）.