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Effects of habitat degradation on trophic structure of communities in mangrove estuaries

Research Project

Project/Area Number 19K06101
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Review Section Basic Section 39060:Conservation of biological resources-related
Research InstitutionFisheries Research and Education Agency

Principal Investigator

Nanjo Kusuto  国立研究開発法人水産研究・教育機構, 水産大学校, 講師 (70725126)

Project Period (FY) 2019-04-01 – 2024-03-31
Project Status Completed (Fiscal Year 2023)
Budget Amount *help
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2021: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2020: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2019: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Keywordsマングローブ / 魚類生産 / 富栄養化 / 食物網 / 食物連鎖 / 安定同位体 / 生物生産
Outline of Research at the Start

熱帯河口域は海洋生態系のなかで最も高い生物生産性を有するが,マングローブ伐採や富栄養化などによってその生産性は大きく損なわれている.しかし,魚類を含めた生物生産構造の実態は未だ把握されておらず,人為的改変がどのように作用して生産性低下をまねくのかは不明である.本研究では,熱帯河口域に生息する魚類の成長を支える生産者と栄養フローを特定し,魚類の二次生産量を野外実験や標識放流実験で直接定量することを試みる.これを天然河川,護岸河川,富栄養化河川の間で比較することで,生息場の改変がマングローブ水域の生物生産のどの過程に歪みを引き起こし,二次生産量を低下させるかを明らかにする.

Outline of Final Research Achievements

The impact of habitat degradation on fish production structures in mangrove areas of natural and eutrophic rivers in the Yaeyama Islands, Okinawa Prefecture, was analyzed using carbon and nitrogen stable isotope techniques. In natural rivers, there were species utilizing marine particle organic matter, microphytobenthos (MPB)-derived organic matter, mangrove, and terrestrial particle organic matter. However, in eutrophic rivers, species that assimilate MPB were more abundant, and trophic flows derived from MPB were more dominant. Additionally, the nitrogen isotope ratios of food sources, prey, and fish were significantly higher than those in natural rivers, indicating that external nutrient inputs elevate the nitrogen isotope ratios across the entire food web.

Academic Significance and Societal Importance of the Research Achievements

本研究により,富栄養化は流入する栄養塩に迅速に応答する生産者による栄養フローを卓越させるだけでなく,食物網全体の窒素源になり替わることで魚類を含めた生物生産構造に影響を及ぼすことが示唆された。マングローブ域は富栄養化を含めた生息場の劣化が著しく進行している海域であるため,こうした人為的改変による生態系の応答に関する知見を蓄積することが,より効果的な保全策の確立につながると考えられる。

Report

(6 results)
  • 2023 Annual Research Report   Final Research Report ( PDF )
  • 2022 Research-status Report
  • 2021 Research-status Report
  • 2020 Research-status Report
  • 2019 Research-status Report
  • Research Products

    (7 results)

All 2024 2023 2022 2020

All Journal Article (5 results) (of which Peer Reviewed: 3 results,  Open Access: 1 results) Presentation (1 results) (of which Int'l Joint Research: 1 results) Book (1 results)

  • [Journal Article] Food habits of fishes in salt marsh estuaries in the western Seto Inland Sea, Japan2024

    • Author(s)
      Nanjo K.,Kawaida S.,Doi H.,Yamamori T.
    • Journal Title

      Ichthyological Research

      Volume: 71 Issue: 2 Pages: 305-316

    • DOI

      10.1007/s10228-023-00936-y

    • Related Report
      2023 Annual Research Report
    • Peer Reviewed
  • [Journal Article] First record of the sea cucumber <i>Holothuria (Selenkothuria) erinaceus</i> Semper, 1868 (Holothuroidea: Holothuriida: Holothuriidae) from a Japanese mangrove forest2023

    • Author(s)
      Kawaida Sun, Yamana Yusuke, Tanita Iwao, Nanjo Kusuto
    • Journal Title

      Laguna

      Volume: 30 Issue: 0 Pages: 61-70

    • DOI

      10.60290/laguna.30.0_61

    • ISSN
      1340-3834, 2185-2995
    • Year and Date
      2023-10-28
    • Related Report
      2023 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Food habits of fishes in a subtropical seagrass bed in Nagura Bay, Ishigaki Island, southern Japan2022

    • Author(s)
      Shimizu Masashi、Nanjo Kusuto、Tanita Iwao、Kon Koetsu、Yamada Hideaki
    • Journal Title

      Journal of the Marine Biological Association of the United Kingdom

      Volume: 102 Issue: 5 Pages: 361-369

    • DOI

      10.1017/s0025315422000601

    • Related Report
      2022 Research-status Report
    • Peer Reviewed
  • [Journal Article] Effects of habitat degradation on fish production in a mangrove estuary2020

    • Author(s)
      Kusuto Nanjo
    • Journal Title

      Impact

      Volume: 3 Issue: 3 Pages: 32-33

    • DOI

      10.21820/23987073.2020.3.32

    • Related Report
      2020 Research-status Report
    • Open Access
  • [Journal Article] The importance of mangroves and mangrove fishes2020

    • Author(s)
      Kusuto Nanjo
    • Journal Title

      The Innovation Platform

      Volume: 3 Pages: 1-2

    • Related Report
      2020 Research-status Report
  • [Presentation] Coastal fishes in mangrove habitats in Japan2022

    • Author(s)
      Nanjo K
    • Organizer
      The 27th Joint International Symposium between National Fisheries University and Pukyong National University
    • Related Report
      2022 Research-status Report
    • Int'l Joint Research
  • [Book] Coastal fishes in Japan. In Kai Y, Motomura H, Matsuura K (Eds) Fish Diversity of Japan: Evolution, Zoogeography, and Conservation2022

    • Author(s)
      Kusuto Nanjo
    • Total Pages
      454
    • Publisher
      Springer
    • Related Report
      2021 Research-status Report

URL: 

Published: 2019-04-18   Modified: 2025-01-30  

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