Estimation of the relationship between fish communities and environmental transition in inland sea lakes using sediment core DNA

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H03649
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 64040:Social-ecological systems-related
• Research Institution: Shimane University
• Principal Investigator: Takahara Teruhiko 島根大学, 学術研究院農生命科学系, 教授 (10536048)
• Co-Investigator(Kenkyū-buntansha): 土居 秀幸 京都大学, 情報学研究科, 教授 (80608505)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 環境DNA / 堆積物コア / 汽水湖

Outline of Final Research Achievements

Our goal was to clarify the relationship between recent environmental changes and fish communities by analyzing environmental DNA (eDNA) with sediment cores collected from five lagoon lakes in the San'in region (Lakes Shinji, Nakaumi, Jinzai, Togo, and Koyama). eDNA metabarcoding (MB analysis) revealed less fish eDNA in the core samples compared with the water samples in the lakes. Additionally, fish eDNA was detected in relatively deep layers of Lake Nakaumi, in comparison with Lake Shinji and others, suggesting that the preservation of fish eDNA in the sediment cores was influenced by the salinity of each brackish lake. On the other hand, the results of species-specific eDNA analysis showed that plant eDNA was preserved to much deeper cores than fish eDNA. Furthermore, it was suggested that core eDNA derived from aquatic plants in brackish water lakes would be useful in elucidating historical environmental changes.

Free Research Field

陸水生態学

Academic Significance and Societal Importance of the Research Achievements

海跡湖の堆積物コアから検出できる魚類eDNAは微量であったため、湖の環境変遷を復元する際には水草eDNAも有用であることを明らかにできた学術的意義は大きいと考えている。さらに、水草種の塩分耐性の違いなどに着目することで近過去環境の大規模転換期（例えば、淡水化や汽水化等）などを解明できる可能性も見出すことができた。一方で、海跡湖5つの結果を比較することで、各湖の塩分の高さは堆積物コアにおける魚類eDNAの保存状況に影響している可能性も明らかになってきた。したがって今後は、宍道湖などの塩分が低い海跡湖において、堆積物コアから微量な魚類eDNAを効果的に検出できる手法の開発が必要であると考えられた。