Measurements of trajectories and spatial distributions of diatoms (Coscinodiscus spp.) at dissipation scales of turbulence
Measurements of trajectories and spatial distributions of diatoms (Coscinodiscus spp.) at dissipation scales of turbulence
复制标题
湍流耗散尺度下硅藻（Coscinodiscus spp.）的轨迹和空间分布测量
DOI：
10.1007/s00348-021-03240-5
复制
发表时间：
2021
影响因子：
2.4
通讯作者：
Karp-Boss, Lee
中科院分区：
文献类型：
--
作者：
Pujara, Nimish;Du Clos, Kevin T.;Ayres, Stephanie;Variano, Evan A.;Karp-Boss, Lee
摘要硅藻是一种光合微生物，在水生食物网和全球生物地球化学循环中起着重要作用。它们居住在海洋和湖泊的上层，它们与湍流耗散尺度的相互作用控制着各种过程，如养分获取、捕食者相互作用和聚集。细胞与湍流的相互作用也可能改变垂直运动和空间分布。然而，由于难以在实验室中产生与生态相关的流动或在野外跟踪微观细胞，因此对这些相互作用的观察仍然很少。在这里，我们提出了一个实验系统，能够测量在湍流中活硅藻细胞的轨迹和空间分布。小体积湍流槽采用随机强迫约束平均流量，在较高雷诺数下产生均匀的湍流统计量。单个细胞轨迹在三维跟踪与体积粒子成像仪，使用散焦成像的原理结合双针孔孔径掩膜，以获得粒子的位置在三维使用单个相机。我们在两种不同的湍流强度下进行了实验，结果表明，虽然硅藻的均方根速度与示踪粒子相似，但它们的空间分布在耗散尺度上比示踪粒子更强。这种聚集行为令人惊讶，因为硅藻细胞的特征是非常低的斯托克斯数，而且当湍流强度（和耗散率）增加时，聚集会减少。有几种机制可以解释这一结果，包括细胞形状效应和响应环境湍流的细胞密度主动调节。图形抽象
AbstractDiatoms are a group of photosynthetic microorganisms that play important roles in aquatic food webs and global biogeochemical cycles. They reside in the upper layer of oceans and lakes, and their interactions with the dissipation scales of turbulence govern a variety of processes, such as nutrient acquisition, prey–predator interactions, and aggregation. Interactions of cells with turbulence may also alter vertical motions and spatial distributions. However, observations of these interactions remain scarce because of the difficulty of generating ecologically relevant flows in the lab or tracking microscopic cells in the field. Here, we present an experimental system capable of measuring trajectories and spatial distributions of live diatom cells in turbulence. The small-volume turbulence tank uses stochastic forcing to restrict mean flow while producing homogeneous turbulence statistics at relatively high Reynolds number. Individual cell trajectories are tracked in three dimensions with a volumetric particle imager that uses the principle of defocused imaging combined with a double-pinhole aperture mask to obtain particle positions in three dimensions using a single camera. We conducted experiments at two different turbulence intensities and our results show that while root-mean-square velocities of diatoms are similar to those of tracer particles, their spatial distributions indicate enhanced clustering at the dissipation scales in comparison with tracer particles. This clustering behaviour is surprising both because diatom cells are characterised by a very low Stokes number and because clustering decreases when the turbulence intensity (and dissipation rate) increases. Several mechanisms could explain this result, including cell shape effects and active regulation of cell density in response to the ambient turbulence.Graphic abstract
登录
查看更多内容
影响因子：
4.5
作者：
Du Clos, Kevin T.;Karp-Boss, Lee;Gemmell, Brad J.
通讯作者：
Gemmell, Brad J.
使用可现场部署的体积粒子成像仪 (VoPI) 对流体和粒子运动进行拉格朗日测量
DOI：
--
发表时间：
2013
期刊：
影响因子：
--
作者：
I. Tse;E. Variano
通讯作者：
E. Variano
使用潜水全息术测量海洋中浮游生物的分布
DOI：
--
发表时间：
1999
期刊：
影响因子：
--
作者：
E. Malkiel;Omar Alquaddoomi;J. Katz
通讯作者：
J. Katz
硅藻细胞和链的细胞密度（每单位体积的质量）与其大小、生长和营养状况的关系
DOI：
--
发表时间：
2017
期刊：
影响因子：
--
作者：
S. Ayres
通讯作者：
S. Ayres