Phycosphere microbial succession patterns and assembly mechanisms in a marine dinoflagellate bloom

Jin Zhou, Guo-Fu Chen, Ke-Zhen Ying, Hui Jin, Jun-Ting Song, Zhong-Hua Cai
2019 Applied and Environmental Microbiology  
Given the ecological significance of microorganisms in algal blooming events, it is critical to understand the mechanisms regarding their distribution under different conditions. We tested the hypothesis that microbial community succession is strongly associated to algal bloom stages, and that the assembly mechanisms are co-controlled by deterministic and stochastic processes. Community structures and underlying ecological processes of microbial populations (attached and free-living bacteria)
more » ... three algal bloom stages (pre-, during-, and post-bloom) over a complete dinoflagellate Scrippsiella trochoidea bloom were investigated. Both attached and free-living taxa had a strong response to the bloom event, and the latter was more sensitive than the former. The contribution of environmental parameters to microbial variability was 40.2%. Interaction analysis showed that complex positive or negative correlation networks exist in phycosphere microbes. These relationships were the potential drivers of mutualist and competitive interactions that impacted bacterial succession. Null model analysis showed that the attached bacterial community primarily exhibited deterministic processes at pre- and during-bloom stages, while dispersal-related processes contributed to a greater extent at the post-bloom stage. In the free-living bacterial community, homogeneous selection and dispersal limitation dominated in the initial phase, which gave way to more deterministic processes at the two later stages. Relative contribution analyses further demonstrated that the community turnover of attached bacteria was mainly driven by environmental selection, while stochastic factors had partial effects on the assembly of free-living bacteria. Taken together, this data demonstrated that a robust link exists between bacterioplankton community structure and bloom progression, and phycosphere microbial succession trajectories are co-governed by both deterministic and random processes. IMPORTANCE Disentangling the mechanisms shaping bacterioplankton communities during a marine ecological event is a core concern for ecologists. Harmful algal bloom (HAB) is a typical ecological disaster, and its formation is significantly influenced by algae-bacteria interactions. Microbial community shifts during the HAB process are relatively well known. However, the assembly processes of microbial communities in a HAB are not fully understood, especially the relative influences of deterministic and stochastic processes. We therefore analyzed the relative contributions of deterministic and stochastic processes during a HAB event. Both free-living and attached bacterial groups had a dramatic response to the HAB, and the relative importance of determinism versus stochasticity varied between the two bacterial groups at various bloom stages. Environmental factors and biotic interactions were the main drivers impacting on the microbial shift process. Our results strengthen the understanding of the ecological mechanisms controlling microbial community patterns during the HAB process.
doi:10.1128/aem.00349-19 pmid:31126952 pmcid:PMC6643250 fatcat:7e5dnhof6fhaxbwv4r4bdd7z6y