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

亚历山大藻(Alexandrium Fundyense)和拟菱形藻(Passo-Nitzschia spp.)通过以下方式呈现不断扩大的公共卫生威胁 相关中毒综合征、麻痹性贝类中毒和健忘性贝类中毒。一位少校 令人担忧的是这些有害的藻华(HAB)及其对人类健康的影响将在多大程度上 因气候变化而改变的。缅因湾是探索这个问题的理想地点，因为它有很长的时间 研究开花生理、毒性和开花动态的真菌研究的历史，导致 构建稳健的种群动力学模型。尽管如此，气候变化下的现实预测 对于一种新兴的、研究较少的拟菱形藻来说，条件仍然具有挑战性。 威胁。目前的A.fundyense模型依赖于基于文化的行为特征，而这些特征在 自然环境，正如在我们之前的WHCOHH期间所做的新颖的现场观察所证明的那样 程序。生命周期过程、生长、放牧和死亡率以及游泳模式都 发现在现场有显著不同，使得基于文化的数据不足以进行模型评估。一个 第二个挑战来自这些类群的适应潜力，它们的生理学差异很大。 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- 这些赤潮对气候变化的长期反应及其对人类健康的影响需要表征 自然种群中的临界率和行为模式，只要可能，通过现场生成 观察。基于调节黄曲霉休眠期的冷藏需求的新发现。 Nauset Marsh河口的Fundyense包囊，Aim 1将评估这种反应的可塑性 栖息地和种群，并探索真菌对温度的调节要求是否 在其范围内具有适应性。AIM 2将使用现场技术来确定温度之间的关系 和真菌的分裂，放牧，积累和毒性开始在一系列的栖息地。上一首 WHCOHH工作在Nauset发现了出人意料的高蓄积率和分裂率 马什。如果其他栖息地的生长速度同样较高，则将这些速度纳入增长程度- 和更复杂的机械模型保证了对开花时间和毒性的更好的预测 气候变化评估。目标3将确定细胞浓度阈值、寄生虫感染和 迁徙转移是风信子水华终止的重要原因。目标4将极大地扩展知识库 通过结合以前和新的现场观测和基于实验室的观测来研究假菱形藻水华动力学。 伪菱形藻的物种组成是毒性的一级预测因子，因此对物种多样性的了解 而物种的生理和生命周期动态之间的差异是毒性预测所必需的。在……里面 总之，该项目将提供开发和完善水华动态所需的现场评估 作为气候预测和人类暴露于HAB毒素的估计的模型(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).