| Project/Area Number |
18K11665
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 63040:Environmental impact assessment-related
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| Research Institution | Shimane University |
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Principal Investigator |
YAMAGUCHI Keiko 島根大学, 学術研究院環境システム科学系, 教授 (80322220)
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| Co-Investigator(Kenkyū-buntansha) |
瀬戸 浩二 島根大学, 学術研究院環境システム科学系, 准教授 (60252897)
香月 興太 島根大学, 学術研究院環境システム科学系, 講師 (20423270)
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| Project Period (FY) |
2018-04-01 – 2023-03-31
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| Project Status |
Completed (Fiscal Year 2022)
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| Budget Amount *help |
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2021: ¥130,000 (Direct Cost: ¥100,000、Indirect Cost: ¥30,000)
Fiscal Year 2020: ¥520,000 (Direct Cost: ¥400,000、Indirect Cost: ¥120,000)
Fiscal Year 2019: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2018: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
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| Keywords | 貧酸素 / 成長線 / サルボウガイ / Anadara kagoshimensis / 微量元素 / 酸揮発性硫化物 / AVS / 殻体成長線 / 柱状試料 / 中海 / 殻体 / Anadara / 貧酸素化 / 人為的改変 / 二枚貝 / 有機汚染 / 干拓堤防 / 硫化水素 / 塩分 / ストレス / 成長停止線 / 人為的環境改変 |
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| Outline of Final Research Achievements |
Both laboratory and field experiments using Anadara kagoshimensis showed that there was a positive correlation between the term of exposure to hypoxia and the thickness of the layer at the growth line, calculated as the relative value of the individual growth rate. From columnar samples collected at three locations in Lake Nakaumi, bivalve communities were changed from mud-bottom species such as A. kagoshimensis and Paphia undulata in the low layer into opportunistic and pollution index species such as Theora fragilis and Raetellops pulchellus in the upper layers. Several growth lines indicating hypoxic environment were observed in the cross-section of the shell body that was collected from the lower layer of the columnar sample. This revealed that hypoxia had occasionally occurred in Lake Nakaumi before the construction of reclamation banks. It was also shown that the Mn concentration in the shell collected in the hypoxic region in Lake Nakaumi takes a higher value.
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| Academic Significance and Societal Importance of the Research Achievements |
近年、内湾や湖沼では貧酸素水塊の発生や長期化が増え、水生生物への影響が問題となっている。不十分な環境影響評価のまま実施された干拓・堤防建設などが環境にあたえた影響は、事後に十分に把握できない現状がある。本研究は、貝殻のような長期保存され入手可能な硬組織から,貧酸素の発生状況を読み取ることを可能にした。貧酸素に強いサルボウガイの貝殻から貧酸素を耐えた成長停止線を読み取り、また、貝殻の炭酸カルシウムに混ざるMn濃度で貧酸素の程度を推定する方法を提案した。実例として、人為的改変の少なかった時代にも中海で貧酸素化が起こっていたことをサルボウガイ殻体から読み取った。
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