Multifaceted aspects of synchrony between bacterioplankton and protists. temporal patterns of microbes

Bacteria and protists undergo high temporal turnover. Here, we compared the temporal patterns of bacterioplankton and protists in three different habitats for four years (2014-2017) in Lake Tovel, a cold-water lake. This lake showed a marked temperature increase in 2017 linked to altered precipitation patterns. We investigated if shifts in microbial composition reflected this change and if shifts occurred at the same time and to the same extent.Furthermore, we tested the concept of hydrological year emphasising the ecological effect of water renewal on communities for its explanatory power of community changes. Microbe diversity was assessed by Illumina sequencing of the V3–V4 hypervariable region of 16S rRNA and 18S rRNA, and we applied co-inertia analysis and asymmetric eigenvector mapsmodelling to infer synchrony and temporal patterns of bacterioplankton and protists.Considering community composition, microbes were invariably in synchrony across sites and indicated a gradient in composition linked to decreasing precipitation; however when considering temporal patterns, the extent of synchrony was reduced because of different shapes of slow temporal patterns of microbes. Shape differences were linked to different sensibility of microbes towards an ecosystem change, partially linked to increasing water transparency and temperature and decreasing dissolved oxygen. As generally noted, seasonal patterns of microbes were linked to seasonally varying environmental variables. Our advanced statistical approach outlined the multifaceted aspect of synchrony when linked to community composition and temporal patterns.

细菌与原生生物（protists）的时间周转速率较高。本研究针对冷水湖托维尔湖（Lake Tovel）内的三种不同生境，开展了为期四年（2014-2017年）的监测工作，对比了浮游细菌（bacterioplankton）与原生生物的时间动态模式。2017年该湖出现显著升温，且这一现象与降水格局改变存在关联。我们探究了两个核心科学问题：其一，微生物群落组成的变化是否响应这一环境扰动；其二，这类变化是否同步发生且变化幅度一致。此外，本研究检验了“水文年”（hydrological year）这一概念，旨在评估水体更新对群落的生态效应，以及该概念解释群落变化的能力。本研究通过对16S rRNA与18S rRNA的V3–V4高变区进行Illumina测序，对微生物多样性进行了定量测定；同时采用共惯量分析（co-inertia analysis）与不对称特征向量映射建模（asymmetric eigenvector maps modelling），以推断浮游细菌与原生生物的群落同步性及时间动态模式。针对群落组成的分析结果显示，各采样点的微生物群落始终保持同步，且群落组成梯度与降水减少存在显著关联；但就时间动态模式而言，由于不同微生物类群的缓慢时间变化形态存在差异，群落间的同步性有所降低。这类形态差异与微生物对生态系统变化的敏感性差异密切相关，其中部分敏感性差异可归因于水体透明度升高、水温上升及溶解氧（dissolved oxygen）下降。正如既往研究普遍报道的那样，微生物的季节动态模式与随季节波动的环境变量显著相关。本研究采用的先进统计方法，揭示了同步性在与群落组成及时间动态模式耦合时所呈现的多维度特性。