Abstract
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.
Acknowledgements
We extend our special gratitude to Toyo University for providing access to analytical equipment at the Research Facility Center, Asaka, Toyo University. We also express our sincere appreciation to Mr. Tatsumi Kitamura, Mr. Takao Ouchi, Mr. Hiroki Horibe, and Mr. Ryumu Koida for their invaluable assistance in sample collection and pre-treatment.
Funding
This work was supported by JSPS KAKENHI Grant Numbers 23K03489, 22K18045, and 25K18341.
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Nguyen, T.K.H., Amano, Y., Yano, S. et al. Aerobic Methane Oxidation in the Water Column of the Shallow Eutrophic Temperate Lake Kasumigaura.
Sci Rep (2026). https://doi.org/10.1038/s41598-026-47321-z
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DOI: https://doi.org/10.1038/s41598-026-47321-z
Keywords
- Methane
- Aerobic methane oxidation
- Shallow lake
- Methanotroph
Source: Ecology - nature.com
