Functional Diversity and Performance of Ciliated Marine Invertebrate Larvae: Measuring and Modeling Larval Swimming, Feeding and Hydrodynamic Signaling

许多海洋生物，包括贻贝、牡蛎和藤壶，有一个浮游（漂流）的幼虫阶段和一个定居（移动的较少）的底栖成虫阶段。这些生物的成虫将大量幼虫释放到水柱中，幼虫在水柱中发育和生长，并且通常在定居并变成成虫之前分散很长距离。幼虫在水柱中的生存和运输以及幼虫寻找合适栖息地定居的能力塑造了成虫种群的丰度和分布。所有这些因素都受到个体幼虫与周围流体相互作用的显著影响。然而，目前的知识，幼虫流体相互作用，特别是在个人层面上，是稀缺的。该项目将对幼虫-流体相互作用进行最先进的观察和建模研究。该项目为本科生提供了实践培训的机会。这个高度跨学科的项目的研究结果将被纳入以探究为基础的本科课程材料，这些材料将在课堂上教授和评估，并通过数字图书馆公开提供。个体幼虫与周围液体之间的相互作用显著影响了水柱中的生存和运输。这些相互作用的例子包括：1）产生用于运动和颗粒捕获的水流，2）通过最小化流体动力学信号来降低捕食风险，以及3）响应于流体运动（例如在沉降期间的近底湍流）来快速调整游泳模式。了解这些关键的幼虫-流体相互作用需要在精细的空间和时间尺度上进行观测，因为幼虫尺寸小，粘性衰减快。虽然幼虫的整体形态是高度多样化的，但在分类学群体之间有共同的形状，例如软体动物幼虫和海胆的“武装形态”，幼虫使用长纤毛的延伸来进食和游泳。目前还不清楚形态如何影响幼虫-流体相互作用。该项目旨在通过应用高速，高分辨率的微粒子图像测速（microPIV）和计算流体动力学（CFD）建模来量化和机械地检查幼虫-流体相互作用，以填补这些知识空白。本计画针对三组问题：（1）具有相似整体形态的纤毛虫幼虫，其细尺度的幼虫-流体交互作用有何不同？这些差异的生态后果是什么？(2)幼虫对周围液体的影响变化有多快？(3)microPIV作为一种在相关尺度下观察自由游动的幼虫的方法有哪些局限性？为了解决这些问题，将对3对具有武装幼虫的相关物种进行一系列microPIV观察。假设是，尽管总体形状相似，但幼虫-流体相互作用在不同物种之间存在差异，并且在发现幼虫的环境条件下幼虫表现达到峰值。通过比较这些研究物种之间的幼虫-流体相互作用，通过个体发育以及在不同温度和粘度下，将实现假设检验。将获得的观测数据与理论流体动力学模型和CFD模型进行比较，以建立对幼虫如何在其身体周围移动水及其产生的信号的机械理解。

Many marine organisms, including mussels, oysters, and barnacles, have a planktonic (drifting) larval stage and a sedentary (less mobile) bottom-dwelling adult stage. The adults of these organisms release a large number of larvae into the water column, where the larvae develop and grow and often, disperse long distances before settling and changing into adult forms. Larval survival and transport in the water column and larval ability in finding suitable habitat for settlement shape the abundance and distribution of the adult population. All these factors are significantly influenced by the interactions between individual larva and its surrounding fluid. However, current knowledge of larval-fluid interactions, especially at the individual level, is scarce. This project will carry out state-of-the-art observational and modeling studies of larval-fluid interactions. This project provides hands-on training opportunities for undergraduate students. Findings from this highly interdisciplinary project will be incorporated to inquiry-based undergraduate curriculum material that will be taught and evaluated in classrooms and made publicly available through digital libraries.Interactions between individual larva and its surrounding fluid significantly impact survival and transport in the water column. Examples of these interactions include: 1) generating currents for movement and particle capture, 2) reducing predation risk through minimizing the hydrodynamic signals, and 3) rapidly adjusting swimming patterns in response to fluid movements, such as near-bottom turbulence during settlement. Understanding these key larval-fluid interactions requires observations at fine spatial and temporal scales due to small larval size and rapid viscous decay. Although the overall morphology of larvae is highly diverse there are common shapes shared between taxonomic groups, such as the "armed morphology" of larval molluscs and echinoids whereby larvae use long ciliated extensions for feeding and swimming. It is unclear how morphology influences larval-fluid interactions. This project aims at filling in these knowledge gaps by applying high speed, high resolution micro Particle Image Velocimetry (microPIV) and computational fluid dynamics (CFD) modeling to quantify and mechanistically examine larval-fluid interactions. This project addresses three groups of questions: (1) How do fine-scale larval-fluid interactions differ between ciliated larvae with similar overall morphology? What are the ecological consequences of these differences? (2) How rapidly can larvae vary their influences on surrounding fluid? (3) What are the limitations of microPIV as a way to observe freely swimming larvae at the relevant scale? To address these questions, a series of microPIV observations will be conducted on 3 pairs of related species that have armed larvae. The hypothesis is that despite similarity in overall shape, larval-fluid interactions differ between species and larval performance peaks at ambient condition that the larvae are found. Hypothesis testing will be achieved through comparing the larval-fluid interactions between these studied species through ontogeny and at different temperatures and viscosities. The obtained observational data will be compared against theoretical hydrodynamic models and CFD models to build a mechanistic understanding of how larvae move water around their bodies and the resulting signals.