Changes of the physical conditions and biodiversity of tidal flats before and after a high-dam removal

2014 Fiscal Year Final Research Report

• Project/Area Number: 24310174
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Resource conservation science
• Research Institution: Kyushu University
• Principal Investigator: ONIKURA Norio 九州大学, (連合)農学研究科(研究院), 助教 (50403936)
• Co-Investigator(Kenkyū-buntansha): SHIMATANI Yukihiro 九州大学, 大学院工学研究院, 教授 (40380571) ; OHTSUKI Kazuaki 東京理科大学, 理工学部, 助教 (10618507) ; MINAGAWA Tomoko 熊本大学, 大学院自然科学研究科, 准教授 (10355828) ; IYOOKA Hiroki 福岡大学, 工学部, 助教 (40432869)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 干潟 / ダム撤去 / マクロベントス / 底質 / 堆積 / 流砂 / ハゼ類 / カニ類

Outline of Final Research Achievements

We investigated the physical conditions and biodiversity of tidal flats around the estuary of the Kuma River. The deconstruction of a high-dam located approximately 20 km upstream from the river mouth begun in 2012, therefore we selected the river mouth as our survey area with the expectation of sediment outflow from the removed dam. The increase in base ground level in tidal flats mostly occurred in high water season, suggesting that sediments supplied from the river contribute to the homeostatic ground level height of tidal flats. Sediment composition in most sites had changed from mud to sand as the dam removal progressed, indicating that the sand which had previously accumulated at the dam eventually arrived at the tidal flats. Approximately 20% of the survey sites had faunal changes and an increase in species richness as dam removal progressed. We conclude that the sediment outflow from the river upstream contributes to the homeostatic mechanisms of the tidal flat ecosystem.

Free Research Field

水産学・応用生態学・資源保全学