Collaborative Research: Seasonal bloom dynamics: Synechococcus-grazer interactions as a model system

聚球藻属中的蓝藻是微小的，但在温带海洋中无处不在的浮游植物，它们贡献了海洋食物网底部产生的大量生物量。聚球藻的季节性水华是大西洋和太平洋沿岸水的一个非常一致的特征。然而，新的分子技术揭示了这些水华的一致性背后是丰富的遗传变异，表现出快速的动态更替。这导致了一种假设，即聚球藻中的遗传多样性对于维持季节性水华和预测海洋生态系统对长期环境变化的反应具有重要的生态学意义。该项目将结合生态学和基因组学方法，了解遗传多样性如何与推动聚球藻水华季节性循环的物理和食物网过程相互作用。在缅因湾的布斯湾和南加州的斯克里普斯码头，将每周对聚球藻和共生微生物的遗传多样性进行量化。我们将利用流式细胞术细胞分选与分子方法相结合的三个层次的方法来研究水华群落的多样性，包括：整个未分选群落的DNA和RNA分析，流动分选群落的DNA分析，以及聚球藻及其原生食草动物的单细胞基因组学。将通过实验来研究导致聚球藻水华结束的生态过程，该实验旨在衡量原生动物食草动物死亡与不同聚球藻生态型病毒死亡的相对重要性。这些结果将深入了解水华动态以及遗传多样性如何与生态系统过程相互作用。该项目将开发一般有用的方法和资源，用于量化浮游植物季节性水华的变异性，这可能是生态系统对较长期气候变化反应的早期指标。将设计定量聚合酶链式反应方法，以快速量化聚球藻和海洋水域中聚球藻的多样性。将产生大量原生生物和聚球藻的单一扩增基因组，并进行冷冻保存，以便将来进行研究。该项目还将支持一名研究生和几名本科生的研究培训，他们将密切参与个别项目。结果将转化为在毕格罗实验室举办的正式课程，并通过在每年夏天在布斯贝港成功举办的每周一次的咖啡馆科学系列活动上向公众介绍。

Cyanobacteria in the genus Synechococcus are minute, but ubiquitous phytoplankton of temperate oceans that contribute a large amount of the biomass produced at the base of marine food webs. Seasonal blooms of Synechococcus are a remarkably consistent feature of coastal water of both the Atlantic and Pacific oceans. However, new molecular techniques have revealed that underlying the consistency of these blooms is a wealth of genetic variation that exhibits rapid dynamical turnover. This has led to a hypothesis that genetic diversity within Synechococcus is ecologically important to sustaining seasonal blooms, and to predicting marine ecosystem response to longer term environmental change. This project will combine ecological and genomic approaches to understand how genetic diversity interacts with the physical and food web processes that drive seasonal cycles of Synechococcus blooms. The genetic diversity of Synechococcus and co-occurring microbes will be quantified on a weekly basis during bloom periods in Booth Bay, Gulf of Maine and Scripps Pier, Southern California. Flow cytometric cell sorting in combination with molecular approaches will be utilized to investigate the diversity of bloom assemblages using a three-tiered approach including: DNA and RNA analysis of the whole unsorted community, DNA analysis of flow-sorted communities, and single cell genomics of Synechococcus and their protist grazers. Ecological processes that cause Synechococcus blooms to end will be investigated through experiments designed to measure the relative importance of mortality from protist grazers versus from viruses on various Synechococcus ecotypes. These results will yield insights into bloom dynamics and how genetic diversity interacts with ecosystem processes.This project will develop methods and resources that will be generally useful for quantifying variability of the seasonal bloom of phytoplankton, which is likely to be an early indicator of ecosystem responses to longer term climate change. Quantitative PCR methods will be designed for rapid quantification of diversity in Synechococcus and in Synechococcus grazers in marine waters. Numerous protist and Synechococcus single amplified genomes will be produced and cryo-preserved to enable future studies. This project will also support the research training of a graduate student and several undergraduate students, who will be intimately involved with individual projects. Results will be translated to formal courses held at Bigelow Laboratory and to the public through presentations at a successful weekly Café Scientifique series held in Boothbay Harbor each summer.