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<p>Lake Kasumigaura, the second-largest lake in Japan, is shallow, well-oxygenated, and eutrophic. Since shallow lakes are hotspots for methane（CH<sub>4</sub>）emissions, understanding CH<sub>4</sub> oxidation - the process that reduces CH<sub>4</sub> emissions - is essential. This study examines aerobic CH<sub>4</sub> oxidation in Lake Kasumigaura to clarify seasonal fluctuations over six years and the factors that influence it. There was a seasonal dynamic in aerobic CH<sub>4</sub> oxidation in Lake Kasumigaura, with the highest rates in autumn and the lowest in spring. The peak values for both the specific CH<sub>4</sub> oxidation rate (0.0764 ± 0.04&#xa0;h<sup>-1</sup>)&#xa0;and the CH<sub>4</sub> consumption rate (14.9 ± 13.3 nM CH<sub>4</sub> h<sup>-1</sup>)&#xa0;occurred in autumn. Moderate activity was recorded in both summer and winter. Using quantitative PCR and Next-Generation Sequencing, it was found that, unlike in other freshwater lakes, Lake Kasumigaura’s methanotrophic community is mainly composed of <i>Methylocystis</i>, a Type II methanotroph. Redundancy analysis revealed niche differentiation: <i>Methylocystis</i> (Type II) correlates strongly with TN and NO<sub>3</sub><sup>–</sup>, while Type I methanotrophs are less abundant and more sensitive to dissolved CH<sub>4</sub> and water temperature (W.T.). Variations in the dominant methanotrophs (revealed by <i>pmoA</i> gene analyses) in lake water, along with the complex relationships between environmental factors and these communities, highlight the unique biogeochemical properties of Lake Kasumigaura.</p>

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Aerobic Methane Oxidation in the Water Column of the Shallow Eutrophic Temperate Lake Kasumigaura

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年5月5日

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  • Thi Khanh Huyen Nguyen,
  • Yukina Amano,
  • Shoya Yano,
  • Thi Hoang Yen Tran,
  • Thanh Luu Pham,
  • Kazuya Shimizu,
  • Yuma Fujioka,
  • Yoichi Katakura,
  • Motoo Utsumi,
  • Qintong Li

摘要

Lake Kasumigaura, the second-largest lake in Japan, is shallow, well-oxygenated, and eutrophic. Since shallow lakes are hotspots for methane（CH4）emissions, understanding CH4 oxidation - the process that reduces CH4 emissions - is essential. This study examines aerobic CH4 oxidation in Lake Kasumigaura to clarify seasonal fluctuations over six years and the factors that influence it. There was a seasonal dynamic in aerobic CH4 oxidation in Lake Kasumigaura, with the highest rates in autumn and the lowest in spring. The peak values for both the specific CH4 oxidation rate (0.0764 ± 0.04 h-1) and the CH4 consumption rate (14.9 ± 13.3 nM CH4 h-1) occurred in autumn. Moderate activity was recorded in both summer and winter. Using quantitative PCR and Next-Generation Sequencing, it was found that, unlike in other freshwater lakes, Lake Kasumigaura’s methanotrophic community is mainly composed of Methylocystis, a Type II methanotroph. Redundancy analysis revealed niche differentiation: Methylocystis (Type II) correlates strongly with TN and NO3–, while Type I methanotrophs are less abundant and more sensitive to dissolved CH4 and water temperature (W.T.). Variations in the dominant methanotrophs (revealed by pmoA gene analyses) in lake water, along with the complex relationships between environmental factors and these communities, highlight the unique biogeochemical properties of Lake Kasumigaura.