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

这个项目将研究浮游动物的行为在产生对海洋结构的反应中的聚集体中的作用。重点放在薄层上，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。其目的是量化桡足类动物对薄层关键属性的阈值响应。在实验室环境中成功地创造了一个受控的、定义明确的薄层，使得能够对浮游生物的运动模式进行定量比较，以响应精细的生物-化学-物理特征。这种特别设计的设备在自然产生的应变率、密度梯度和浮游植物渗出物浓度水平上创建了流动梯度，从而模拟了这种精细海洋特征的基本特性。建议的处理方法的一个独特特点是，通过单独呈现线索，可以评估线索之间的聚集和交互作用的主导线索。建议的实验设计隔离了1.单独线索、组合线索和空间分离的组合线索的影响，2.浮游动物的大小，以及3.薄层中可口的与有毒的浮游植物物种的影响。该项目还将评估桡足类饱足度在浮游生物对薄层线索的阈值敏感度中的作用。在受控良好的环境中观察和量化浮游动物行为的能力，使行为和结构之间有了直接的联系。目前解决这一问题的方法是有限的，因为技术上无法在海洋中进行必要规模的采样。为了从实验室研究扩大到现场行为，将使用基于个体的模型来检查浮游动物种群对海洋结构的浮游动物行为反应的实验室数据。用测量的流场数据参数化的数学模型将被用来再现与物理化学海洋特征有关的浮游动物的同时观测(与Tim Cowles、Mark Benfield、Carin Ashian和Malinda Sutor合作)。因此，精细尺度浮游动物的行为将与它们在海洋中的场分布有关。广泛的影响：浮游动物行为反应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是重要的。拟议的研究将有助于我们了解环境变化对受管理的海洋生物资源(如幼鲑鱼和其他小型中上层鱼类)猎物的分布和可获得性的影响，从而对渔业管理有价值。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界带来了创新的工具，并为原位成像仪器的开发做出了贡献。这项提议也代表了Gerogia Tech和NOAA渔业之间通过安德鲁·莱辛的参与进行的新合作，安德鲁·莱辛实际上是一名合作伙伴。参与这个项目的学生将体验到丰富的跨学科研究环境。在水生化学和水力机械信号领域的现有NSF IGERT和REU计划范围内，这一培训将通过持续的教育努力得到进一步加强。

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.