The Hydrodynamics of Phytoplankton Removal in Benthic Boundary Layers by Filter-Feeding Bivalves

本文对双壳类软体动物悬浮进食湍流边界层中颗粒去除的流体力学进行了实验研究。这项研究的动机是需要获得，在各种流动条件下，准确估计这些动物从水柱中去除浮游植物生物量的速率。目前尚不清楚某一双壳类动物种群的颗粒去除率如何与实验室实验中测量的单个动物的抽吸率有关，甚至不清楚在不同于自然条件下测量的种群颗粒去除率。斯坦福大学工程学院将提供补充资金，以促进复杂水槽的建设。在实验室水槽中，对“模型软体动物”（各种泵送装置）上的速度和浓度（溶质和颗粒）场进行广泛测量，将用于测试两个相互关联的假设：(1)近床流体动力学影响悬浮颗粒（包括浮游植物）从水柱流向滤食双壳类的通量，从而决定了滤食双壳类是否能够控制上覆水柱浮游植物生物量。(2)双壳类动物的取食流改变了河床附近的水流特性，特别是颗粒的垂直混合速率，从而决定了底栖滤食性动物何时能够控制浮游植物的数量。为了确保拟议的工作与河口系统的直接相关性，实验计划将与美国地质勘探局的科学家密切合作，研究旧金山湾的悬浮食性双壳类软体动物。

This is an experimental study of the fluid mechanics of particle removal in turbulent boundary layer by suspension feeding bivalve mollusks. The study is motivated by the need to obtain, for a variety of flow conditions, accurate estimates of the rate at which these animals remove phytoplankton biomass from the water column. It is not clear at present how particle removal rates of a given population of bivalves should be related to pumping rates measured for single animals in laboratory experiments, or even particle removal rates measured for populations under conditions different from those found in nature. Stanford's School of Engineering will provide supplemental funds to facilitate the construction of the sophisticated flume. Extensive measurements of velocity and concentration (solutes and particles) fields over "model mollusks" (various pumping arrangements) in the laboratory flume will be used to test two interrelated hypotheses: (1) Near-bed hydrodynamics influence the flux of suspended particles (including phytoplankton) from the water column to filter-feeding bivalves, and thereby determine whether or not filter-feeding bivalves can control phytoplankton biomass in the overlying water column. (2) Bivalve feeding currents modify flow properties near the bed, particularly rates of vertical mixing of particles, and thereby play a role in determining when benthic filter feeders can control phytoplankton populations. In order to assure the direct relevance of the proposed work to estuarine systems, the experimental program will be carried out in close collaboration with USGS scientistsV studying suspension-feeding bivalve mollusks resident in San Francisco Bay.