2018 Fiscal Year Final Research Report

Establishment of multi-faceted evaluation of ecological effects of instream obstructions on benthic fishes at population and community level

Research Project

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Project/Area Number	16H02966
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Research Field	Environmental impact assessment
Research Institution	Ibaraki University
Principal Investigator	NATSUMEDA Takaharu 茨城大学, 教育学部, 准教授 (00468993)
Co-Investigator(Kenkyū-buntansha)	井口恵一朗長崎大学, 水産・環境科学総合研究科(環境), 教授 (00371865) 田原大輔福井県立大学, 海洋生物資源学部, 准教授 (20295538) 阿部信一郎茨城大学, 教育学部, 教授 (40371869) 松崎慎一郎国立研究開発法人国立環境研究所, 生物・生態系環境研究センター, 主任研究員 (40548773) 武島弘彦総合地球環境学研究所, 研究部, 外来研究員 (50573086)
Project Period (FY)	2016-04-01 – 2019-03-31
Keywords	河川工作物 / 底生魚類 / 遡上阻害 / 生息環境改変 / PITタグ / マイクロサテライトDNA / 安定同位体比
Outline of Final Research Achievements	This study aims to establish multi-faceted evaluation of ecological effects of instream obstructions (weirs) on benthic fishes at population and community level, based on PIT tags, DNA markers, and stable isotopes ratio. Comparison of fish community structure below and above weirs indicates remarkable decline in diversity and population number of diadromous fishes above weirs due to inhibition of upstream migration and anthropogenic modification of instream habitat features by weirs. PIT tag surveys revealed that a weir with two-segment drop in height (40+75cm) prevented Japanese fluvial sculpin to ascend a weir. Genetic population structure analysis, based on 21 microsatellite DNA markers, indicated the evidence for genetic disturbance between exotic specimens and domestic specimens. We also examined validity of stable isotopes ratio (δ13C, δ15N) from non-destructive part of nine fish species (caudal fin), as an alternative of muscle tissues, conventionally used destructive part.
Free Research Field	魚類生態学
Academic Significance and Societal Importance of the Research Achievements	本研究は堰の落差がもたらす魚類の遡上阻害だけでなく、堰の存在による堰上区間の生息環境の改変（湛水域の形成）が魚類群集の組成や種の生息密度に影響を及ぼすことを明らかにした。また、本研究で有効性を検証した非破壊的な試料（尾鰭）に基づく安定同位体比分析は、保全生態学領域の進展に寄与することが期待される。