Top-Down Regulation of Picophytoplankton in the Sargasso Sea: Application of a Reciprocal Transplant / Dilution Approach

马尾藻海中微型浮游植物的自上而下调节：相互移植/稀释方法的应用

• 批准号: 0751672
• 负责人: Brian Binder
• 金额: $ 38.29万
• 依托单位: University of Georgia Research Foundation Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-03-01 至 2013-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0751672&HistoricalAwards=false
• 关键词: Top; Down; Regulation; Picophytoplankton; Sargasso

The intellectual merit of the research is to extend our understanding of the biology and ecology of marine picophytoplankton, a group of microbes that are responsible for a large proportion of the total photosynthetic carbon fixation that occurs in the world's oceans. The importance of picophytoplankton as the dominant primary producers in open-ocean ecosystems is well-established. However, the factors that regulate the distribution and abundance of these populations remain poorly understood. The investigators will explore the dynamics of top-down (grazer-mediated) regulation of picophytoplankton populations in a specific context: the maintenance of summertime subsurface maxima in the pico-cyanobacterium Prochlorococcus (but not Synechococcus) in the Sargasso Sea. This phenomenon represents a relatively simple and predictable model system within which to test hypotheses about the regulation of oceanic picophytoplankton in general. Recent results suggest that despite their abundance, Prochlorococcus in the subsurface maxi-mum are growing (and being grazed) rather slowly, as compared to the smaller population at the surface. In order to understand the factors responsible for this apparent paradox, this project will use a combination of field and laboratory studies to characterize and compare the interactions between Prochorococcus and its protozoan grazers at these two contrasting depths, and in relation to Synechococcus, which forms no such sub-surface maximum. The broader impacts include training for graduate and undergraduate students. In addition, given the significance of picophytoplankton as primary producers at the base of oceanic microbial food webs, the results of this project should inform efforts to describe and model the broader oceanic ecosystem, and ultimately to understand its role in the global carbon cycle.

这项研究的智力价值是扩大我们对海洋微型浮游植物的生物学和生态学的理解，微型浮游植物是一组微生物，负责世界海洋中发生的总光合固碳的很大一部分。 微型浮游植物作为公海生态系统中主要初级生产者的重要性已得到公认。 然而，调节这些种群的分布和丰度的因素仍然知之甚少。 研究人员将探讨自上而下（食草介导）的调节picophytoplankton种群在特定情况下的动态：维护夏季地下最大的pico-cyanobacterium Prochlorococcus（但不是Synechococcus）在马尾藻海。 这种现象代表了一个相对简单和可预测的模型系统，在其中测试的海洋picophytoplankton一般的调节假说。 最近的研究结果表明，尽管它们的丰度，原绿球藻在地下最大的增长（和被放牧）相当缓慢，相比，在表面的较小的人口。 为了了解造成这一明显矛盾的因素，该项目将使用实地和实验室研究相结合的方法来表征和比较原球藻和原生动物食草动物在这两个对比深度之间的相互作用，其不形成这种次表面最大值。 更广泛的影响包括对研究生和本科生的培训。 此外，鉴于微型浮游植物作为海洋微生物食物网基础的初级生产者的重要性，该项目的结果应有助于描述和模拟更广泛的海洋生态系统，并最终了解其在全球碳循环中的作用。