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所消耗，现在普遍认为海洋浮游原生生物是浮游植物最重要的食草动物，原生生物的食草作用会从根本上影响浮游植物的生物量和在海洋中的分布。原生生物可以暂时变得非常丰富（每升高达数万个），并且可以像浮游植物一样快速生长，这使它们具有调节浮游植物种群的巨大潜力。原生生物适应选择性地以生长最快的浮游植物为食，并减少后生浮游动物的捕食，这应增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性。与大型后生浮游动物如桡足类相比，原生动物选择性摄食和躲避捕食者的形态和行为适应知之甚少。研究员将利用高速摄影技术，在三维空间中研究自由游动的浮游原生生物的选择性摄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。为了获得一个机械的理解，他们还将进行经验数据驱动，现实再现计算流体动力学（CFD）模拟原生生物施加的流场。结果将被用来测试的假设，多样性和灵活性，推进形态有利于原生动物实现复杂的游泳行为和感官知觉能力，使其适应选择性进食和捕食者回避。 这些能力也可能是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。两名研究生将参加该项目，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精密光学系统方面的培训。在浮游生物生态学的小规模生物物理相互作用领域进行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将根据其结果构建一个易于遵循的互动在线学习模块，并将通过其网站向教育工作者和广大公众提供原生生物行为的视频剪辑。

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.