| Project/Area Number |
16405001
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 海外学術 |
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| Research Field |
Environmental dynamic analysis
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| Research Institution | Hiroshima University |
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Principal Investigator |
UYE Shin-ichi Hiroshima University, Graduate School of Biosphere Science, Professor (80116540)
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| Co-Investigator(Kenkyū-buntansha) |
ISEKI Kazuo Hiroshima University, Graduate School of Biosphere Science, Professor (00371948)
YANAGI Tetsuo Kyushu University, Research Institute for Applied Mechanics, Professor (70036490)
OHTSU Kozo Shimane University, Oki Marine Biological Station, Professor (20033194)
IGUCHI Naoki Japan Sea National Fisheries Research Institute, 日本海区水産研究所, Chief researcher (00371899)
上 真一 広島大学, 大学院・生物圏科学研究科, 教授 (80116540)
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| Project Period (FY) |
2004 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥13,990,000 (Direct Cost: ¥13,000,000、Indirect Cost: ¥990,000)
Fiscal Year 2007: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2006: ¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2005: ¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2004: ¥3,300,000 (Direct Cost: ¥3,300,000)
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| Keywords | Nemopilema nomurai / Aurelia aurita / population outbreak / coastal environmental change / East Asian Marginal Seas / 生活史 / ポリプ / 瀬戸内海 |
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| Research Abstract |
The population outbreak of jellyfish has become increasingly significant recently in the Es st Asian Marginal Seas, as typically represented by the massive bloom of the giant jellyfish (Nemopilema nomurai). Actually the bloom of this species took place almost every year since 2002 up to 2007. We have extensive investigations on the biology/ecology of N. nomurai the common jellyfish Aurelia aurita, which cause severe damage to beat fisheries.
(1) Sighting survey of N nomurai medusae in the Yellow and East China Seas Ferry sighting survey reveals that young medusae appear in Chinese coastal waters in June and spread widely over the entire Yellow Sea before transported to the Japan Sea. This sighting survey can be very important to forecast the mass occurrence of the medusae in the Japan Sea.
(2) Life cycle of N. nomurai We succeeded in culturing N. nomurai from polyp to young medusa stage in the laboratory for the first time. The asexual reproduction rate by polyps is much lower than other jellyfish species such as A. aurita, but it is higher at higher temperatures. Podocysts are capable of surviving up to 3 years under unfavorable environmental conditions. The seasonal temperature elevation is an important factor; the critical temperature where polyps develop to medusae is around 15℃.
(3) Endurance of A. aurita polyps to deoxygenated condition The polyps of A. emits can survive under deoxygenated condition, where fish and benthos cannot survive at all. Eutropication of the sea which often cause benthic deoxygenation can be one of the causes to enhance jellyfish populations. Warming is also a factor to boost the medusa population.
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