Study on manganese in otoliths of demersal fishes as an Indicator of hypoxia

• Project/Area Number: 19H03025
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 40030:Aquatic bioproduction science-related
• Research Institution: Tohoku University
• Principal Investigator: Katayama Satoshi 東北大学, 農学研究科, 教授 (30224455)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Project Status: Completed (Fiscal Year 2021)
• Budget Amount: ¥15,730,000 (Direct Cost: ¥12,100,000、Indirect Cost: ¥3,630,000); Fiscal Year 2021: ¥5,070,000 (Direct Cost: ¥3,900,000、Indirect Cost: ¥1,170,000); Fiscal Year 2020: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000); Fiscal Year 2019: ¥5,850,000 (Direct Cost: ¥4,500,000、Indirect Cost: ¥1,350,000)
• Keywords: 貧酸素 / 内湾 / 耳石 / マンガン / バリウム / マコガレイ / 東京湾

Outline of Research at the Start

環境履歴から内湾の貧酸素水動態を推定する手法を確立するために、貧酸素条件で底質から溶出するマンガンに注目する。飼育実験によって、マンガンの底質からの溶出、水中のマンガンの耳石への蓄積といったプロセスを明らかにする。
そして、東京湾の底魚数種の耳石に含有するマンガンを年輪構造に沿って測定し、各個体の貧酸素水環境履歴（どの季節に貧酸素水域を利用したか）を推定する。
これらの結果によって、耳石のマンガンが内湾の貧酸素水の指標として用いる有用性が確認される。

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.

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。

Research Products

• [Journal Article] Impacts of H+ on the otolith morphology of the marbled flounder, Pseudopleuronectes yokohamae (2022)
  • Author(s): Shengjian Jiang, Peiqi Hong, Satoshi Katayama
  • Journal Title: Aquaculture Science Volume: 70
  • Peer Reviewed
• [Journal Article] What is the relationship between hypoxia, water chemistry, and otolith manganese content? (2022)
  • Author(s): Shengjian Jiang, Peiqi Hong, Satoshi Katayama
  • Journal Title: Journal of Fish Biology Volume: - Issue: 5 Pages: 1138-1149
  • DOI: 10.1111/jfb.15041
  • Peer Reviewed
• [Journal Article] 東北沖深海性魚類の組成と生態的特性 (2022)
  • Author(s): 片山知史
  • Journal Title: 日本水産学会東北支部会報 Volume: 72 Pages: 5-5
• [Journal Article] Experimental study on the influence of water temperature on the otolith formation of the marbled flounder (Pseudopleuronectes yokohamae) (2021)
  • Author(s): Peiqi Hong, Shengjian Jiang, Satoshi Katayama
  • Journal Title: International Aquatic Research Volume: 13 Pages: 119-128
  • Peer Reviewed
• [Journal Article] Comparison of Age and Growth of the Marbled Flounder Pseudopleuronectes yokohamae in the Coastal Waters of Japan (2019)
  • Author(s): PEIQI HONG, SATOSHI KATAYAMA, MASAYUKI YAMAMOTO, MITSUHIRO ISHII, TOSHINORI BABA, MITSUHIRO SAEKI, MITSUHARU SUZUKI, MITSUHIRO NAKAYA, YUTA YAGI
  • Journal Title: Asian Fisheries Science Volume: 32 Issue: 2 Pages: 72-80
  • DOI: 10.33997/j.afs.2019.32.02.004
  • Peer Reviewed
• [Book] 沿岸資源調査法 (2022)
  • Author(s): 片山知史・松石 隆
  • Total Pages: 100
  • Publisher: 恒星社厚生閣
  • ISBN: 9784769916772