EU-US ECOHAB. EC-NSF Cooperative Activity in Environmental Research: In Situ Holographic Measurements of Particle Distributions and Small Scale Turbulence in Thin Layers

该项目是根据欧盟-美国有害藻类生态和海洋学合作活动提交的。美国PIS将与来自法国、爱尔兰、西班牙和英国的同事一起研究有害藻华(HAB)集中的薄层的物理和生物学。在欧洲，严重的问题是养殖的贝类受到由甲藻属产生的腹泻性贝毒(DSP)毒素的污染。最近发现了具有较高牙藻浓度的薄层的存在，但这些信息是零星的，因为这些层可以在任何深度存在，而且由于标准仪器的采样困难。就Dinophysis而言，浓度不仅取决于营养，还取决于物理、生命周期和行为之间的相互作用。这项研究将确定导致牙藻在薄层中建立、维持和种群动态的水动力(如局部水流结构、湍流、层结、小回旋和跃层)、生物(如生长、营养和死亡)和化学环境。现场测试将在加利西亚(西班牙西北部)的里亚斯、法国大西洋海岸的河口羽流地带和爱尔兰西南部的海湾的各种水动力条件下进行。所有这些都是贝类生产区，有因受到DSP毒素污染而关闭收获的历史。约翰斯·霍普金斯研究小组将专注于小规模的生物物理和粒子-粒子相互作用。通过部署一个水下全息摄像机，再加上数字全息电影照相术，他们将观察和测量在10毫米到10厘米的关键尺度上发生的过程和相互作用。自动化的数据分析工具将使研究人员能够在各种条件下处理一个大型数据库，这些数据库将被用来对Dinophysis的行为进行参数化。结果将包括：i.不同类别颗粒的空间分布和尺寸分布。检测到大于10 mm的颗粒，并可以在大于30 mm的颗粒中定义形状。二、同一物种内部以及物种之间的最近邻距离(NNS)，包括捕食者和猎物；I.样品体积内的瞬时三维速度分布，用于计算局部速度、应变率、涡量、耗散率和湍流强度；浮游植物在其本地环境中的游泳行为(速度、轨迹、方向)；V.直接观察浮游植物的行为、取食和觅食；基于当地物理和生物参数的浓度、NN和行为的条件统计；智力价值：在理解不同浮游植物物种(包括Dinophysis)种群动态方面的进展，需要详细了解它们的就地浓度、行为和生物物理相互作用。该项目将在海洋中部署一种新的但经过验证/开发的技术，以获得关于甲藻与其当地生物物理环境相互作用的详细和独特的见解。这些结果将阐明影响含牙根真菌的薄层形成和维持的过程。更广泛的影响。社会经济问题：赤潮对沿海海域的健康、旅游业、渔业和粮食生产造成不利影响，导致渔业关闭、疾病甚至死亡。该项目将获得必要的信息，以加深对生物物理机制在某些赤潮形成过程中的重要性的理解。培养未来的科学家：研究海洋中的生物物理相互作用需要生物学、流体力学和仪器方面的背景。该项目将在跨学科培训计划中支持一名这样的学生。

This project was submitted under the EU-US Cooperative Activity on the Ecology and Oceanography of Harmful Algae. The U.S. PIs will join colleagues from France, Ireland, Spain and UK to study the physics and biology of thin layers with concentrated Harmful Algal Bloom (HAB). Serious problems in Europe are caused by contamination of farmed shellfish with Diarrheic Shellfish Poisoning (DSP) toxins produced by the dinoflagellate genus Dinophysis. The existence of thin layers with high Dinophysis concentration has come to light recently, but the information is sporadic because the layers can be present at any depth, and due to sampling difficulties with standard instruments. In the case of Dinophysis, the concentration does not depend solely on nutrition, but also on interactions between physics, life cycle and behavior. This study will determine the hydrodynamic (e.g. local flow structure, turbulence, stratification, small gyres and pycnoclines), biological (e.g. growth, nutrition and mortality) and chemical environment leading to the build up, maintenance and population dynamics of Dinophysis in thin layers. The field tests will take place under a variety of hydrodynamic regimes in the Rias of Galicia (NWSpain), the estuarine plume zones of the Atlantic coast of France, and in the bays of southwestern Ireland. All are shellfish production areas with history of harvest closures due to contamination with DSP toxins. The Johns Hopkins group will focus on small-scale biophysical and particle-particle interactions. By deploying a submersible holocamera, augmented with a digital holographic cinematography, they will observe and measure processes and interactions occurring at the critical scales of 10 mm to 10 cm. Automated data analysis tools will enable the investigators to process a large database under various conditions that will be used for parameterizing the behavior of Dinophysis. The results will include: i. The spatial and size distributions of different classes of particles. Particles larger than 10 mm are detected, and shapes can be defined in particles larger than 30 mm. ii. The nearest neighbor distance (NNS) within the same species, and between species, including predators and prey; iii. The instantaneous 3-D velocity distributions within the sample volume, which is used for calculating the local velocity, strain rate, vorticity, dissipation rate and turbulence intensity; iv. The swimming behavior (speed, trajectory, direction) of Dinophysis in its local environment; v. Direct observations on behavior, feeding and grazing of Dinophysis; vi. Conditional statistics of concentration, NNS and behavior based on local physical and biological parameters;Intellectual Merit: Progress in understanding of population dynamics of different phytoplankton species, including Dinophysis, requires detailed knowledge of their in-situ concentrations, behavior, and biophysical interactions. This project will deploy a new but proven/developed technology in the ocean in order to obtain detailed and unique insight on the interaction of dinoflagellates with their local biophysical environments. The results will illuminate processes affecting the formation and maintenance of thin layers containing Dinophysis. Broader Impacts. Socio-Economic Issues: HAB adversely affect health, tourism, fisheries and food production in the coastal ocean, causing closure of fisheries, illness and even death. This project will obtain essential information to develop such understanding of the importance of bio-physical mechanisms in the formation of some HABs. Education of future Scientists: Studies of biophysical interactions in the ocean require background in biology, fluid mechanics, and instrumentation. This project will support one such student in an interdisciplinary training program.