Unusual population explosion of the giant jellyfish Nemopilema nomurai (Scyphozoa: Rhizostomeae) in East Asian waters
Unusual population explosion of the giant jellyfish Nemopilema nomurai (Scyphozoa: Rhizostomeae) in East Asian waters
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DOI：
10.3354/meps307161
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发表时间：
2006-01-01
影响因子：
2.5
通讯作者：
Izumi, H
中科院分区：
文献类型：
--
作者：
Kawahara, M;Uye, S;Izumi, H
2002年和2003年，日本海发生了巨型水母Nemopilema nomurai（Scyphozoa：Remopiloma stomeae）的数量爆炸，对渔业造成了严重损害。2004年人口进一步激增，但规模小得多。在这两年中，年轻的水母在7月和8月开始出现在对马海峡和朝鲜海峡，随后在对马海流中向北迁移到日本海北方。本研究以人工受精的方法获得该种海鞘，并在实验室中将其培育至水母幼鱼阶段。海鞘的无性繁殖是通过足囊的形成进行的。从13到23摄氏度的温度升高诱导了裂球，然后从一个裂球中释放出3到7个ephylocytes。其特征是具有复杂的管道系统和长的红紫色丝状附属物。解放后40 d，后翅已发育为水母，其中央口已关闭，取而代之的是口翅和肩胛骨上的许多小嘴。结合室内饲养试验和田间调查结果，构建了北梭子蟹的季节生活史和地理分布。在东亚沃茨的Nomurai。探讨了N.在过去的十年中，越来越频繁出现的Nomurai也在讨论之中。
A population explosion of the giant jellyfish Nemopilema nomurai (Scyphozoa: Rhizostomeae) occurred in the Sea of Japan in 2002 and 2003, causing severe damage to fisheries. There was a further population explosion in 2004, but on a much smaller scale. In both years, young medusae began to appear in the Tsushima and Korea Strait in July and August, followed by a northward expatriation in the Tsushima Current to the northern Sea of Japan. We obtained scyphistomae of this species by artificial fertilization, and reared them to the young medusa stage in the laboratory. Asexual reproduction of scyphistomae occurred by means of podocyst formation. A thermal increase from 13 to 23 degrees C induced strobilation, followed by liberation of 3 to 7 ephyrae from a strobila. The ephyrae developed to metephyrae having a complex canal system and characteristically possessing long reddish purple filiform appendages. By 40 d post-liberation, the metephyrae had grown to medusae in which the central mouth had closed and been replaced by numerous mouthlets on both oral wings and scapulets. The results from both laboratory-rearing experiments and field investigations were combined to construct the seasonal life cycle and geographical distribution of N. nomurai in eastern Asian waters. Possible causes for the mass occurrence of N. nomurai, which has tended to be more frequent in the last decade, are discussed.