Fluid mechanical and chemical cues in Thin Layers: Effects of scale and individual behavior

该项目将研究浮游动物的行为在海洋结构下产生聚集的作用。研究的重点是薄层，这是一种广泛分布的海洋现象，可能是浮游生物斑块的组织元素。目的是量化桡足动物对薄层关键特性的阈值反应。在实验室环境中成功创建一个受控的定义良好的薄层，可以对浮游生物的运动模式进行定量比较，以响应精细尺度的生物-化学-物理特征。这个特别设计的装置在自然发生的应变速率、密度梯度和浮游植物渗出物浓度水平上产生水流梯度，从而模仿这种精细尺度海洋特征的基本特性。所提出的治疗方法的一个独特之处在于，通过单独呈现线索，可以评估线索聚集和相互作用的主导线索。提出的实验设计隔离了1的影响。个体线索，组合线索，和空间分离的组合线索，2。浮游动物的大小；薄层中美味与有毒的浮游植物种类。该项目还将评估桡足类饱足在浮游生物对薄层线索的阈值敏感性中的作用。在良好控制的环境中观察和量化浮游动物行为的能力使行为和结构之间的直接联系成为可能。目前解决这个问题的方法是有限的，因为技术上无法在海洋中取样到必要的尺度。为了将实验室研究扩大到原位行为，浮游动物对海洋结构的行为反应的实验室数据将使用基于个体的模型对浮游动物种群进行检查。用实测的现场数据参数化的数学模型将用于重现与海洋物理化学特征相关的浮游动物的同时观测（与Tim Cowles、Mark Benfield、Carin Ashjian和Malinda Sutor合作）。因此，精细尺度的浮游动物行为将与它们在海洋中的场分布有关。更广泛的影响：浮游动物行为反应背后的生物和物理机制对于解释和预测海洋生态系统的能量和物质循环以及生产力非常重要。拟议的研究将通过提高我们对环境变化对受管理的海洋生物资源（如幼年鲑鱼和其他小型远洋鱼类）猎物分布和可用性的影响的理解，对渔业管理有价值。这项研究依赖于生物学和流体力学之间的跨学科合作。佐治亚理工学院的持续合作为海洋学社区带来了创新工具，并为原位成像的仪器开发做出了贡献。这项提案还代表了乔治亚理工学院与美国国家海洋和大气管理局渔业部门之间的一项新的合作，Andrew Leising是事实上的共同负责人。参与该项目的学生将体验到丰富的跨学科研究环境。在现有的NSF IGERT和REU在水生化学和流体机械信号领域的项目中，将通过正在进行的教育努力进一步加强这种培训。

This project will study the role of zooplankton behavior in producing aggregations in response to ocean structure. The focus is on thin layers, a wide-spread oceanic phenomenon that may serve as an organizing element of plankton patchiness. The objective is to quantify copepod threshold responses to key properties of thin layers. The successful creation of a controlled well-defined thin layer in a laboratory setting enables a quantitative comparison of kinematic patterns of plankton in response to fine-scale biological-chemical-physical features. The specially-designed apparatus creates flow gradients at naturally-occurring strain rate, density gradient, and phytoplankton exudate concentration levels, thus mimicking the essential properties of this fine-scale oceanic feature. A unique feature of the proposed treatments is that by presenting cues separately, the dominant cue for aggregation and interactions among cues can be assessed. The proposed experimental design isolates the effect of 1. individual cues, combined cues, and combined cues that are spatially separated, 2. zooplankton size, and 3. palatable vs. toxic phytoplankton species in the thin layer. The project will also evaluate the role of copepod satiation in the threshold sensitivity of plankton to thin layer cues. The ability to observe andquantify zooplankton behavior within a well-controlled environment enables a direct link between behavior and structure. Current approaches to this problem are limited because of a technological inability to sample in the ocean at the necessary scales. To scale up from the laboratory studies to in situ behavior, the laboratory data on zooplankton behavioral responses to oceanic structure will be examined for zooplankton populations using an individual-based model. The mathematical model parameterized with measured current field data will be used to reproduce the concurrent observations (in collaboration with Tim Cowles, Mark Benfield, Carin Ashjian, and Malinda Sutor) of zooplankton associated with physical-chemical oceanic features can be predicted using. Thus, fine-scale zooplankton behavior will be connected to their field distribution with respect to features in the ocean.Broader Impacts: The biological and physical mechanisms underlying zooplankton behavioral responses are important to interpret and predict energy and material cycling and productivity of ocean ecosystems. The proposed research will be valuable to fisheries management by advancing our understanding of the impact of environmental change on the distribution and availability of prey items for managed living marine resources, such as juvenile salmon and other small pelagic fish. This research relies on an interdisciplinary collaboration between biology and fluid mechanics. The continued collaboration at Georgia Tech brings innovative tools to the oceanographic community and contributes to instrument development for in situ imaging. This proposal also represents a new collaboration between Gerogia Tech and NOAA Fisheries through the participation of Andrew Leising, who is a de facto Co-PI. The students involved in this project will experience a rich interdisciplinary research environment. This training will be further enhanced by on-going educational efforts, within existing NSF IGERT and REU programs in the area of aquatic chemical and hydromechanical signaling.