Project 1: Harmful algal bloom dynamics: assessing physiological and behavioral plasticity in natural populations

丰迪亚历山大藻和拟菱形藻。目前，公共卫生威胁不断扩大， 相关中毒综合征，麻痹性贝类中毒和失忆性贝类中毒。一个主要 令人担忧的是，这些有害藻华（HAB）及其对人类健康的影响将在多大程度上受到 因气候变化而改变缅因州海湾是探索这一问题的理想场所，因为它的长期 A的历史fundyense调查研究开花生理学，毒性和开花动力学，导致 建立一个强大的人口动态模型。然而，气候变化下的现实预测 条件仍然具有挑战性的两个A. fundyense和Pseudo-nitzschia，一种新兴的研究较少的 威胁目前的模型A. fundyense依赖于基于文化的行为特征， 自然环境，正如我们在之前的WHCOHH期间进行的新的原位观察所证明的那样 程序.生命周期过程，生长，放牧和死亡率，以及游泳模式都被 发现在原地有显着不同，使得基于文化的数据不足以进行模型评估。一 第二个挑战来自这些生物群的适应潜力，它们的生理变化很大 在他们的范围内。这个项目的科学前提是，我们评估和预测短期和长期的能力- 这些有害生物的长期反应及其对人类健康对气候变化的影响，需要确定以下特征： 在自然种群中的临界速率和行为模式，只要有可能， 意见。根据对冷量调节冬小麦休眠期的新发现， Fundyense包囊在Nauset沼泽河口，目标1将评估这种反应的可塑性，在多个 栖息地和种群，并探讨是否A.芬迪恩斯群岛 适应范围广。目标2将使用原位技术来确定温度 和A. fundyense分裂，放牧，积累和毒性发作在一系列的栖息地。先前 WHCOHH的工作发现了A.瑙塞特地区的芬迪人 马什如果其他栖息地的生长率也同样升高，则将这些速率纳入生长度- 日和更复杂的，机械模型承诺改善预测水华的时间和毒性， 气候变化评估。目标3将确定细胞浓度阈值、寄生虫感染和 迁移的变化有助于A. Fundyense Bloom终止。目标4将大大扩展知识基础， 通过结合先前和新的现场和实验室观测研究拟菱形藻水华动力学。 拟菱形藻物种组成是毒性的一级预测因子， 毒性预测需要物种生理和生活史动力学之间的差异。在 总之，该项目将提供发展和完善水华动力学所需的现场评估 气候预测和人类接触有害藻华毒素估计的基础模型（项目2和3）。

Alexandrium fundyense and Pseudo-nitzschia spp. present expanding public health threats through their associated poisoning syndromes, paralytic shellfish poisoning and amnesic shellfish poisoning. A major concern is the extent to which these harmful algal blooms (HABs) and their human health impacts will be altered by a changing climate. The Gulf of Maine is an ideal setting to explore this problem due to its long history of A. fundyense investigations examining bloom physiology, toxicity, and bloom dynamics, leading to construction of a robust population dynamics model. Nevertheless realistic forecasts under changing climate conditions remain challenging for both A. fundyense and Pseudo-nitzschia, an emerging and less studied threat. Current models for A. fundyense rely on culture-based characterizations of behavior that are not valid in the natural environment, as demonstrated by novel in situ observations made during our prior WHCOHH program. Life cycle processes, growth, grazing and mortality rates, and swimming patterns have all been found to be significantly different in situ, making culture-based data inadequate for model assessments. A second challenge stems from the adaptive potential of these taxa, whose physiologies vary substantially across their ranges. This project's scientific premise is that our ability to assess and predict short- and long- term responses of these HABs and their human health impacts to climate change requires characterization of critical rates and behavioral patterns in natural populations, generated, whenever possible, through in situ observations. Based on the new finding of a chilling requirement regulating the dormancy period of A. fundyense cysts in the Nauset Marsh estuary, Aim 1 will assess plasticity of this response across multiple habitats and populations and explore whether the temperature conditioning requirements of A. fundyense are adaptive across its range. Aim 2 will use in situ technologies to determine relationships between temperature and A. fundyense division, grazing, accumulation, and toxicity onset across a range of habitats. Previous WHCOHH work discovered unexpectedly high accumulation and division rates for A. fundyense in Nauset Marsh. If growth is similarly elevated across other habitats, incorporation of these rates into growing degree- day and more complex, mechanistic models promise improved predictions of bloom timing and toxicity and climate change assessments. Aim 3 will establish how cell concentration thresholds, parasite infections, and migration shifts contribute to A. fundyense bloom termination. Aim 4 will greatly expand the knowledge base for Pseudo-nitzschia bloom dynamics by combining previous and new in situ and lab-based observations. Pseudo-nitzschia species composition is a first order predictor of toxicity, so knowledge of species diversity and differences between species' physiology and life cycle dynamics is needed for toxicity predictions. In summary, the project will provide the in situ assessments needed to develop and refine the bloom dynamics models that underlie climate projections and estimates of human exposure to HAB toxins (Projects 2 and 3).