Community assembly of bacteria and archaea in coastal waters governed by contrasting mechanisms: A seasonal perspective

Abstract

Marine planktonic bacteria and archaea commonly exhibit pronounced seasonal succession in community composition. But the existence of seasonality in their assembly processes and between-domain differences in underlying mechanism are largely unassessed. Using a high-coverage sampling strategy (including single sample for each station during four cruises in different seasons), 16S rRNA gene sequencing, and null models, we investigated seasonal patterns in the processes governing spatial turnover of bacteria and archaea in surface coastal waters across a sampling grid over ~300 km in the East China Sea. We found that archaea only bloomed in prokaryotic communities during autumn and winter cruises. Seasonality mostly overwhelmed spatial variability in the compositions of both domains. Bacterial and archaeal communities were dominantly governed by deterministic and stochastic assembly processes, respectively, in autumn cruise, probably due to the differences in niche breadths (bacteria < archaea) and relative abundance (bacteria > archaea). Stochasticity dominated assembly mechanisms of both domains but was driven by distinct processes in winter cruise. Determinism-dominated assembly mechanisms of bacteria rebounded in spring and summer cruises, reflecting seasonal variability in bacterial community assembly. This could be attributed to seasonal changes in bacterial niche breadths and habitat heterogeneity across the study area. There were seasonal changes in environmental factors mediating the determinism-stochasticity balance of bacterial community assembly, holding a probability of the existence of unmeasured mediators. Our results suggest contrasting assembly mechanisms of bacteria and archaea in terms of determinism-vs.-stochasticity pattern and its seasonality, highlighting the importance of seasonal perspective on microbial community assembly in marine ecosystems.

Diversity Distribution, Driving Factors and Assembly Mechanisms of Free-Living and Particle-Associated Bacterial Communities at a Subtropical Marginal Sea

“…By contrast, studies in the Chinese coastal bays and the East China Sea showed that stochastic processes outweighed deterministic processes in microbial community assembly [41,42]. In addition, previous research in bacterioplankton assembly also took into consideration the influence of seasonality [43,44]. These studies suggest that microbial community assembly processes are not conserved between different marine ecosystems and highlight the need for biome-specific investigations.…”

Homogeneous environmental selection dominates microbial community assembly in the oligotrophic South Pacific Gyre

“…However, in the East China Sea the relative importance of stochastic and deterministic processes varied seasonally, as deterministic processes became more influential during spring and summer (Wang et al, 2020). These studies suggest that microbial community assembly processes are not conserved between different marine ecosystems, and highlight the need for biome-specific investigations.…”

Habitats and seasons differentiate the assembly of bacterial communities along a trophic gradient of freshwater lakes

“…Additionally, the range of environmental conditions in which a species can exist (i.e. niche breadth) plays a crucial role in influencing the relative importance of stochasticity and determinism (Wu et al., 2018); and aquatic bacterial niche breadth varies seasonally (Wang et al., 2020). We thus expect that there may be seasonal variability in the community assembly of PBC and SBC.…”