Buffer waters in shallow underground areas in terrestrial and marine ecotone areas: Identification of salinity conditions and ecological functions.

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K21337
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 40:Forestry and forest products science, applied aquatic science, and related fields
• Research Institution: Kyushu University
• Principal Investigator: Onikura Norio 九州大学, 農学研究院, 教授 (50403936)
• Co-Investigator(Kenkyū-buntansha): 小山 彰彦 九州大学, 農学研究院, 助教 (50814662)
• Project Period (FY): 2020-07-30 – 2023-03-31
• Keywords: 塩分 / エコトーン / 地中間隙水 / ベントス / ヨシ

Outline of Final Research Achievements

First, we explicitly identified stable salinity conditions of buffer waters in shallow underground areas at the boundary between land and sea. In both locations where the backlands were mountain forests and where the backlands were plains, the salinity of surface water fluctuated with the ebb and flow of the tide, whereas the pore water was stable at low salinity. Surface water salinity was influenced by tides and precipitation, while pore water salinity was not influenced by tides and was stable. Porewater on the mountain side was unaffected by not only tide bute also precipitation.
The benthic fauna of the tidal flats differed between the mountain side and the plain side, with reeds growing on the mountain side, and the benthic species diversity was high. The low salinity of the pore water supports the growth of reeds, and as a result, it can be inferred that the species diversity is high due to the presence of organisms that depend on the reed zone.

Free Research Field

応用生態学

Academic Significance and Societal Importance of the Research Achievements

本研究により、陸域と海域の境界部、すなわち、エコトーン部の地中浅所には、塩分濃度が　安定した汽水域（陸域・海域緩衝水域）が形成されることが明示でき、その緩衝水域の塩分は、背後地の相違により異なることが明確となった。そして、その塩分の相違が異なる生物相を生み出すことで、広域での種多様性を高めていると結論される。これらの研究成果は、学術的意義だけでなく、実学的な貢献度が極めて大きい。例えば、近年各地で行われているヨシ原の自然再生を行う際の候補地選定に有益な知見を提供できる。また、海岸線の開発工事の際、本研究成果を参考に、広域での種多様性に配慮した計画立案することが望まれる。