Verification of the universality of eco-environmental diversity index as a river fish habitat evaluation index using environmental DNA

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K04750
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 22060:Environmental systems for civil engineering-related
• Research Institution: Yamaguchi University
• Principal Investigator: Sekine Masahiko 山口大学, 大学院創成科学研究科, 教授 (30163108)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 生態環境多様性指数EED / 河川魚類生息場評価 / 環境DNA

Outline of Final Research Achievements

The purpose is to empirically show that EED has a positive correlation with the number of fish species in large rivers and out of Yamaguchi Prefecture rivers. The qMiFish method was used to investigate the change in concentration of environmental DNA in the Saba River, etc., and a decrease rate coefficient of environmental DNA in the river was 3.55[hr^-1]. This value is two orders of magnitude larger than the known DNA degradation rate, suggesting that the sedimentation, adsorption, and erosion effects are prominent in rivers. It was confirmed that this decrease rate coefficient is consistent with many existing reports of environmental DNA flow distance. Based on this result, we investigated the relationship between environmental DNA and EED in large rivers such as the Ishikari River system. It was supported that EED can be applied to large rivers outside Yamaguchi Prefecture.

Free Research Field

環境工学・衛生工学

Academic Significance and Societal Importance of the Research Achievements

EEDは既存の多くの河川生息場評価手法とは異なり、魚類についての知識や情報がなくとも流速、水深、底質、植生などの物理環境のみを用いることで、安価に精度よく山口県の小河川の魚種数の多寡を評価できることが実証されている。またEEDを流況シミュレーションと組み合わせて河川改修の魚類への影響を予測するソフトウェアDHABSIMが開発されている。この方法が山口県外河川や大河川でも適用できることが実証されることで、容易に多くの河川改修事業の生息場評価を実施することが可能となり、実効性ある多自然川づくりが実施されるようになると期待される。