贻贝养殖重构浮游细菌的群落结构与功能

Mussel aquaculture restructures the community structure and function of planktonic bacteria

摘要:

目的 浮游细菌对海洋生态系统健康至关重要，但贻贝养殖如何影响海洋浮游微生物群落尚不明确。本研究旨在探讨贻贝养殖活动对海洋浮游细菌群落结构、多样性及群落组装机制的影响。方法 于2024年夏季在浙江嵊泗贻贝养殖区及外围水域采集68个水样，基于16S rRNA基因扩增子测序数据与环境因子进行综合分析。结果 养殖区内颗粒附着型细菌(particle-attached bacteria, PAB)的α多样性显著降低，而自由生活型细菌(free-living bacteria, FLB)的α多样性虽无显著变化，但其β多样性及系统发育结构发生显著改变。随机森林分析识别出假单胞菌目(Pseudomonadales)与蛭弧菌科(Bdellovibrionaceae)为养殖区内的指示微生物，其群落变化可能与养殖活动导致的有机物输入、营养结构改变等因素密切相关。功能预测显示，养殖区内细菌介导的氮循环功能(特别是硝化作用与好氧氨氧化)显著增强，碳循环以还原性乙酰辅酶A途径为主导，而产甲烷功能受到抑制。微生物群落组装过程在养殖区内由确定性过程(如异质选择)主导，而养殖区外则以随机性过程为主。结论 本研究系统揭示了贻贝养殖在重塑微生物群落结构、功能与群落构建机制方面的重要影响，为评估海水养殖的生态效应提供了理论与数据支撑。

Abstract:

Objective Planktonic bacteria are essential for marine ecosystem health, yet how mussel aquaculture influences planktonic microbial communities remains unclear. This study aims to clarify the effects of mussel aquaculture on the community structure, diversity, and assembly mechanisms of marine planktonic bacteria.Methods Sixty-eight water samples were collected from a mussel aquaculture area and surrounding areas in Shengsi, Zhejiang, during summer 2024. Integrated analyses of 16S rRNA gene amplicon sequencing data and environmental factors were performed.Results The alpha diversity of particle-attached bacteria (PAB) significantly reduced in the aquaculture area, whereas free-living bacteria (FLB) showed no significant change in alpha diversity but exhibited clear shifts in beta diversity and phylogenetic structure. Random forest analysis identified Pseudomonadales and Bdellovibrionaceae as indicator taxa within the aquaculture area, and their changes might be associated with organic matter inputs and altered nutrient conditions. Functional prediction indicated enhanced nitrogen cycling (especially nitrification and aerobic ammonia oxidation) and a shift toward reductive acetogenesis in carbon cycling, alongside suppressed methanogenesis in the aquaculture area. Microbial community assembly was governed mainly by deterministic processes (e.g., heterogeneous selection) in the aquaculture area but by stochastic processes in surrounding waters.Conclusion This study demonstrates that mussel aquaculture can reconfigure the structures, functions, and assembly mechanisms of planktonic bacterial communities, providing insights for ecological impact assessment of mariculture.