In Situ and Theoretical Analysis of Zooplankton Patch Dynamics

浮游动物斑块动态的原位和理论分析浮游动物斑块是一个众所周知的现象。虽然斑块空间结构及其与环境变化的相关性已经得到了很好的描述，并且已经提出了理论解释，但由于技术限制，迄今为止还不可能直接测量斑块的形成和持续。研究人员将进行重点实地和模型研究，以量化科德角湾东部密集桡足类斑块的结构、动力学和控制机制。他们将采用数值模拟、高分辨率生物和物理测绘以及现场行为观察相结合的方法，直接验证斑块形成的三步过程：1)向上游动增强近水面丰度；2)表面收敛和向上游动速度的增加进一步增强了丰度；3)收敛区的高丰度增加了邻居间的检测率，从而增加了聚集行为。在实地项目中，将在潮汐周期的不同阶段进行测量，以检查由于潮汐驱动的汇聚而形成的斑块。在收敛消散后，对斑块持久性的测量将表明生物聚集行为在维持斑块中的作用。桡足动物游泳行为的各种组成部分的直接现场观测将与环境（CTD，荧光，衰减，下行光）和流体速度数据一起使用，以确定斑块形成模型的参数值。会聚流中的斑块形成将结合两种方法进行建模：1)该地区的高分辨率三维数值模型，以量化潮汐和潮下流和会聚；2)包含会聚流的斑块形成和群集过程模型。这些计算结果将与三维贴片结构随时间变化的实际测量结果进行比较。这项工作将为浮游动物斑块形成和维持机制的研究提供新的思路。

Davis 9818661In-situ and Theoretical Analysis of Zooplankton Patch DynamicsZooplankton patchiness is a well-known phenomenon. Although patch spatial structure and its corre-lation with environmental variation has been well described, and theoretical explanations for it have been proposed, direct measurement of how patches form and persist has not been possible to date because of technological limitations. The investigators will conduct a focused field and modeling study to quantify the struc-ture, dynamics, and controlling mechanisms of dense copepod patches in eastern Cape Cod Bay. Using a combination of numerical modeling, high resolution biological and physical mapping, and in-situ behav-ioral observations, they will directly test the hypothesis that the patches form in a three-step process: 1) upward swimming enhances near-surface abundance, 2) surface convergence together with increased up-ward swimming rate further enhances abundance, and 3) high abundance in the convergence zone increases interneighbor detection rates which lead to increased aggregation behavior. During the field program, mea-surements will be made during different phases of the tidal cycle to examine formation of the patches due to the tidally driven convergence. Measurements of patch persistence after the convergence has dissipated will be indicative of the role of biological aggregation behavior in maintaining the patches. Direct in-situ observations of various components of copepod swimming behavior will be used together with environmental (CTD, fluorescence, attenuation, downwelling light) and fluid velocity data to determine parameter values for patch formation models. Patch formation in convergent flow will be modeled using a combination of two approaches: 1) high resolution 3-D numerical models of the region to quantify tidal and subtidal flow and convergence and 2) process models of patch formation and swarming that incorporate convergent flows. These calculations will be compared with the actual measurements of how the 3-D patch structure varies over time. The proposed work will shed new light on mechanisms of patch formation and maintenance in zooplankton.