Viscous constraints on zooplankton approach and interaction

在水中游泳的生物需要接近悬浮颗粒进行各种生命过程，如进食，交配，受精和寻找有利的栖息地。这项研究的重点是浮游生物，尽管它们的体积很小，但由于数量丰富，它们在海洋生态中发挥着巨大的作用。例如，浮游植物通过将阳光转化为有机物质，提供了食物网的基础，有机物质进一步转移到食物链，主要是通过吃浮游植物的浮游动物。浮游动物在微米到毫米尺度上的流体动力学主要由粘性决定，严重限制了它们接近其他颗粒的能力。试图接近较小的食物颗粒是困难的粘性流动，往往推动食物颗粒离开。然而，浮游动物在交配过程中也会接近类似大小的颗粒，以及在卵受精或探索新栖息地时更大的颗粒。研究的目的是了解粘性流体动力学对浮游生物接近悬浮颗粒的一般限制，以及这些限制如何决定生物的形式和功能。研究结果将增加我们对浮游生物如何进食、繁殖和传播到新栖息地的理解。该项目还将通过研究生和本科生的研究培训来加强工程教育，一个推广计划将把我们的研究成果传达给当地的高中生。虽然粘性流体动力学约束推进和微生物的游泳机制的形式的方式是很好的赞赏，这项研究扩展了我们的理解粘性流体动力学的影响，包括限制的方法，这是作为或更重要的比游泳的许多生命过程。为了推断如何流体动力学约束的方法确定生物的形式和行为，该研究使用数值研究，流动可视化和动态缩放的实验，以调查一系列的游泳者的几何形状，推进方法，目标颗粒大小和方法的策略，以确定哪些能够在粘性约束的存在下接近。研究结果将用于分析文献中报道的各种类型生物体的接近观察结果，以了解粘性约束何时决定这些生物体的生物形式。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

Organisms that swim in water need to approach suspended particles for a variety of life processes, such as feeding, mating, fertilization, and finding favorable habitats. This research focuses on plankton, which despite their small size play an outsize role in ocean ecology due to their numerical abundance. For example, phytoplankton provide the base of the food web by converting sunlight into organic matter, which is transferred further up to the food chain, primarily by zooplankton which eat the phytoplankton. Hydrodynamics at the micro- to millimeter scales of zooplankton is dominated by viscosity, and severely constrains their ability to approach other particles. Attempts to approach smaller food particles are made difficult by viscous flows that tend to push the food particle away. However, zooplankton also approach similar size particles during mating, as well as larger particles during egg fertilization or when exploring new habitats. The goal of the research is to understand what general constraints viscous hydrodynamics place on the approach of plankton to suspended particles and how those constraints determine biological form and function. The results will increase our understanding of how plankton eat, reproduce, and spread to new habitats. The project will also enhance engineering education through graduate and undergraduate research training, and an outreach program will communicate our research results to local high school students. While the way that viscous hydrodynamics constrains propulsion and the form of swimming mechanisms of microorganisms is well appreciated, this research extends our understanding of the implications of viscous hydrodynamics to include constraints on approach which is as or more important than swimming for many life processes. To deduce how hydrodynamic constraints on approach determine biological form and behavior, the research uses numerical studies, flow visualization, and dynamically scaled experiments to investigate a range of swimmer geometries, propulsion methods, target particle sizes, and approach strategies to identify which enable close approach in the presence of viscous constraints. The results will be used to analyze observations of approach of various types of organisms reported in the literature to understand when viscous constraints determine the biological form of those organisms.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.