The responses of prokaryotic communities to the algal blooms from the Pearl River estuary

Abstract

Algal blooms are severe ecological disasters in the marine environment, affecting the biogeochemical cycles substantially. It is critical to explore how the prokaryotic community responds to the dynamics of algal blooms in the marine environment. The shifts in prokaryotic communities during the algal blooms have been extensively investigated, while the interactions and assembly mechanisms of prokaryotic communities are still incompletely understood. We conducted nutrient addition cultivations for the brackish water from the Pearl River estuary to simulate the algal bloom process and monitored the prokaryotic community compositions over forty days. Results showed evident differences between blooming and after-bloom stages of prokaryotic communities in diversity and taxonomic compositions. Bacillus, Gimesiaceae, and Fibrobacteraceae were dominant before the cultivation. Mesoflavibacter, Rhodobacteraceae, and Acinetobacter were accumulated in the blooming stage. Acinetobacter, Comamonadaceae, and Gimesia were enriched in the after-blooming stage, while Mesoflavibacter, Rhodobacteraceae, and Acinetobacter were active during the whole blooming period. Co-occurrence networks analysis showed that prokaryotic interactions were predominantly driven by positive relationships that impacted the algal blooming fates. Rhodobacteraceae, Flavobacteriaceae, Winogradskyella, and Pseudomonas are the keystone groups of the prokaryotic communities in the blooming stage network, while Marinobacter, Thalassobaculum, Actinobacteria, Flavobacterium, and Rhodobacteraceae are the keystone groups of the after-bloom stage network. Functional prediction by FAPROTAX showed that dissimilatory nitrate reduction increased in the after-bloom stage. Our study revealed the dynamic of the prokaryotic communities and the characteristics of their co-occurrent profiles, which shed light on revealing the potential functions of prokaryotic behaviors during estuarine algal blooming events.