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，现在人们普遍认为海洋浮游原生生物是浮游植物最重要的食性动物，原生生物的觅食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(每升高达数万)，并且可以像浮游植物一样快速生长，这给了它们调节浮游植物种群的巨大潜力。原生生物适应选择性地摄食增长最快的浮游植物物种，并减少后生浮游动物的捕食，应加强浮游植物生长和放牧之间的耦合，从而促进浮游生态系统的稳定。与大型后生浮游动物如桡足类相比，原生动物对选择性取食和躲避捕食者的形态和行为适应相对较少。PI将使用高速视频在三维中研究自由游泳浮游原生动物的选择性取食行为和捕食者回避行为的细节。在相同的条件下，他们将使用时间分辨率立体微粒子图像测速系统(MicroPIV)测量单个自由游泳原生生物施加的流场。为了从机理上理解，他们还将进行经验数据驱动的、再现现实的计算流体力学(CFD)模拟原生物体施加的流场。研究结果将被用来检验这一假说，即推进形态的多样性和灵活性有助于原生动物实现复杂的游泳行为和感官感知能力，使它们适合选择性摄食和躲避捕食者。这些能力也可以作为原生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。两名研究生将参加这个项目，并将接受浮游生物生态学和海洋生物学、理论/计算/实验浮游生物流体力学以及建立和使用尖端光学系统方面的培训。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知识，这种培训将有助于他们为开展跨学科研究做准备。PIS将根据其结果构建一个易于跟踪和互动的在线学习模块，并将通过其网站向教育工作者和广大公众提供有关原生动物行为的视频剪辑。

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.