Short and intensive microbial dynamics during Akashiwo sanguinea (Dinophyta) blooms

Abstract

To understand micro-ecosystem changes during harmful algal blooms (HABs), we examined the variability of micro-environments and microbiome (virus to plankton) through short and intensive investigation during Akashiwo sanguinea blooms in Jangmok coastal waters of South Korea by metagenomics. The exudation of extracellular polymeric substances (EPS) by A. sanguinea markedly changed bio-geochemical cycles (in particular phosphorus and carbon sources). In A. sanguinea-associatedbacteria communities, Rickettsia rhipicephali and Polaribacter marinivivus positively affect the HABs, while Amylibacter ulvae, Mesonia algae, and Luminiphilus syltensis negatively affect the HABs. An endoparasitic Amoebophrya sp., may importantly control bloom dynamics, as increase in their abundance lagged the HABs decline. In the dsDNA viruses, Pandoraviridae increased following increases in the HABs peaks, but Phycodnaviridae might not infect A. sanguinea. Thus, A. sanguinea blooms dramatically change the micro-ecosystem through their efficient autotrophic processes and exudation of EPS, followed by changes in the microbiome involving species-specific viruses, bacteria, and parasitoids.