| Project/Area Number |
06640600
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Stratigraphy/Paleontology
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| Research Institution | NAGASAKI UNIVERSITY |
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Principal Investigator |
MATSUOKA Kazumi Nagasaki University, FACULTY OF LIBERAL ARTS,DEPARTMENT OF GEOLOGY,PROFESSOR, 教養部, 教授 (00047416)
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| Co-Investigator(Kenkyū-buntansha) |
TAKEMURA Kenji INSTITUTE OF GEOPHYSICS,GRADUATE SCHOOL OF SCIENCE,KYOTO UNIVERSITY,ASSOCIATE PR, 大学院・理学研究科, 助教授 (00201608)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1995: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1994: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | DINOFLAGELLATE / CYST / ENCLOSED SEA / OMURA BAY / NAGASAKI BAY / BIOLOGICAL MARINE POLLUTION / RED TIDE / ENVIROMENTAL CHANG |
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| Research Abstract |
The purpose of this study is to search for the possibility that the assemblage of dinoflagellate cysts preserved in surface sediments can reflect the environmental change of the eutrophication. For this research, five core samples were collected from Omura Bay and Nagdsaki Bay, West Kyushu. After confirming that these core samples were not disturbed, sedimentation rate on each cores was calculated on the basis of ^<210>Pb measurements.
Around 1968 when the Koyagi Strait were reclimed, the dinoflagellate cyst assemblage recovered from the cores of Nagasaki Bay changed from autotrophic group mainly comprising Spiniferites, Lingulodinium to heterotrophic groups of congruentid and some of gymnodinioid. This change in dinoflagellate cysts was probably due to the eutrophication after changing water circulation pattern in Nagasaki Bay owing to disappear the Koyagi Strait. In Omura Bay, only Pheopolykrikos hartmannii gradually increase toward the surface. This probably shows that there was no remarkable change like to Nagasaki Bay, but only gradual increase of eutrophication since 1970's.
Based on these observations, the change of dinoflagellate cyst assemblage, in particular a ratio between the autotrophic group mainly consisting Spiniferites, Lingulodinium and Operculodinium and the heterotrophic group such as congruentid and diplopsalid species is one of the good marker for understanding the eutrophication in the enclosed seas.
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