RAPID: Synechococcus diversity and Fe stress and the relationship to dissolved metals in the Eastern Tropical South Pacific

单细胞蓝藻聚球藻是海洋中分布最广、光合作用最丰富的生物之一，对海洋初级生产力有很大贡献。它也非常多样化，到目前为止已经发现了16个支系。然而，这种多样性尚未与特定的、明确定义的生态位相关联。为了确定聚球藻多样性的重要性，很重要的一点是确定这些生态位是什么，也就是说，在某个区域中存在的分支是否对该地区的生物地球化学循环有很大影响？同时，还必须定义分支的分布，以便能够更清楚地了解聚球藻在海洋中的作用，以及它未来可能会如何变化。在一个受资助的项目中，研究人员Jill A Sohm(J.A.S.)研究了铁(Fe)在控制海洋聚球菌OCE-0825922原位分布和活动中的作用。和Eric Webb一直在绘制西太平洋、北大西洋和南大西洋以及洛杉矶海岸聚球藻分支的分布图，以便更好地确定聚球藻许多分支的生态位。在这个项目中，Webb和Sohm将参加2010年2月在东热带南太平洋(ETSP)进行的一次研究巡航，ETSP是一个数据贫乏的地区，对其微蓝细菌的生态知之甚少。虽然已经表明，来自第四分支的聚球藻在拟议邮轮更南边的上升流区域占据主导地位，但更远的离岸种群的多样性却没有得到很好的界定。这次巡航将允许将目前聚球藻分支分布的数据库扩展到几乎没有数据的地区，并在现有项目的基础上增加试验田工作，测试铁、光、温度和营养对野外种群多样性的具体影响。这些数据与同时进行的实验室研究相结合，将深入了解海洋变化对聚球藻分布和活动的潜在影响。除了确定铁限制对海洋聚球藻的活动和野外多样性的作用和影响外，该项目还将开发现场培养测试的、基于定量聚合酶链式反应的铁胁迫诊断方法，供社区使用。此外，调查人员将试图从该地区分离和提供聚球菌菌株；因为这样的代表并不存在。维护和增加韦伯实验室的培养物收藏对海洋学社区来说是一项重要的服务，因为这些菌株被免费发送给任何请求它们的研究人员。在这次巡航中获得的元数据将通过将其存入国家数据库与海洋学界共享。最后，该项目将为一名博士后研究员J.A.S.和一名研究生提供宝贵的研究巡航经验和职业发展。

The unicellular cyanobacterium Synechococcus is one of the most widespread and abundant photosynthetic organisms in the ocean, contributing substantially to marine primary production. It is also extremely diverse, with 16 clades identified so far. This diversity, however, has yet to be correlated with specific, well-defined ecological niches. It is important to define what these ecological niches are in order to determine the significance of Synechococcus diversity, i.e., does the clade present in a certain regime have a large impact on biogeochemical cycling in that area? In parallel, the distribution of the clades must also be defined, to able to understand more clearly the role of Synechococcus in the ocean, and how it might change in the future. In a the funded project, "The role of iron (Fe) in controlling in situ distributions and activities of marine Synechococcus OCE-0825922" investigators Jill A Sohm (J.A.S.) and Eric Webb have been mapping the distribution of Synechococcus clades in the western Pacific, the North and South Atlantic, and off the coast of Los Angeles, in order to better define the ecological niches of the many clades of Synechococcus. In this project, Webb and Sohm will participate in a research cruise occurring in February 2010 in the Eastern Tropical South Pacific (ETSP), a data poor region with little known about the ecology of its picocyanobacteria. While it has been shown the Synechococcus from clade four dominate the upwelling region farther south of the proposed cruise, the diversity of the population farther offshore is much less well defined. This cruise would allow expansion of the current database of Synechococcus clade distribution to an area where there is little to no data, and add experimental field work to an existing project, testing the specific affects of Fe, light, temperature and nutrients on the diversity of field populations. These data combined with concurrent lab research will provide insight into the potential of oceanic change to affect the distribution and the activity of Synechococcus.In addition to defining the role and impact of Fe limitation on marine Synechococcus activity and diversity in the field, this project will develop field incubation-tested, quantitative PCR-based Fe stress diagnostics that will be available to the community. Furthermore, the investigators will attempt to isolate and make available Synechococcus strains from the region; as such representatives are not in existence. The upkeep and addition to the culture collection in the Webb lab is an important service for the oceanographic community, as these strains are sent to any researcher that requests them without charge. Metadata obtained on this cruise will be shared with the oceanographic community by depositing them in a national database. Lastly this project will provide valuable research cruise experience and career development for one post-doctoral fellow, J.A.S., and one graduate student.