Taxon-specific contributions to export production - Development of biomarker approaches

特定分类单元对出口生产的贡献 - 生物标记方法的开发

• 批准号: 0118038
• 负责人: Ralf Goericke
• 金额: $ 35.56万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-10-01 至 2005-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0118038&HistoricalAwards=false
• 关键词: Taxon; specific; contributions; export; production

Photoautotrophic picoplankton contribute significantly to phytoplankton biomass and primary production in the ocean. The smallest known photoautotroph is Prochlorococcus sp. It is unusual because its primary photosynthetic pigment is divinyl-chlorophyll a (Chl a2), a unique biomarker for this organism. The traditional view of the marine food web suggests that carbon assimilated by Prochlorococcus, and other picoautotrophs, is primarily recycled within the microbial web. High concentrations of Chl a2-degradation products found in surficial sediments and sediment trap material from the Eastern Tropical North Pacific suggest that Prochlorococcus may nonetheless contribute significantly to export production in that environment. This inference depends on the assumptions that 1) water column concentrations of Chl a2 and Chl a1 are equally good proxies for the biomass of Prochlorococcus and other phytoplankters, respectively, 2) the chlorin-conversion efficiencies of Chl a1 and Chl a2, when ingested by herbivores, are similar and 3) the diagenesis of chlorins in sediments does not alter the ratio of Chl a1 and Chl a2-derived chlorins. The first objective of this proposal is to test these assumptions to place inferences based Chl a1/ a2-ratios on a firm basis. Knowing the relative contributions of Prochlorococcus to export production would allow one to calculate the contributions of picoplankton in general. These fluxes are likely mediated by pelagic tunicates, assuming that chlorins entering the microbial loop are quickly degraded and that pelagic tunicates, or at least some of these, are the only macrozooplankters capable of grazing on Prochlorococcus. Testing these two assumptions in the field is the second objective of this proposal. The proposed work constitutes a biomarker approach that will enable us to measure the contribution of Prochlorococcus and picoplankters to export production. These tools will help us understand the sources and controls of export production in the open ocean. This added understanding will contribute to our ability to predict the effects of environmental change on open ocean ecosystem.

光合自养微型浮游生物对海洋浮游植物生物量和初级生产力有重要贡献。已知最小的光合自养生物是原绿球藻，它是不寻常的，因为它的主要光合色素是二乙烯基叶绿素a（Chl a2），这是一个独特的生物标志物。海洋食物网的传统观点认为，原绿球藻和其他微微自养生物吸收的碳主要在微生物网内循环。高浓度的叶绿素a 2-降解产物中发现的表层沉积物和沉积物陷阱材料从东热带北太平洋表明，原绿球藻可能仍然有助于显着的出口生产环境。这一推论依赖于以下假设：1）水体中Chl a2和Chl a1的浓度分别是原绿球藻和其他植食性藻类生物量的良好替代物; 2）Chl a1和Chl a2在被食草动物摄取时的叶绿素转化效率相似; 3）沉积物中二氢酚的成岩作用不会改变Chl a1和Chl a2衍生的二氢酚的比例。本提案的第一个目标是测试这些假设，以确定基于叶绿素a1/ a2比值的推断。了解原绿球藻对输出产量的相对贡献将使人们能够计算出微型浮游生物的贡献。这些通量很可能介导的浮游被囊类，假设进入微生物循环的二氢卟酚迅速降解，浮游被囊类，或至少其中的一些，是唯一的macrozooterters能够放牧原绿球藻。本建议的第二个目标是在实地检验这两个假设。拟议的工作构成了一个生物标志物的方法，将使我们能够衡量原绿球藻和picobacterists的出口生产的贡献。这些工具将帮助我们了解公海出口生产的来源和控制。这种额外的理解将有助于我们预测环境变化对开放海洋生态系统的影响。