Growth rates of marine prokaryotes are extremely diverse, even among closely related taxa

Marine prokaryotes play crucial roles in ocean’s biogeochemical cycles, being their contribution largely determined by their growth rates. To improve our understanding of microbial communities’ dynamics and structure, we estimated prokaryotic growth rates at high resolution, the amplicon sequence variant (ASV) level, using manipulation experiments in each of the four astronomical seasons with different treatments that reduced limiting growth factors such as predators, nutrient availability, viruses and light. Single-ASV-based growth rate calculations showed a continuous range of values, reaching almost 10 day-1. Mean growth rates per treatment increased as limiting factors were removed, and changed seasonally. Results revealed significant variability in growth rate distribution patterns even within closely related ASVs, and with no general taxonomic coherence observed after removal of each growth limiting factor. Reduction of these factors showed that most responsive ASVs were rare, and formed a pool of taxa with the potential to rapidly respond to environmental changes. In essence, our results highlight the significance of rare-responsive taxa often overlooked in whole-community studies and suggest high dynamism in marine microbial communities with a strong capacity to adapt to changing environments