Collaborative Research: Linking Propulsive Morphology, Swimming Behavior and Sensory Perception by Marine Planktonic Protists to their Trophic Roles within Marine Food Webs

生物海洋学的核心问题之一是了解调节海洋中浮游植物生物量和分布的过程。大多数浮游植物的命运是被食草动物吃掉，目前人们普遍认为，海洋浮游生物原生生物是浮游植物最重要的食草动物，原生生物的放牧可以从根本上影响海洋浮游植物的生物量和分布。原生生物可以暂时变得非常丰富（每升多达数万），并且几乎可以像浮游植物一样快速生长，这使它们具有很大的潜力来调节浮游植物的数量。原生生物选择性地以生长最快的浮游植物为食，并减少后生动物对浮游动物的捕食，这将增强浮游植物生长与放牧之间的耦合，从而促进浮游生态系统的稳定。与大型的后生浮游动物（如桡足类）相比，我们对原生生物在选择进食和躲避捕食者方面的形态和行为适应知之甚少。pi将使用高速视频在三维空间中研究自由游动的浮游原生生物的选择摄食行为和捕食者躲避行为的细节。在相同的条件下，他们将使用时间分辨立体微粒子图像测速（microPIV）系统测量单个自由游动的原生生物施加的流场。为了获得机理上的理解，他们还将对原生生物施加的流场进行经验数据驱动的、再现现实的计算流体动力学（CFD）模拟。研究结果将用于验证一种假设，即推进形态的多样性和灵活性有助于原生生物实现复杂的游泳行为和感觉知觉能力，使其适应选择性进食和捕食者躲避。这些能力也可能是原生生物生物多样性的重要驱动力，表现为各种大小、形状、推进形态和运动模式。两名研究生将参与该项目，并将接受浮游生物生态学和海洋生物学的培训；在理论/计算/实验浮游生物流体力学；在设置和使用复杂的光学系统。在浮游生物生态学中进行小规模生物-物理相互作用领域的研究需要跨学科的知识，这种培训将有利于他们进行跨学科研究的准备。pi将根据他们的研究结果构建一个易于操作和互动的在线学习模块，并将通过他们的网站向教育工作者和广大公众提供原生行为的视频剪辑。

One of the central issues in biological oceanography is to understand the processes that regulate the biomass and distribution of phytoplankton in the ocean. The fate of most phytoplankton is to be consumed by grazers, and it is now generally accepted that marine planktonic protists are the most important grazers on phytoplankton, and that grazing by protists can fundamentally affect phytoplankton biomass and distribution in the ocean. Protists can become temporarily very abundant (up to tens of thousands per liter) and can grow nearly as rapidly as phytoplankton do, which gives them great potential to regulate phytoplankton populations. Adaptations by protists to feed selectively on the fastest growing species of phytoplankton and to reduce predation by metazoan zooplankton should enhance the coupling between phytoplankton growth and grazing, and therefore promote planktonic ecosystem stability. Compared to larger metazoan zooplankton such as copepods, relatively little is known about the morphological and behavioral adaptations in protists for selective feeding and predator avoidance. The PIs will study details of selective feeding behavior and predator avoidance behavior of free-swimming planktonic protists in 3-dimension using high-speed video. Under the same conditions, they will measure flow fields imposed by individual free-swimming protists using a time-resolving stereo micro-particle image velocimetry (microPIV) system. To gain a mechanistic understanding, they will also conduct empirical data-driven, reality-reproducing computational fluid dynamics (CFD) simulations of the protist-imposed flow fields. The results will be used to test the hypothesis that diversity and flexibility in propulsive morphology facilitates protists to achieve sophisticated swimming behaviors and sensory perception capabilities that adapt them for selective feeding and predator avoidance. These capabilities may also serve as important driving forces for protistan biodiversity, represented by various sizes, shapes, propulsive morphologies and motility patterns. Two graduate students will participate in this project and will receive training in plankton ecology and marine biology; in theoretical/computational/experimental plankton fluid mechanics; and in setting up and using sophisticated optical systems. Conducting research in the field of small-scale biological-physical interactions in plankton ecology requires interdisciplinary knowledge, and this training will benefit their preparation for conducting interdisciplinary research. The PIs will construct an easily-followed and interactive online learning module based on their results, and will make video clips of protistan behavior available to educators and the public at large through their web sites.