Active sinking particles: sessile suspension feeders significantly alter the flow and transport to sinking aggregates
Active sinking particles: sessile suspension feeders significantly alter the flow and transport to sinking aggregates
复制标题
主动下沉颗粒：固着悬浮给料器显着改变了下沉骨料的流动和运输
DOI：
10.1098/rsif.2022.0537
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发表时间：
2023
影响因子：
3.9
通讯作者：
Prakash, Manu
中科院分区：
文献类型：
--
作者：
Krishnamurthy, Deepak;Pepper, Rachel;Prakash, Manu
生物聚集体的下沉或沉积在海洋固碳和废水处理厂的垂直物质通量方面发挥着关键作用。在这两种情况下，下沉的聚集体是“活跃的”，因为它们是生物热点，并且被包括细菌和固着原生生物在内的微生物密集地定殖，其中一些产生摄食电流。然而，这些馈电电流的下沉率，轨迹和质量转移到这些“活性下沉颗粒”的效果以前没有被研究过。在这里，我们使用一种新型无标度垂直跟踪显微镜（又名重力机; Krishnamurthyet al.2020Nat.方法17，1040-1051（doi：10.1038/s41592-020-0924-7））跟踪附着原生生物（Vorticella convallaria）的下沉聚集体（琼脂球）模型，在长距离下沉的同时测量局部流量。我们发现这种活动是由于附加的V。convallaria引起显着的变化，以动态的方式聚集体周围的流动和重塑质量传输边界层。此外，我们发现，活动介导的本地流沿着与下沉修改的遭遇和羽横截面的聚集，并诱导持续的聚集旋转。总的来说，我们的工作表明，生物活动在塑造聚集体周围的近场流具有潜在的重要影响聚集体的命运和材料通量的重要作用。
Sinking or sedimentation of biological aggregates plays a critical role in carbon sequestration in the ocean and in vertical material fluxes in wastewater treatment plants. In both these contexts, the sinking aggregates are ‘active’, since they are biological hot-spots and are densely colonized by microorganisms including bacteria and sessile protists, some of which generate feeding currents. However, the effect of these feeding currents on the sinking rates, trajectories and mass transfer to these ‘active sinking particles’ has not previously been studied. Here, we use a novel scale-free vertical tracking microscope (a.k.a. gravity machine; Krishnamurthyet al.2020Nat. Methods17, 1040–1051 (doi:10.1038/s41592-020-0924-7)) to follow model sinking aggregates (agar spheres) with attached protists (Vorticella convallaria), sinking over long distances while simultaneously measuring local flows. We find that activity due to attachedV. convallariacauses significant changes to the flow around aggregates in a dynamic manner and reshapes mass transport boundary layers. Further, we find that activity-mediated local flows along with sinking modify the encounter and plume cross-sections of the aggregate and induce sustained aggregate rotations. Overall, our work shows the important role of biological activity in shaping the near-field flows around aggregates with potentially important effects on aggregate fate and material fluxes.