Cai Shujie, Zhou Xiao, Liu Yao, Tong Zhuyin, Xu Chao, Qu Liyin, Li Penghui, Xiao Wupeng, Guo Weidong, Huang Bangqin
State Key Laboratory of Marine Environmental Science, Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, Xiamen University, Xiamen 361102, China; College of the Environment and Ecology, Xiamen University, Xiamen 361102, China.
State Key Laboratory of Marine Environmental Science, Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, Xiamen University, Xiamen 361102, China; College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China.
Water Res. 2025 Sep 15;284:123996. doi: 10.1016/j.watres.2025.123996. Epub 2025 Jun 9.
River plumes substantially influence dissolved organic matter (DOM) composition and microbial community structure, but the mechanisms linking DOM molecular traits to microbial interactions in these dynamic systems remain poorly understood. We investigated DOM-microbe interactions in the Pearl River plume using high-resolution biogeochemical surveys in the northern South China Sea. By integrating optical, mass spectrometric, and 16S rRNA gene sequencing analyses, we traced DOM molecular composition and bacterial community responses along a salinity gradient. Riverine and local biological inputs enriched bio-labile DOM (BLDOM) in plume waters, which in turn enhanced DOM biochemical transformations and intensified the molecular specificity of bacteria-DOM associations. The enrichment of BLDOM was associated with intensified microbial competition and a shift toward r-strategists with higher ribosomal RNA gene operon (rrn) copy numbers and narrower habitat niche breadths. This pattern supports and extends the "Hunger Games" hypothesis by demonstrating that DOM bioavailability, rather than just inorganic nutrients, acts as a key driver of microbial competition and cooperation in dynamic coastal environments. The dominance of r-strategists in plume waters, characterized by rapid growth and efficient utilization of BLDOM, accelerated DOM turnover and promoted the transformation of bioavailable compounds into more refractory forms, thereby positioning river plumes as hotspots for coastal carbon sequestration. These findings provide new insights into the mechanistic links between DOM dynamics, microbial adaptation strategies, and carbon cycling in coastal ecosystems.
河羽对溶解有机物（DOM）的组成和微生物群落结构有重大影响，但在这些动态系统中，将DOM分子特征与微生物相互作用联系起来的机制仍知之甚少。我们利用南海北部的高分辨率生物地球化学调查，研究了珠江河羽中的DOM-微生物相互作用。通过整合光学、质谱和16S rRNA基因测序分析，我们追踪了沿盐度梯度的DOM分子组成和细菌群落反应。河流和当地生物输入使河羽水体中的生物易降解DOM（BLDOM）富集，这反过来又增强了DOM的生化转化，并强化了细菌与DOM关联的分子特异性。BLDOM的富集与微生物竞争加剧以及向具有更高核糖体RNA基因操纵子（rrn）拷贝数和更窄生境生态位宽度的r策略者转变有关。这一模式支持并扩展了“饥饿游戏”假说，表明DOM的生物可利用性而非仅仅是无机营养物，是动态沿海环境中微生物竞争与合作的关键驱动因素。河羽水体中以快速生长和有效利用BLDOM为特征的r策略者占主导地位，加速了DOM的周转，并促进了生物可利用化合物向更难降解形式的转化，从而使河羽成为沿海碳固存的热点区域。这些发现为沿海生态系统中DOM动态、微生物适应策略和碳循环之间的机制联系提供了新的见解。
