Diatom red tide significantly drive the changes of microbiome in mariculture ecosystem

Some diatom species cause red tides under eutrophic conditions, but little is known about their impact on the ecological structure of coastal systems. In this study, the effects of diatom red tides on the bacterial and eukaryotic communities in aquaculture systems were analyzed using high-throughput sequencing. The correlation between these communities and environmental factors was also analyzed. Principal coordinate analysis (PCoA) and non-metric multidimensional scaling (NMDS) showed that there were significant differences in the microbiome in red tide ponds and normal ponds (p < .05). The dominant bacterial taxa in red tide and normal ponds were Proteobacteria, Actinobacteria, Cyanobacteria, Bacteroidetes, Verrucomicrobia and Planctomycetes. There were significant differences in the abundance of bacteria genera, such as Planctomyces, Marivita, Synechococcus and Marinobacterium, in red tide ponds and normal ponds (p < .05). Functional predictions showed that red tides affect carbon, nitrogen, sulfur and phosphorus metabolism in ponds. There were significant differences in the dominant eukaryotic genera in red tide ponds and normal ponds (p < .05). Red tide ponds were dominated by Skeletonema, Thalassiosira, and Cyclotella, while Ostreococcus, Hemiselmis, Glycine, and Cryothecomonas were dominant in normal ponds. Canonical correlation analysis (CCA) indicated that pH, DO salinity, nitrate, nitrite, ammonium and phosphate were significantly correlated with microbiomes in red tide and normal ponds. OTU (operational taxonomic unit) network analysis results showed that the dominant OTUs of Thalassiosira and Skeletonema were negatively correlated with most of the dominant OTUs of Proteobacteria, Actinobacteria, Bacteroidetes and Cyanobacteria. The importance of biotic interactions when investigating the link between the microbiome and red tide species has also been highlighted. This study revealed the important influence of a diatom red tides on bacterial and eukaryotic communities, and provided new insights into the impact of diatom red tides on mariculture ecosystems.