2005 Fiscal Year Final Research Report Summary
Establishment of stratigraphical and paleontological methods to understand the dynamics of coastal ecosystem and the abnormal sea-level changes occurred in the 20^<th>.
| Project/Area Number |
15204046
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Stratigraphy/Paleontology
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| Research Institution | Shimane University |
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Principal Investigator |
NOMURA Ritsuo Shimane University, Faculty of Education, Professor, 教育学部, 教授 (30144687)
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| Co-Investigator(Kenkyū-buntansha) |
IRIZUKI Toshiaki Shimane Univ., Interdisciplinary Faculty of Science and Engineering, Associate Professor, 総合理工学部, 助教授 (60262937)
SETO Kouji Shimane University, Research Center for Coastal Lagoon Environment, Associate Professor, 汽水域研究センター, 助教授 (60252897)
OHTANI Shuji Shimane University, Faculty of Education, Professor, 教育学部, 教授 (50185295)
YAMAGUCHI Keiko Shimane University, Faculty of Life and Environmental Science, Lecturer, 生物資源科学部, 講師 (80322220)
NINAGAWA Kiyotaka Okayama University of Science, Department of Applied Physics, Professor, 理学部, 教授 (80098590)
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| Project Period (FY) |
2003 – 2005
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| Keywords | coastal environment / sea-level change / stratigraphy / paleontology / ecological system / brackish lake / artificial construction / radioactivity dating |
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| Research Abstract |
We carried out several basic studies in order to estimate the response of coastal marine organisms to the sea-level rise in association with a global warming. We particularly stress the following points in this year : sampling of columnar sediments from enclosed coastal lagoons and the sediment analyses ; development of measuring technique for past dating ; experimental studies of in situ brackish organisms as a tool to understand a long-term climatic variation as well as coastal environmental changes. Geochronological study group has promoted wide applications of U-Pb method for zircon, ESR method for quartz and TL method for calcite. Seasonal variation of ^<228>Ra/^<226>Ra ratio in sea-weed and extremely low background measurements of ^<137>Cs in seawater samples were analyzed. Biological group get the results that early summer growth of the shell is rapid when the brackish water temperature is extremely cold. The shell growth of Corbicula increased when the brackish water changed from high salinity to low one. Isolation of culture strains of phytoplankton at 20℃ form brackish lake Shinjiko was performed on BBM agar plates. Environment study group examined the columnar sediments from Lake Shinjiko (Shimane), Lake Saroma (Hokkaido), Ohmura-Bay (Nagasaki) and Matsukawa-ura (Fukushima) for their grain-size, organic materials and organic remains. Evidence of density flow of marine water was recognized when the Hii-gawa River flowed down into Lake Shinji in 1680. The reconstructed ostracode assemblage revealed the appearance of hypoxia environment in the 1960s in Ohmura Bay, which is coeval with the observed evidence of low-oxygen water appearance. We found a different response of coastal organisms to sea-level variations according to the different areas.
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