Physiological Ecology of Marine Cyanobacterial Communities

9633111 Palenik该项目将采用多调查员综合办法，以确定海洋环境中蓝藻生物多样性的范围和原因。该项目的假设是，海洋的层化虽然往往是短暂的，但已导致发展出数量有限的在生理和遗传上不同和可识别的蓝藻群体(“物种”)，特别适应高光、低营养混合层，以及其他适应高营养、低光混合层的蓝藻。即使是这种简单的情景，也比目前的海洋学范式复杂得多。目前对自然蓝藻多样性的空间或时间变化知之甚少，我们只能猜测可能推动这种变化的因素。这种多样性在决定海洋速率过程中可能具有的重要性尚不清楚，例如原位生长或固碳速率，在我们了解蓝藻多样性的范围和模式之前，它的作用无法真正得到解决。这个项目是能够分析个体生理或遗传类型的生长速度和代谢活动的第一步。由于类似的遗传和生理过程可能也发生在其他浮游植物群体中，这些问题对生物海洋学具有普遍意义。这个项目还将开始研究环境中微生物“物种”的数量，但为什么会有这样的数量？海洋环境的微生物区系正变得非常多样化，通过详细审查相关微生物组的多样性与物理化学参数的关系，最好地了解这种多样性背后的过程。海洋环境可能是开始理解这些问题的最佳起点，因为在理解组织周围的物理化学梯度方面也有相当多的经验。来自菌株和大量群落样本的RNA聚合酶基因序列、流式细胞仪分析、色素分析、运动性聚球菌和其他菌株的抗体分析、菌株分离技术、关于氮和光利用的生理研究以及物理化学数据将是我们将带来解决这些问题的第一套工具，其他工具正在开发中。为了确保我们结论的重现性，将在同一季节连续两年在南加州海湾的贫营养边界上连续两年在几个深度进行采样。第三次巡航将集中于同一地点在不同季节的特征，以便开始探索多样性的时间变化。这种集中的采样工作将确保采用一种易于处理的方法来了解蓝藻多样性对海洋生态系统的重要性。***

9633111 PALENIK This project will use an integrated multi-investigator approach to determine the extent and causes of cyanobacterial biodiversity in the marine environment. The project hypothesis is that stratification in the oceans, although often transient, has led to the development of a limited number of physiologically and genetically distinct and recognizable groups ("species") of cyanobacteria specifically adapted to the high light, low nutrient mixed layer and others adapted to the higher nutrient, low light life below it. Even this simple scenario is much more complex than the current oceanographic paradigm. There is currently little knowledge of the spatial or temporal variations in natural cyanobacterial diversity, and we can only guess at the factors that may be driving it. The importance this diversity may have in determining oceanographic rate processes, such as in situ growth or carbon fixation rates, is unknown, and its role cannot really be addressed until we understand the extent and patterns of cyanobacterial diversity. This project is the first step in being able to assay the growth rates and metabolic activities of individual physiological or genetic types. Since similar genetic and physiological processes probably also occur in other groups of phytoplankton, these questions are of general significance to biological oceanography. This project will also begin to look at not just the number of microbial "species" in an environment, but why that number? The microbiota of the marine environment are coming to be seen as remarkably diverse, and an understanding of the processes underlying this diversity will best be gained by examining the diversification of a related group of microorganisms in detail in relationship to physiochemical parameters. The marine environment is probably the best place to begin to understand these questions because there is also considerable experience in understanding the physiochemical gradients surrounding the o rganisms. RNA polymerase gene sequences from strains and bulk community samples, flow cytometric analyses, pigment analyses, antibody assays for motile Synechococcus and other strains, strain isolation techniques, physiological studies on nitrogen and light utilization, and physiochemical data will be the initial set of tools we will bring to these problems, with others under development. Three sites in the oligotrophic boundary of the Southern California Bight will be sampled at several depths for two consecutive years at the same season to ensure the reproducibility of our conclusions. A third cruise will focus on characterizing the same sites at a different season in order to begin to explore temporal variations in diversity. This focused sampling effort will ensure a tractable approach to understanding the importance of cyanobacterial diversity to marine ecosystems. ***