Abstract：
Understanding the rapid responses of marine microbiomes to environmental disturbances is paramount for supporting early assessments of harm to high-value ecosystems, such as coral reefs. Yet, management guidelines aimed at protecting aquatic life from environmental pollution remain exclusively defined for organisms at higher trophic levels. In this study, 16S rRNA gene amplicon sequencing was applied in conjunction with propidium monoazide for cell-viability assessment as a sensitive tool to determine taxon- and community-level changes in a seawater microbial community under copper (Cu) exposure. Bayesian model averaging was used to establish concentration-response relationships to evaluate the effects of copper on microbial composition, diversity, and richness for the purpose of estimating microbiome Hazard Concentration (mHCx) values. Predicted mHC5 values at which a 5 % change in microbial composition, diversity, and richness occurred were 1.05, 0.72, and 0.38 μg Cu L-1, respectively. Threshold indicator taxa analysis was applied across the copper concentrations to identify taxon-specific change points for decreasing taxa. These change points were then used to generate a Prokaryotic Sensitivity Distribution (PSD), from which mHCxdec values were derived for copper, suitable for the protection of 99, 95, 90, and 80 % of the marine microbiome. The mHC5dec guideline value of 0.61 μg Cu L-1, protective of 95 % of the marine microbial community, was lower than the equivalent Australian water quality guideline value based on eukaryotic organisms at higher trophic levels. This suggests that marine microbial communities might be more vulnerable, highlighting potential insufficiencies in their protection against copper pollution. The mHCx values proposed here provide approaches to quantitatively assess the effects of contaminants on microbial communities towards the inclusion of prokaryotes in future water quality guidelines.
摘要：
了解海洋微生物对环境干扰的快速反应对于支持早期评估对高价值生态系统的危害至关重要，比如珊瑚礁。然而，旨在保护水生生物免受环境污染的管理准则仍然专门针对较高营养级的生物。在这项研究中,16SrRNA基因扩增子测序与单叠氮丙啶一起用于细胞活力评估，作为确定铜（Cu）暴露下海水微生物群落中分类单元和群落水平变化的敏感工具。贝叶斯模型平均用于建立浓度-响应关系，以评估铜对微生物组成的影响，多样性,和丰富度，用于估计微生物组危害浓度(mHCx)值。微生物组成变化5%的预测mHC5值，多样性,和丰富度分别为1.05、0.72和0.38μgCuL-1。在铜浓度上应用阈值指示类群分析，以确定用于降低类群的类群特异性变化点。然后将这些变化点用于产生原核敏感性分布（PSD），从中得出铜的mHCxdec值，适用于保护99、95、90和80％的海洋微生物组。mHC5dec指导值为0.61μgCuL-1，保护95%的海洋微生物群落，低于基于较高营养水平的真核生物的等效澳大利亚水质指导值。这表明海洋微生物群落可能更脆弱，强调了它们在防止铜污染方面的潜在不足。此处提出的mHCx值提供了定量评估污染物对微生物群落影响的方法，以将原核生物纳入未来的水质准则。
