Multifaceted aspects of synchrony between bacterioplankton and protists

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.