Microbial community resident in the phycosphere have been discussed to be tightly associated with algae and can promote or inhibit algal growth during algal blooms. Many studies have been able to describe the microbial communities structure and dynamic variation during the succession of a bloom event with regards to different algal host. However, these studies represent isolated cases with different spatiotemporal distribution.Whether there is an obligate selection relationship between the algal host and certain microbial species still remain unclear. Here, the phycosphere microbial communities of P. donghaiense obtained from several independent events were subject to in-depth analyses to reveal the dominant and the rare taxa shared by these samples. Furthermore, the multiple co-occurrence networks of microbial communities were analyzed. Our study reveals that, in addition to the high abundance of Flavobacteriales and Rhodobacterales, which demonstrated elevated centrality parameter scores (high eccentricity, high betweenness centrality, etc.) in the microbial network in the histological analyses, Camplyobacterales and Burkholderiales, etc. also exhibited high centrality parameters at lower abundance, suggesting their potential as keystone taxons in dinoflagellate bloom research.It is noteworthy that the fitting of centrality parameters to network nodes revealed a tendency whereby node communities with high centrality parameters did not exhibit significant overlap with node communities with high relative abundance. In this study, the structure of the co-occurrence network of the microbiome during algal blooms was combined with basic histological parameters with the objective of identifying key species in the phycosphere and exploring the relationship between abundance and topological features.
 

harmful algal blooms (HABs), microbial community, co-occurrence network