温度·盐度对海蜇无性生殖的影响

Effects of Temperature and Salinity on Asexual Reproduction of Rhopilema esculenta

[目的]了解多种环境因素对海蜇无性生殖的交互作用。[方法]在实验室条件下,对温度、盐度双因素对螅状体足囊的形成与萌发和对横裂生殖等2个无性生殖过程的影响进行研究。[结果]随温度、盐度的升高,螅状体形成的足囊数量增多,形成足囊的螅状体率越高。足囊形成过程中,温度与盐度的交互作用不明显。足囊的萌发可能与足囊囊径的大小有关,足囊囊径达到一定的阈值才能萌发,足囊囊径大小是萌发的必要前提;在横裂生殖过程中温度起着决定性作用,同温度下不同盐度的各处理组之间的横裂生殖过程相似。随温度的升高,碟状体释放越早;横裂高峰及碟状体释放高峰越早;横裂周期及碟状体释放周期持续时间越短。总之,温度升高有利于横裂生殖的进行,且在相同时间内随温度升高释放碟状体数量增多。在横裂生殖与碟状体释放过程中,温、盐度交互作用明显;测量释放的初生碟状体伞径,发现盐度越高初生碟状体伞径越大,相反,温度较低时初生碟状体伞径较大。温度、盐度对初生碟状体伞径的影响均明显,且交互作用明显。[结论]在海蜇的无性生殖过程中,24℃-22条件最有利,16℃-18条件最不利。

[ Objective] The research aimed to study the environmental factors and their interaction on the asexual reproduction of Rhopilema esculenta. [ Method] The seyphistomae of Rhopilema esculenta were cultivated under different temperature and salinity levels in laboratory. And the influence of two environmental factors and their interaction on the podocyst formation of the scyphistomae and strobilation of the ephyrae were observed. [Result] The number of neonatal podocysts and the percentage of scyphistoma that had produced pedocysts increased following the increase of temperature and salinity. There were no significant interaction of temperature and salinity on the stage of pedocysts formation. Podocyst germination might be related to the sizes of podocysts. Only after the diameters of podocysts achieved threshold could the germination of posocyst begin. Temperature played a determinant role in the stage of strobilation. In the same temperature, the performances of strobilation for different in- dividuals cultured in different salinity were similar. With the increase of the temperature, the ephyrae would be released earlier. And the peak times for strobilation and the release of ephyrae would begin earlier. And the durations of strobilation and the release of ephyrae would be shorter. In a world,the higher temperature was beneficial for strobilation of scyphistomae. There were no significant interaction effects of temperature and salinity on strobilation of scyphistomae and the release of ephyrae. The size of neonatal ephyrae would be bigger in higher salinity and lower temperature. Salinity and temperature played a determinant role in the diameter growth of ephyrae. There were significant interaction effects of temperature and salinity on the neonatal ephyrae. [ Conclusion] The most optimum condition for asexual reproduction of Rhopilema esculenta were 24 ℃ （temperature） and 22 （salinity） while the most disadvantageous condition were 16 ℃ （temperature） and 18 （salinity）.