[A-OS17] Marine microbial ecology

[AOS17-P05] Temporal Variability and Ecological Interaction of Planktonic Microbial Communities in A Coastal Aquaculture Area

*Qian Liu^1,2, Jian Wang¹, Mengmeng Tong², Mingyan Lai¹ (1.Second Institute of Oceanography, Ministry of Natural Resources, P. R. China, 2.Zhejiang University)

Keywords:Phytoplankton community, Prokaryotic community, Metatranscriptome, Phytoplankton-prokaryote interaction, Coastal aquaculture

Marine planktonic communities are pivotal for ecosystem functions, but sensitive to environmental changes. The coastal aquaculture plays a crucial role in carbon and nutrient transformation, mostly driven by planktonic communities, yet their temporal variations and interactions remain poorly understood. Here, we sampled seawater over 1.5 years in a mussel aquaculture on the subtropical coast, and used amplicon and metatranscriptomic sequencing to investigate mechanisms driving variations in prokaryotic and phytoplankton communities. Both communities showed distinct variations in composition, diversity and structure, with prokaryotes more susceptible to environmental changes. Network analyses revealed complex intraspecific interactions as a result of niche partition in November, indicating resilience. Intense interspecific interactions were observed between Flavobacteriales/Rhodobacterales and Dinophyta from May to July. The linkage between SAR11 and Dinophyta varied temporally due to diversified SAR11 subclades. Prokaryotic transcription revealed increased gene expression related to phytoplankton derived molecule metabolism, and biosynthesis of phytohormones and vitamins during summer. Rhodobacterales, SAR11 and Flavobacteriales contributed significantly to the transcription. Cryptophyta were key groups involved in prokaryote and phytoplankton interactions at the transcription level. Our findings highlight the impact of environmental fluctuations and biotic interactions on planktonic communities, shedding light on fundamental mechanisms governing stability and vulnerability of planktonic communities to natural and anthropogenic perturbations.