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

哲水蚤类桡足类非稳态摄食电流的数值研究本研究项目将解决的问题，“为什么有两种时间类型的产生摄食电流之间的食草性哲水蚤桡足类”？也就是说，当动物每次开始移动时都必须克服周围水的惯性时，为什么它们表现出开/关模式，产生不稳定的流动？我们将首先在现场直接观察喂养动物。然后，我们将在实验室中以3D方式观察它们，以定义（1）摄食电流的结构，以及（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。该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。实验将在箭牌海洋科学中心进行为期两周的停留，在那里我们将观察Calanus pacificus和Rhincalanus nasutus在原位和实验室。结果将是关于切换喂养电流开/关的频率的数据，以及关于动物周围水流的结构和时间变化的数据。我们还将研究活动模式的哲水蚤桡足类从海洋关闭萨凡纳，GA，在不同的食物密度。生成的所有数据集将不断用于WHOI的CFD模拟设计。我们期望能找到证据，证明生活在营养稀环境中的哲水蚤桡足类存在不同的生存策略。交替产生摄食电流的策略可以基于低超重、大体型和低食物浓度之间的折衷。这将与高超重、恒定馈电电流、大传感范围和中等食物密度的策略形成对比。浮游桡足类生活在各种各样的环境中，食物丰富度往往受到严重限制。到目前为止，很少有研究已经解决了桡足类的行为剧目，以适应这种减少的食物供应。我们的研究旨在提高我们对桡足类摄食行为的理解，通过研究经验自由游动的哲水蚤，产生不同种类的不稳定的开/关摄食电流，然后将新获得的结果与我们迄今为止对稳定摄食电流的了解进行比较。该项目将支持一名年轻的物理科学家与三名有成就的高级生物海洋科学家进行综合性跨学科研究。此外，我们亦设有多个网页，介绍浮游动物生态学、海洋及淡水等，吸引不少市民浏览。这些网页将有助鼓励青少年学习自然科学。数据档案及模拟结果亦会上载于我们的网站（http：//www.uwm.edu/cnjrs）供公众查阅。我们将在科学文献中传播我们的结果。两名本科生将与G。-A. Paffenhofer将在项目过程中与PI团队互动。

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? We will first directly observe feeding animals in situ. Then, we 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. We 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. We 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. Our 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. Our well-visited web sites on zooplankton ecology, marine and fresh-water, will serve to stimulate young persons to pursue the natural sciences. Data files and simulation results will also be uploaded onto our website of (http://www.uwm.edu/~jrs) for public access. We will disseminate our 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.