Abstract：
Floating microplastics (FMPs) in surface water have been extensively studied, but their influence on sedimentary microbial ecosystems is poorly understood. Here, we investigated response patterns of abundant and rare sedimentary microbes to FMP disturbances by performing microcosmic experiments using fluvial sediment with polyethylene (PE), polylactic acid (PLA), polystyrene (PS) and polyvinyl chloride (PVC) MPs. The results indicated that FMPs altered sediment microbial community diversity and composition. Some organic-degrading, nitrifying and denitrifying bacteria significantly decreased in response to FMP disturbances, which may affect the sediment carbon and nitrogen cycles. Rare taxa persisted under FMP disturbances, whereas abundant taxa were more susceptible to FMP disturbances, suggesting a higher sensitivity of abundant taxa to FMP disturbances. Although stochastic processes governed the assembly of the overall microbial communities, the assembly mechanisms of abundant and rare populations have significantly different responses to FMP interference. The relative contribution of deterministic processes was reinforced by enhanced homogenous selection in abundant populations, while it markedly decreased in rare populations under FMP disturbances. Furthermore, FMPs substantially decreased the network complexity, loosened the coexistence relationships, and increased the negative correlations. Rare species play an important role in reshaping complex microbial interactions and coexistence networks in response to FMP disturbances. This research broadens our perspectives for comprehensively evaluating the ecological effects of FMPs in the aquatic environment to formulate further policy controls.
摘要：
地表水中漂浮的微塑料(FMPs)已经得到了广泛的研究，但是它们对沉积微生物生态系统的影响知之甚少。这里,我们通过使用聚乙烯（PE）的河流沉积物进行微观实验，研究了丰富和罕见的沉积微生物对FMP干扰的响应模式，聚乳酸(PLA),聚苯乙烯(PS)和聚氯乙烯(PVC)MPs。结果表明，FMPs改变了沉积物微生物群落的多样性和组成。一些有机物降解，硝化和反硝化细菌对FMP干扰的反应显着减少，这可能会影响沉积物的碳和氮循环。稀有类群在FMP干扰下持续存在，而丰富的分类群更容易受到FMP干扰，表明丰富的分类单元对FMP干扰的敏感性更高。尽管随机过程支配着整个微生物群落的组装，丰富和稀有种群的组装机制对FMP干扰的反应明显不同。确定性过程的相对贡献通过丰富种群中增强的同质选择得到加强，而在FMP干扰下的稀有人群中显着下降。此外，FMP大大降低了网络的复杂性，放松了共存关系，并增加了负相关。稀有物种在重塑复杂的微生物相互作用和共存网络以响应FMP干扰中起着重要作用。这项研究拓宽了我们的视野，可以全面评估FMPs在水生环境中的生态效应，以制定进一步的政策控制。
