2021 Fiscal Year Final Research Report
Study on manganese in otoliths of demersal fishes as an Indicator of hypoxia
| Project/Area Number |
19H03025
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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 | 一般 |
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| Review Section |
Basic Section 40030:Aquatic bioproduction science-related
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| Research Institution | Tohoku University |
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Principal Investigator |
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| Project Period (FY) |
2019-04-01 – 2022-03-31
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| Keywords | 貧酸素 / 内湾 / 耳石 / マンガン / バリウム / マコガレイ |
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| Outline of Final Research Achievements |
To determine environmental history of the coastal fish living in and around anoxic and hypoxic inner bay, I focused on Mn eluted from the sediment under low oxygen conditions. Through rearing experiments, hypoxia increased the Mn concentration in seawater. The otolith Mn concentration also showed a significant increase for the Mn-added group, confirming that the otolith Mn is an indicator of the environmental history of hypoxic water.
Otolith Mn was measured for the marbled flounder inside and outside Tokyo Bay. Mn in otolith was extremely low in the outside the bay, but it was found to increase significantly in the inner bay and the bay mouth, especially in the spring and summer. In addition, the otolith Mn concentration in the natural sea area was significantly higher than in any of the Mn-added groups in the rearing experiment. Therefore, it was considered that environmental stress, in addition to the hypoxic conditions of the inner bay, increased otolith Mn.
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| Free Research Field |
沿岸資源学
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| Academic Significance and Societal Importance of the Research Achievements |
これまでの耳石を用いた環境履歴の解析は、微量元素Srを指標とした塩分履歴が主であったが、本研究によって、内湾の貧酸素条件等に加えてストレス等が耳石Mnを増加させるものと考えられた。これらの結果より、耳石Mnが内湾環境の指標となり得ることが示され、耳石を用いた環境履歴解析において、新しい微量元素の有用性が示された。
さらには貧酸素のみならず、海洋酸性化・化学汚染が耳石の微量元素組成や微細構造に影響している可能性が示された。内湾漁業資源がどのような内湾環境を利用しながら生活しているかを明らかにするツールが開発され、社会的な課題解決につながるものと思われる。
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