Data for: Measuring community-level functional resistance and community rescue potential under environmental stress

The widely used half maximal inhibitory concentration and related indices, e.g., minimum inhibitory concentration and mutant prevention concentration, are in vitro measures of response of biological or biochemical processes to inhibitor substances. We propose to adapt the above concepts for developing standard measures of functional resistance and rescue of ecological communities under environmental pollution. Specifically, a “half inhibitory concentration” index (IC50) is defined as the concentration at which a pollutant reduces a community-level function to 50% of the baseline state immediately after exposure. A “half community rescue prevention concentration” index (CRPC50) is the concentration at which a pollutant can prevent community-level ecological function from recovering to 50% of the baseline state after a prolonged period of recovery. CRPC50 is supposedly higher than IC50. We performed two experiments with natural aquatic microbial communities and considered respiration rate as a surrogate of whole-community function. The IC50 and CRPC50 of the herbicide glyphosate and the heavy metallic salt copper sulfate were estimated by dose-response curves. One specific finding is that CRPC50 values of glyphosate were typically higher than IC50 by > 2.4 folds, while for copper sulfate the CRPC50 values did not significantly differ from IC50. This suggested that our microbial communities showed little adaptive response to the latter pollutant agent. Standardized measures of functional resistance and community rescue potential such as those proposed in the present study would be comparable across environmental stress agents and study systems, and improve our study of short- and long-term consequences of environmental pollutants for microbial community functioning.

当前广泛应用的半数最大抑制浓度（half maximal inhibitory concentration）及其相关指标，例如最低抑菌浓度（minimum inhibitory concentration）与防突变浓度（mutant prevention concentration），均为表征生物或生化过程对抑制物质响应的体外检测指标。本研究提出将上述概念进行适配，以构建环境污染下生态群落功能抗性与恢复潜力的标准化量化指标。具体而言，‘半数抑制浓度’指数（IC50）被定义为：污染物暴露即刻，可将群落水平功能降至基线状态50%时的污染物浓度。‘半数群落恢复抑制浓度’指数（CRPC50）则为：污染物可使群落水平生态功能在经历长期恢复周期后，仍无法回升至基线状态50%时的污染物浓度。理论上CRPC50应高于IC50。本研究以天然水生微生物群落为对象开展两组实验，并以呼吸速率作为全群落功能的替代表征指标。通过剂量-响应曲线估算了除草剂草甘膦（glyphosate）与重金属盐硫酸铜（copper sulfate）的IC50与CRPC50值。一项核心研究结果显示：草甘膦的CRPC50值通常较IC50高出2.4倍以上，而硫酸铜的CRPC50值与IC50并无显著统计学差异。这表明本研究中的微生物群落对后者（硫酸铜）几乎未表现出适应性响应。本研究提出的这类功能抗性与群落恢复潜力的标准化量化指标，可在不同环境胁迫因子与研究体系间实现横向比较，有助于深化我们对环境污染物影响微生物群落功能的短期与长期效应的研究。