Collaborative Research: Numerical Study of the Unsteady Feeding Currents in Calanoid Copepods

鱿鱼类桡足类非定常摄食流的数值研究本研究项目将解决“为什么食草鱿鱼类桡足类会有两种产生摄食流的时间类型”这一问题。也就是说，为什么动物在每次开始移动时都必须克服周围水的惯性，却表现出开/关的模式，从而产生不稳定的流动？研究人员将首先在现场直接观察动物的进食情况。然后，他们将在实验室中以3D方式观察它们，以定义(1)进食电流的结构，(2)不同食物制度下的时间模式。该数据库包括观察到的动物的形状和大小，将用于使用计算流体动力学（CFD）进行模拟。研究小组由一名应用数学家/环境流体动力学家（Jiang， WHOI），一名生物海洋学家（Paffenhofer， SKIO）和两名实验海洋生物学家（Strickler和Janssen， UWM）组成。实验将在Wrigley海洋科学中心进行为期两周的停留，在那里我们将在现场和实验室中观察Calanus pacificus和Rhincalanus nasutus。结果将是关于喂食电流开关频率的数据，以及动物周围水流的结构和时间变化的数据。研究人员还将研究来自乔治亚州萨凡纳附近海域的鱿鱼类桡足类动物在不同食物密度下的活动模式。生成的所有数据集将不断用于WHOI的CFD模拟设计。研究人员希望能找到证据，证明在营养稀薄的环境中，鱿鱼类桡足类动物存在不同的生存策略。交替产生喂食电流的策略可能是基于低超重、大体型和低食物浓度之间的折衷。这将与高超重、恒定喂食电流、大感应范围和中等食物密度的策略形成对比。智力优势浮游桡足类动物生活在多变的环境中，通常食物丰富程度严重受限。到目前为止，很少有研究涉及桡足动物的行为适应这种减少的食物供应。本研究旨在通过实验研究自由游动的角鲨类，以提高我们对桡足动物摄食行为的认识，并将新获得的结果与我们迄今为止对稳定摄食流的认识进行比较。更广泛的影响该项目将支持一位年轻的物理科学家与三位有成就的资深海洋生物科学家进行跨学科的综合研究。这些网站的主题包括浮游动物生态学、海洋及淡水等，点击率很高，有助鼓励年青人研习自然科学。研究人员将在科学文献中传播研究结果。两名本科生将与G. a .一起在Skidaway工作。在项目过程中，帕芬霍夫将与项目项目总监团队进行互动。

Numerical Study of the Unsteady Feeding Current in Calanoid Copepods This research project will address the question, "Why are there two temporal types of generating feeding currents among herbivorous calanoid copepods"? That is, why do animals show an on/off pattern, creating an unsteady flow, when they have to overcome the inertia of the surrounding water every time they start moving? The investigators will first directly observe feeding animals in situ. Then, they will observe them in 3D in the laboratory to define (1) the structures of the feeding currents, and (2), the temporal patterns under different food regimes. The database, which includes the shapes and sizes of the animals observed, will be used for simulations using computational fluid dynamics (CFD). The research team consists of an applied mathematician/environmental fluid dynamicist (Jiang, WHOI), a biological oceanographer (Paffenhofer, SKIO), and two experimental marine biologists (Strickler and Janssen, UWM). Experiments will be conducted during a two-week stay at the Wrigley Marine Science Center where we will observe Calanus pacificus and Rhincalanus nasutus in situ and in the laboratory. The results will be data on the frequencies of switching the feeding current on/off, and on the structures and temporal changes of the water flow around the animals. The investigators will also study the activity patterns of calanoid copepods from the ocean off Savannah, GA, under different food densities. All the data sets generated will be constantly used to design the simulations in CFD at WHOI. The investigators expect to find evidence that there exist different survival strategies among calanoid copepods living in nutritionally dilute environments. The strategy to alternate the generation of a feeding current may be based on a compromise between low excess weight, large body size, and low food concentrations. This would contrast to the strategy of high excess weight, constant feeding current, large sensing range, and moderate food density. Intellectual Merits Planktonic copepods live in environments of varying and often severely limiting food abundances. So far few if any studies have addressed the adaptations of copepod behavioral repertoires to this diminished food availability. This study is designed to improve our understanding of copepod feeding behavior by studying empirically free-swimming calanoids, which produce unsteady on/off feeding currents of different kinds, and then compare the newly gained results with our knowledge to date about the steady feeding currents. Broader Impact The project will support the research efforts of a young, physically oriented scientist in a well-integrated interdisciplinary study with three accomplished senior biological ocean scientists. The PIs well-visited web sites on zooplankton ecology, marine and fresh-water, will serve to stimulate young persons to pursue the natural sciences. The investigators will disseminate the results in the scientific literature. Two undergraduate students will be working at Skidaway with G. -A. Paffenhofer and will interact with the team of PIs during the course of the project. .