Metabarcoding analysis of microbiome dynamics during a Phaeocystis globosa bloom in the Beibu Gulf, China.

Phaeocystis globosa is an ecologically important haptophyte that can form harmful algal blooms (HABs). In this study, we used 16S rDNA V3-V4 amplicon sequencing data to explore the ecological mechanisms underlying a P. globosa bloom in the Beibu Gulf, China. Using field samples collected from three time points of a bloom, we observed a distinct succession in the bacteria, archaea and phytoplankton community composition throughout the bloom. We also observed temporal variation in response to the bloom at the nucleotide level, which supports a previously underappreciated amount of intragroup variation in the niches taken up by microbes during HABs. We developed a preliminary model for the development and progression of the P. globosa bloom using the spatial-temporal dynamics of P. globosa and the bacteria, archaea, phytoplankton and environmental variables. We also identified microbes with putative interactions with P. globosa during the bloom by identifying microbes correlated with P. globosa in interaction networks, identifying particle-associated microbes and exploring the P. globosa colony microbiome using sequences from whole P. globosa colonies collected during the bloom. This study revealed novel insight into the development of P. globosa HABs and many testable hypotheses that will guide future research on the mechanisms of P. globosa HABs.