Hydrodynamic forcing of Alexandrium population biology

有毒甲藻Alexandiumfundyense的水华是每年春季和夏季在缅因州海湾经常发生的现象。A. fundyense在滤食性贝类如贻贝和蛤的组织中积累。人类摄入这些受污染的贝类可能导致麻痹性贝类中毒（PSP），这是一种潜在的致命疾病。了解决定A.因此，Fundyense具有相当大的经济和公共卫生利益。现有的数据和模型表明，A。fundyense种群和缅因州湾沿岸流系统。事实上，人口的物理-生物耦合模型 动力学和水动力输运能够模拟所观察到的A. Fundyense分布然而，这样的模型是敏感的输入参数的选择（例如，生长速率，游泳速度，发芽率等）。奇怪的是，模型与观测值相匹配的能力发生在这个参数空间的范围内，这个参数空间相对于实验室和现场测量所定义的合理值的包络线来说是相对狭窄的。对这种明显的不一致性的一个可能的解释是自然种群中的遗传异质性。我们假设A. Fundyense由遗传上不同的亚群的镶嵌体组成，每个亚群对环境条件具有不同的生理和/或行为反应。该项目的目标是了解这些种群的水动力和生物控制，它们的毒素生产，以及这些因素如何最终决定贝类毒性的波动。

Blooms of the toxic dinoflagellate Alexandrium fundyense are annually recurrent phenomena in the Gulf of Maine during the spring and summer months. Toxins produced by A. fundyense accumulate in the tissues of filter-feeding shellfish such as mussels and clams. Human ingestion of these contaminated shellfish can lead to Paralytic Shellfsh Poisoning (PSP), a potentially fatal illness. Understanding the factors that determine the distribution and abundance of A. fundyense is therefore of considerable economic and public health interest. Existing data and models demonstrate strong interconnections between A. fundyense populations and the Gulf of Maine coastal current system. Indeed, coupled physical-biological models of population dynamics and hydrodynamic transport are able to simulate some of the general features of the observed A. fundyense distribution. However, such models are sensitive to the choices of the input parameters (e.g. growth rate, swimming speed, germination rate, etc). Curiously, the ability of the models to match the observations occurs in a range of this parameter space that is relatively narrow with respect to the envelope of reasonable values defined by laboratory and field measurements. One possible explanation for this apparent inconsistency is genetic heterogeneity in the natural populations. We hypothesize that the aggregate distribution of A. fundyense is composed of a mosaic of genetically distinct subpopulations, each with different physiological and/or behavioral responses to environmental conditions. The goal of this project is to understand the hydrodynamic and biological controls on these populations, their toxin production, and how these factors ultimately determine fluctuations in shellfish toxicity.