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Aims <p>Variations in greenhouse gas (GHG) emissions and associated microbial mechanisms among lakes dominated by different macrophyte life forms remain poorly understood. This study aimed to examine the&#xa0;GHG emissions and their underlying microbial mechanisms in lakes dominated by macrophytes with distinct life forms.</p> Methods <p>Using 16S rRNA gene sequencing combined with random forest and partial least squares path modeling, we examined the roles of&#xa0;bacterial community in regulating GHG fluxes in lakes dominated by submerged and floating-leaved macrophytes.</p> Results <p>Methane&#xa0;(CH<sub>4</sub>) and carbon&#xa0;dioxide fluxes were significantly lower in lakes dominated by <i>Vallisneria natans</i> (<i>V. natans</i>)&#xa0;(submerged macrophyte) compared to those dominated by <i>Trapa quadrispinosa</i> (floating-leaved macrophyte). Lower CH<sub>4</sub> flux in lakes dominated by <i>V. natans</i> was attributed to the higher abundance of methanotrophs in the sediment, supported by the greater abundance of <i>pmoA</i> gene, particularly from <i>Methylocystis</i>. Methanotrophs played a crucial connecting role in the sediment of lakes dominated by <i>V. natans</i>, as evidenced by bacterial co-occurrence network analysis and their higher predicted functional abundance. Microbial community structure was closely associated with environmental variables and plant traits. Furthermore, <i>V. natans</i> exhibited strong water purification capacity, reducing the trophic status of the lakes. Regionally, replacement of submerged macrophytes with floating-leaved macrophytes could increase CH<sub>4</sub> flux&#xa0;by 0.32&#xa0;kg d⁻<sup>1</sup> during the growing season in the middle and lower reaches of the Yangtze River.</p> Conclusions <p>This study confirmed that reduced CH<sub>4</sub> emissions in lakes dominated by submerged macrophytes were associated with improved water quality and enhanced rhizosphere CH<sub>4</sub> oxidation by methanotrophs, suggesting that submerged macrophyte restoration may simultaneously support water-quality improvment and CH<sub>4</sub> mitigation.</p> Graphical Abstract <p></p>

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Variations in aquatic macrophytes and methanotrophs in sediments drive divergent methane emissions in lakes across the middle and lower reaches of the Yangtze River

  • 期刊论文

  • 发表日期：

    2026年5月7日

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  • Qisheng Li,
  • Xiaomin Zhang,
  • Biao Li,
  • Siwen Hu,
  • Hongyang Deng,
  • Tianxu Zhou,
  • Mengyuan Li,
  • Qinglong L. Wu,
  • Jin Zeng

摘要

Aims

Variations in greenhouse gas (GHG) emissions and associated microbial mechanisms among lakes dominated by different macrophyte life forms remain poorly understood. This study aimed to examine the GHG emissions and their underlying microbial mechanisms in lakes dominated by macrophytes with distinct life forms.

Methods

Using 16S rRNA gene sequencing combined with random forest and partial least squares path modeling, we examined the roles of bacterial community in regulating GHG fluxes in lakes dominated by submerged and floating-leaved macrophytes.

Results

Methane (CH4) and carbon dioxide fluxes were significantly lower in lakes dominated by Vallisneria natans (V. natans) (submerged macrophyte) compared to those dominated by Trapa quadrispinosa (floating-leaved macrophyte). Lower CH4 flux in lakes dominated by V. natans was attributed to the higher abundance of methanotrophs in the sediment, supported by the greater abundance of pmoA gene, particularly from Methylocystis. Methanotrophs played a crucial connecting role in the sediment of lakes dominated by V. natans, as evidenced by bacterial co-occurrence network analysis and their higher predicted functional abundance. Microbial community structure was closely associated with environmental variables and plant traits. Furthermore, V. natans exhibited strong water purification capacity, reducing the trophic status of the lakes. Regionally, replacement of submerged macrophytes with floating-leaved macrophytes could increase CH4 flux by 0.32 kg d⁻1 during the growing season in the middle and lower reaches of the Yangtze River.

Conclusions

This study confirmed that reduced CH4 emissions in lakes dominated by submerged macrophytes were associated with improved water quality and enhanced rhizosphere CH4 oxidation by methanotrophs, suggesting that submerged macrophyte restoration may simultaneously support water-quality improvment and CH4 mitigation.

Graphical Abstract