Submerged macrophytes remediation is a commonly used technique for improving water quality and restoring habitat in aquatic ecosystems. However, the drivers of success in the submerged macrophytes assembly process and their specific impacts on methane emissions are poorly understood. Thus, we conducted a mesocosm experiment to test the growth plasticity and carbon fixation of widespread submerged macrophytes (Vallisneria natans) under different nutrient conditions. A refined dynamic chamber method was utilized to concurrently collect and quantify methane emission fluxes arising from ebullition and diffusion processes. Significant correlations were found between methane flux and variations in the physiological activities of V. nantas by the fluorescence imaging system. Our results show that exceeding tolerance thresholds of ammonia in the water significantly interfered with the photosynthetic systems in submerged leaves and the radial oxygen loss in adventitious roots. The recovery process of V. natans accelerated the consumption of dissolved oxygen, leading to increase in the populations of methanogen (153.3 % increase of mcrA genes) and subsequently elevating CH4 emission fluxes (23.7 %) under high nutrient concentrations. Conversely, V. natans increased the available organic carbon under low nutrient conditions by radial oxygen loss, further increasing CH4 emission fluxes (94.7 %). Quantitative genetic and modeling analyses revealed that plant restoration processes drive ecological niche differentiation of methanogenic and methane oxidation microorganisms, affecting methane release fluxes within the restored area. The speciation process of V. natans is incapable of simultaneously meeting improved water purification and reduced methane emissions goals.

中文翻译：

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温室效应被忽视的驱动因素：由淹没的大型植物介导的营养-甲烷关系


淹没大型植物修复是改善水质和恢复水生生态系统栖息地的常用技术。然而，人们对水下大型植物组装过程的成功驱动因素及其对甲烷排放的具体影响知之甚少。因此，我们进行了一项中宇宙实验，以测试广泛分布的沉水大型植物 （Vallisneria natans） 在不同营养条件下的生长可塑性和碳固定性。采用精炼的动态室方法同时收集和量化由沸腾和扩散过程产生的甲烷排放通量。荧光成像系统发现甲烷通量与 V. nantas 生理活性变化之间存在显著相关性。我们的结果表明，超过水中氨的耐受阈值会显着干扰沉水叶片中的光合系统和不定根中的径向氧损失。V. natans 的恢复过程加速了溶解氧的消耗，导致产甲烷菌种群增加（mcrA 基因增加 153.3%），随后在高营养浓度下提高了 CH4 发射通量 （23.7%）。相反，在低营养条件下，菱角通过径向氧损失增加了有效有机碳，进一步增加了 CH4 发射通量 （94.7 %）。定量遗传和建模分析表明，植物恢复过程推动了产甲烷和甲烷氧化微生物的生态位分化，影响了恢复区域内的甲烷释放通量。V. natans 的物种形成过程无法同时满足改进的水净化和减少甲烷排放的目标。