In the right place, at the right time: the integration of bacteria into the Plankton Ecology Group model

Background Planktonic microbial communities have critical impacts on the
pelagic food web and water quality status in freshwater ecosystems, yet no
general model of bacterial community assembly linked to higher trophic
levels and hydrodynamics has been assessed. In this study, we utilized a
two-year survey of planktonic communities from bacteria to zooplankton on
three freshwater reservoirs to investigate their spatiotemporal dynamics.
Result We observed the site-specific presence and microdiversification of
bacteria in lacustrine and riverine environments, as well as in deep
hypolimnia. Moreover, we determined recurrent bacterial seasonal patterns
driven by both biotic and abiotic conditions, which could be integrated
into the well-known Phytoplankton Ecology Group (PEG) model describing
primarily the seasonalities of larger plankton groups. Importantly,
bacteria with different ecological potentials showed finely coordinated
successions affiliated with four seasonal phases, including the spring
bloom dominated by fast-growing opportunists, the clear-water phase
associated with oligotrophic ultramicrobacteria, the summer phase
characterized by phytoplankton bloom-associated bacteria, and the
fall/winter phase driven by decay-specialists.   Conclusion Our
findings elucidate the principles driving the spatiotemporal microbial
community distribution in freshwater ecosystems. We suggest an extension
to the original PEG model by integrating recurrent bacterial seasonal
trends.