Hydrodynamic forcing of Alexandrium population biology

每年春季和夏季，缅因湾都会出现有毒的甲藻亚历山大藻大量繁殖的现象。 A.fundyense 产生的毒素积聚在滤食性贝类（例如贻贝和蛤）的组织中。人类摄入这些受污染的贝类可能会导致麻痹性贝类中毒（PSP），这是一种潜在的致命疾病。因此，了解决定 A.fundyense 分布和丰度的因素具有相当大的经济和公共卫生意义。现有数据和模型表明 A.fundyense 种群与缅因湾沿岸海流系统之间存在紧密的联系。事实上，人口的耦合物理生物模型 动力学和流体动力传输能够模拟观察到的 A.fundyense 分布的一些一般特征。然而，此类模型对输入参数（例如生长速率、游泳速度、发芽率等）的选择很敏感。奇怪的是，模型与观测结果相匹配的能力发生在该参数空间的范围内，该范围相对于实验室和现场测量定义的合理值的范围相对较窄。这种明显不一致的一种可能解释是自然群体中的遗传异质性。我们假设 A.fundyense 的总体分布由遗传上不同的亚群组成，每个亚群对环境条件有不同的生理和/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、它们的毒素产生，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.