Relative Influence of Turbulence and Waves on Larval Behavior

本研究将探讨来自不同栖息地的蜗牛幼虫如何在湍流和表面重力波中对流体力学线索作出反应。湍流和波浪是沿海流动的共同特征，可能为幼虫提供行为线索，帮助它们向特定的流动状态或栖息地运输。湍流会导致一些软体动物的幼虫更频繁地下沉，但目前还不清楚它们的探测机制和对波浪的反应。幼虫可以感知空间速度梯度（应变率和涡度）或加速度。湍流和波浪对幼虫尺度流动的影响不同；湍流可以产生较大的应变率和涡度，而波浪可以产生较大的加速度。能够感知多种流动特征的幼虫可能能够区分湍流主导的海岸码头和大陆架波浪主导的地区。在本研究中，幼虫的行为将在几种产生稳定应变率和涡量、简单加速、均匀湍流和湍流加波的复杂流动的装置中进行量化。这些数据将用于发展作为流体动力学函数的幼虫行为的随机模型，并测试关于生态和基于尺寸的行为控制的假设。智力优势：本研究旨在解决幼虫行为和湍流和波浪对生态影响的以下基本问题：1)获得行为信号的新方法。将两相红外粒子成像测速技术应用于多个流动池，在幼虫尺度上研究湍流和波浪的影响。将开发统计协议，将行为观察转化为经验模型，为更复杂的行为与物理循环模型的仔细整合奠定基础。结果将确定影响潮间带和陆架生境物种行为的关键流体特征。2)波浪对行为的影响。许多栖息地受到海浪的影响，甚至受其支配，但迄今为止还没有研究探索海浪提供幼虫行为信号的可能性。这项研究将首次探索幼虫对仅在波浪中存在的大加速度的反应。3)行为在扩散中的作用。底栖生物招募变化的部分原因是由于幼虫对自然环境的反应而导致的扩散的变幻莫测。由于分层、水深、潮汐和风的影响，湍流和波浪在空间上和时间上都有变化。湍流和波浪的小规模症状可能会引起幼虫的行为，从而导致扩散轨迹的差异。这项研究将描述幼虫对流体力学线索的反应，最终可以解释分散和招募的不确定性。4)对自然环境的适应。剪切和加速是潜在的行为信号，可能会因划船、海岸线改造或风暴等人类影响而增强或减弱。如果行为被调整到特定的水流状态，幼虫可能难以适应不断变化的海洋环境。这项工作将有助于评估变化的物理过程对幼虫行为和扩散的潜在生态影响。更广泛的影响：拟议的研究整合了生态学、海洋物理学和最先进的技术，以促进跨学科的研究、教学和基础设施。Gerbi是一名博士后，他的职业生涯将受益于一个高度跨学科项目的指导和经验。一名研究生将进行论文研究，同时获得海洋生态学、流体力学和流量测量技术方面的专业知识。两名本科生将被招募参加NSF RIOS项目和罗格斯大学少数族裔学生的Aresty项目，罗格斯大学的学生将在这个项目的一部分上写一篇毕业论文。本研究结果将被纳入研究生和本科生生物物理相互作用的新课程中。该项目提供了几个机会来改善和扩大幼虫动物园，一个向广大观众提供游动幼虫电影的网络档案馆。PIV和流动箱将完成一个新的浮游生物-流体相互作用实验室，利用罗格斯大学的大量贡献。PIV是罗格斯大学海水水槽设施流量测量能力的宝贵升级。

This study will investigate how snail larvae from distinct habitats respond to fluid-mechanical cues in turbulence and surface gravity waves. Turbulence and waves are common features of coastal flows and may provide larvae with behavior cues that aid transport toward specific flow regimes or habitats. Turbulence induces some mollusk larvae to sink more frequently, but still unknown are the detection mechanism and the response to waves. Larvae may sense spatial velocity gradients (strain rate and vorticity) or acceleration. Larval-scale flows are affected differently by turbulence and waves; turbulence can generate larger strain rates and vorticity whereas waves can generate larger accelerations. Larvae that sense multiple flow characteristics may be able to distinguish between turbulence-dominated coastal embayments and wave-dominated regions of the continental shelf. In this study, larval behaviors will be quantified in several devices that generate steady strain rates and vorticity, simple acceleration, homogeneous turbulence, and complex flow with turbulence plus waves. Data will be used to develop stochastic models of larval behavior as a function of hydrodynamics and to test hypotheses about ecological and size-based controls on behavior.Intellectual Merit: The proposed research addresses the following fundamental aspects of larval behavior and the ecological impacts of turbulence and waves:1) Novel approaches to gain insights on behavioral signaling. Two-phase infrared particle-image velocimetry techniques will be applied in multiple flow tanks to study effects of both turbulence and waves at the scale of larvae. Statistical protocols will be developed for converting behavior observations into empirical models, laying the groundwork for careful integration of more complex behaviors with physical circulation models. Results will identify the key fluid characteristics affecting behavior in species from intertidal and shelf habitats.2) Impact of waves on behavior. Many habitats are influenced or even dominated by waves, yet no study to date has explored the potential for waves to provide a larval behavioral signal. This study will be the first to explore larval response to the large accelerations present only in waves.3) Role of behavior in dispersal. Benthic recruitment variability arises partly from vagaries of dispersal that result from larval responses to the physical environment. Turbulence and waves vary spatially and also temporally due to stratification, water depth, tides, and winds. Small-scale symptoms of turbulence and waves could elicit larval behaviors that contribute to differences in dispersal trajectories. This study will describe larval responses to hydromechanical cues that ultimately could explain uncertainty in dispersal and recruitment.4) Adaptation to physical environments. Shears and acceleration are potential behavior signals that could be enhanced or dampened by human impacts such as boating, shoreline modification, or storms. If behaviors are tuned to specific flow regimes, larvae may have difficulty adapting to changing marine environments. This work will be instrumental in assessing potential ecological impacts of changing physical processes on larval behavior and dispersal.Broader Impacts: The proposed study integrates ecology, ocean physics, and state-of-the-art technology to promote interdisciplinary research, teaching, and infrastructure. Co-PI Gerbi is a postdoctoral associate, and his career will benefit from mentoring and experience on a highly interdisciplinary project. One graduate student will do dissertation research while gaining expertise in marine ecology, fluid mechanics, and flow-measurement technology. Two undergraduates will be recruited to participate through the NSF RIOS program and the Rutgers Aresty program for minority students, and the Rutgers student will do a senior thesis on part of this project. Results of this research will be incorporated into a new course in biological-physical interactions for graduate and undergraduate students. The project offers several opportunities to improve and expand the Larval Zoo, a web archive that provides movies of swimming larvae to a wide audience. The PIV and flow tanks will complete a new Plankton-Fluid Interactions Laboratory, leveraging a substantial contribution from Rutgers. The PIV is an invaluable upgrade to the flow-measurement capabilities of the Rutgers seawater flume facility.