拟穴青蟹大眼幼体和第Ⅰ期仔蟹底质选择的研究

拟穴青蟹大眼幼体和仔蟹对海泥和泥沙底质的选择性显著高于各种粒径的沙底（粒度0.06～2.00mm）.其原因可能与海泥和泥沙底质在流动海水中物理稳定性高于沙砾有关.通过以埋栖选择性和相对埋栖率为指标考察了大眼幼体和仔蟹的栖息方式,发现白昼大眼幼体埋栖在底质中的比例显著高于夜间,也高于仔蟹;夜间大眼幼体栖息方式与仔蟹差别不明显;并发现大眼幼体栖息方式存在着昼夜差异和昼夜节律性.这揭示了拟穴青蟹大眼幼体对底质的选择性和在底质上栖息的方式表现出对FTT机制的适应.

Study on the substratum preference of the mud crab,Scylla paramamosain,in stage of megalopa and first juvenile

The settlement mode of the mud crab （ Scylla paramamosain） megalopa and juveniles were studied by observing the frequency of burrowing-in or settling-on the surface of substrata. It shows that the mud crab preferred to habitat the mud or mud/sand substratum much than the sand substrata of 3 granular sizes （0.06 - 2.00mm）. The difference is possibly due to the physical stability of mud or mud/sand substratum rather than the unstable sand by the current. The burrowing-in preference and relative burrowing rate of the crab megalopae show that the burrowingin frequency is significantly higher during daytime than nighttime. It is also higher than that of juvenile. No significant difference exists between the megalopae and the juvenile in their preferences for burrowing-in substrata during nighttime. The settlement mode of megalopae displays substratum selection and utilization of the megalopae day-night difference and day-night rhythm. It reveals that the are an adaptation to the FTT （flood-tide transport） mechanism.