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Causative factors and conditions of the population explosion of the moon jelly Aurelia aurita in Tokyo Bay

东京湾月水母Aurelia aurita种群爆炸的成因及条件

基本信息

批准号：
06660230
负责人：
OMORI Makoto
金额：
$ 1.28万
依托单位：
Tokyo University of Fisheries
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06660230/
关键词：
moon jellyfish Aurelia aurita polyp ephyla strobilation eutrophication mass occurrence 生態学海分生物学

项目摘要

Factors and conditions to relate mass occurrence of the moon jelly Aurelia aurita in the upper part of Tokyo Bay have been examined through field survey and laboratory experiment. In the field sampling of the jelly and measurement of hydrographic conditions were carried out once or twice a month during three consecutive years from April 1993. Seasonal variation of the size of medusae and occurrence of planulae and ephyrae were determined. Based on these information, rearing experiments of planulae and polyps were carried out under different temperature and food regimes during a few months in each year. As the result, processes of formation of the strobilation and a sexual reproduction by budding were revealed. Other findings included the size of polyps to commence strobilation, duration of strobilation, production rate of strobilae, and number and size of ephyrae.Growth of polyps and timing of the ephyla's liberation are strongly influenced with temperature and feeding condition.Number of buds of polyps increase with increasing feeding duration after the temperature lowered. The polyps settled before autumn of the previous year liberate ephyrae in January, whereas those settled in autumn produce ephyrae in February to April.With favorable higher temperature and food density during the early polyp stage, the polyps growth and increase the number rapidly. The strobilation is induced when the temperature lowered to 15ﾟC or less. If food condition is still preferable after the lowering temperature, large size ephylae are liberated from large numbers of polyps. The population explosion of A.aurita could be attributed to its high reproductive potential under these special conditions.

本文通过野外调查和室内实验，探讨了东京湾上部大耳奥雷利亚水母大量发生的因素和条件。从1993年4月起，连续三年每月对水母进行一次或两次实地取样和水文条件测量。确定了水母大小的季节变化以及浮浪和浮沉的发生。在此基础上，每年进行几个月的不同温度和食物条件下的浮浪和水螅的饲养试验。其结果是，形成过程的横裂和有性繁殖的萌芽被揭示。结果表明，温度和摄食条件对珊瑚虫的生长和幼体的释放有很大的影响，温度降低后，随着摄食时间的延长，珊瑚虫的芽数增加。前一年秋前定居的珊瑚虫在1月释放出尾丝，秋季定居的珊瑚虫在2 ~ 4月释放出尾丝。当温度降低到15 ℃或更低时，会诱导裂球。如果温度降低后食物条件仍然较好，则会从大量水螅中释放出大尺寸的叶状体。在这些特殊的环境条件下，大耳金龟子的种群爆炸可能归因于其高繁殖潜力。