The nutrient-rich effluent from wastewater treatment plants (WWTPs) constitutes a significant disturbance to coastal microbial communities, which in turn affect ecosystem functioning. However, little is known about how such disturbance could affect the community's stability, an important knowledge gap for predicting community response to future disturbances. Here, we examined dynamics of coastal sediment microbial communities with and without a history of WWTP's disturbances (named H1 and H0 hereafter) after simulated nutrient input loading at the low level (5 mg L⁻¹ NH₄⁺-N and 0.5 mg L⁻¹ PO₄^3--P) or high level (50 mg L⁻¹ NH₄⁺-N and 5.0 mg L⁻¹ PO₄^3--P) for 28 days. H0 community was highly sensitive to both low and high nutrient loading, showing a faster community turnover than H1 community. In contrast, H1 community was more efficient in nutrient removal. To explain it, we found that H1 community constituted more abundant and diversified r-strategists, known to be copiotrophic and fast in growth and reproduction, than H0 community. As nutrient was gradually consumed, both communities showed a succession of decreasing r-strategists. Accordingly, there was a decrease in community average ribosomal RNA operon (rrn) copy number, a recently established functional trait of r-strategists. Remarkably, the average rrn copy number of H0 communities was strongly correlated with NH₄⁺-N (R² = 0.515, P = 0.009 for low nutrient loading; R² = 0.749, P = 0.001 for high nutrient loading) and PO₄^3--P (R² = 0.378, P = 0.034 for low nutrient loading; R² = 0.772, P = 0.001 for high nutrient loading) concentrations, while that of H1 communities was only correlated with NH₄⁺-N at high nutrient loading (R² = 0.864, P = 0.001). Our results reveal the potential of using rrn copy number to evaluate the community sensitivity to nutrient disturbances, but community's historical contingency need to be taken in account.

废水处理厂（WWTP）富含营养的废水构成了对沿海微生物群落的重大干扰，进而影响了生态系统的功能。但是，人们对这种干扰如何影响社区的稳定性知之甚少，这是预测社区应对未来干扰的重要知识缺口。在这里，我们考察沿海沉积物微生物群落的动力学有和没有在低电平（5毫克的L模拟养分输入负荷后WWTP的干扰（称为H1和H0下文）的历史^-1 NH ₄ ⁺ -N和0.5毫克的L ^{- 1} PO ₄ ^3- -P）或高水平（50 mg L ^-1 NH ₄ ⁺ -N和5.0 mg L^-1 PO ₄ ^3- -P）28天。H0社区对低养分和高养分含量都高度敏感，显示出比H1社区更快的社区更新。相比之下，H1群落在去除营养方面更有效。为了解释这一点，我们发现H1社区比H0社区构成了更多丰富和多样化的r策略家，众所周知，他是同营养型的，并且生长和繁殖较快。随着营养物质的逐渐消耗，这两个社区都显示出不断减少的r策略家。因此，社区平均核糖体RNA操纵子（rrn）拷贝数减少了，这是r策略家最近建立的功能特征。值得注意的是，H0群落的平均rrn拷贝数与NH ₄ ⁺ -N（R²  = 0.515， 对于低养分含量，P = 0.009；R ²  = 0.749， 对于高养分而言，P = 0.001）和PO ₄ ^3- -P（ 对于低养分而言 ，R ² = 0.378，P = 0.034；对于高养分而言，R ²  = 0.772，P  = 0.001）浓度，而在高养分含量下，H1群落的氮素含量仅与NH ₄ ⁺ -N相关（R ²  = 0.864，P  = 0.001）。我们的结果揭示了使用rrn拷贝数评估社区对养分干扰的敏感性的潜力，但需要考虑社区的历史偶然性。