Fontánez Ortiz Marc Alec, De Martini Francesca, Neuer Susanne
School of Life Sciences, Arizona State University, Tempe, AZ 85287, United States.
School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, United States.
ISME Commun. 2025 May 19;5(1):ycaf083. doi: 10.1093/ismeco/ycaf083. eCollection 2025 Jan.
Sinking particles are important conduits of organic carbon from the euphotic zone to the deep ocean, but their origin and community composition are still a matter of investigation. Events in the northwestern Sargasso Sea, such as winter convective mixing, summer stratification, and mesoscale eddies, affect the vertical and temporal composition and abundance of pelagic and particle-attached microorganisms. We sampled the euphotic zone and collected sinking particles using shallow traps near the Bermuda Atlantic Time-series Study site during the spring and summer of 2012 to assess eddy-driven impact on microbial communities. In the spring, we sampled a cyclonic eddy, while in the summer, we targeted both the center and edge of an anticyclonic eddy. Prokaryotic and photoautotrophic (plastid and cyanobacteria) communities were analyzed using V4-V5 amplicons of the 16S rRNA gene. Community and clustering analysis of prokaryotes revealed a clear separation between seawater and particles samples. However, the same was not observed for photoautotrophs. Indicator species analysis showed that small phytoplankton taxa dominated particle communities. Interestingly, differential abundance analyses revealed that the large centric diatom, , generally rare in the oligotrophic Sargasso Sea, was enriched in the photoautotrophic communities of sinking particles collected in the center of the anticyclonic eddy with unusual upwelling due to eddy-wind interactions. We hypothesize that the steady contribution of small-celled phytoplankton to particle flux is punctuated by pulses of production and flux of larger-sized phytoplankton in response to episodic eddy upwelling events and can lead to higher export of particulate organic matter during the summer.
下沉颗粒是有机碳从透光层输送到深海的重要通道，但其来源和群落组成仍有待研究。马尾藻海西北部的一些事件，如冬季对流混合、夏季分层和中尺度涡旋，会影响浮游生物和附着在颗粒上的微生物的垂直和时间组成及丰度。2012年春季和夏季，我们在百慕大大西洋时间序列研究站点附近使用浅水陷阱对透光层进行采样并收集下沉颗粒，以评估涡旋驱动对微生物群落的影响。春季，我们对一个气旋涡进行了采样，而夏季，我们针对一个反气旋涡的中心和边缘进行采样。使用16S rRNA基因的V4 - V5扩增子分析了原核生物和光合自养生物（质体和蓝细菌）群落。原核生物的群落和聚类分析显示海水样本和颗粒样本之间有明显分离。然而，光合自养生物并未观察到同样的情况。指示物种分析表明，小型浮游植物类群在颗粒群落中占主导地位。有趣的是，差异丰度分析显示，大型中心硅藻，这种在贫营养的马尾藻海通常罕见的物种，在反气旋涡中心因涡 - 风相互作用出现异常上升流而收集的下沉颗粒的光合自养群落中富集。我们推测，小型浮游植物对颗粒通量的稳定贡献会因大型浮游植物的生产和通量脉冲而中断，这些脉冲是对间歇性涡旋上升流事件的响应，并且可能导致夏季颗粒有机物质的更高输出。
