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2019 Fiscal Year Final Research Report

Latitudinal pattern of methanotrophic food webs driving carbon and nitrogen cycling in lakes

Research Project

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Project/Area Number 16H05774
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section海外学術
Research Field Ecology/Environment
Research InstitutionResearch Institute for Humanity and Nature

Principal Investigator

Okuda Noboru  総合地球環境学研究所, 研究部, 准教授 (30380281)

Co-Investigator(Kenkyū-buntansha) 伊藤 雅之  兵庫県立大学, 環境人間学部, 准教授 (70456820)
藤林 恵  秋田県立大学, 生物資源科学部, 助教 (70552397)
Project Period (FY) 2016-04-01 – 2019-03-31
Keywordsメタン栄養食物網 / メタン酸化細菌 / メタン動態 / NC10 / 窒素補給 / 一回循環湖 / 部分循環湖 / 緯度間変異
Outline of Final Research Achievements

Comparative study was conducted in three lakes, temperate Lake Biwa in Japan, subtropical Fei-Tsui Reservoir (FTR) in Taiwan and tropical Seven Lakes in the Philippines, to understand ecosystem responses, especially of CH4 dynamics, methane oxidizing bacteria (MOB) communities and methanotrophic food webs, to climate changes across latitudinal gradient. The FTR alternated between monomictic and meromictic lakes when winter was cold and warm, respectively. During stratification period following the warm winter, CH4 storage developed and anaerobic MOB dominated in profundal waters. Vertical profiles of methane concentrations and MOB communities in the Seven Lakes were similar to those of FTR in warm years, while the Lake Biwa resembled the FTR in cold years. However, there was no marked latitudinal variation in methanotrophic food webs in relation to their reliance on methane production, suggesting that lakes in lower latitude have the higher potential for atmospheric CH4 emission.

Free Research Field

水域生態学

Academic Significance and Societal Importance of the Research Achievements

従来、熱帯湖沼は周年成層が発達する部分循環湖とみなされていたが、本研究により、熱帯湖沼もモンスーンの影響で循環すること、また、全循環の有無は深度依存的であることを明らかにした。季節風や台風などの物理攪乱時に大気放出されるメタンフラックスを定量的に評価するために、高時間解像度観測とメタン生成・消費のプロセス研究が今後の課題として挙げられた。我が国では、温暖化に伴う湖沼の循環不全と底層の貧酸素化が懸念されており、琵琶湖では、全循環が停止する異常事態も発生している。本研究による熱帯・亜熱帯湖沼の知見は、将来的に予想される温帯湖沼の熱帯化が生態系および社会に及ぼすインパクトを予測する上で有用である。

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Published: 2021-02-19  

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