Dissecting, and revealing the controls on, the group-specific CO2 fixation budget of the Atlantic Ocean

剖析并揭示对大西洋特定群体二氧化碳固定预算的控制

基本信息

批准号：
NE/G005125/1
负责人：
David Scanlan
金额：
$ 39.76万
依托单位：
University of Warwick
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2009
资助国家：
英国
起止时间：
2009 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FG005125%2F1
关键词：
Dissecting revealing controls group specific

项目摘要

The oceans play a major role in determining world climate. In part this is due to the production of oxygen and the consumption of carbon dioxide (CO2) by very small, single celled photosynthetic organisms, the picophytoplankton. Picophytoplankton biomass is dominated by three main groups: the prokaryotic genera Prochlorococcus and Synechococcus, and eukaryotes comprising cells <5 micrometres in size. However, little is known of what goes on inside the picophytoplankton 'black box' particularly with respect to the distribution of carbon biomass and group-specific primary production, information which is fundamental to understanding the roles of these groups in the global C cycle. Very recently our team has optimised utilisation of radiotracer incubation-flow cytometric sorting technology, to reveal group-specific CO2 fixation rates at several stations in the North Atlantic. As well as revealing variability in group-specific CO2 fixation rates between sites this data reiterates the importance of the eukaryotic fraction in primary production estimates (contribution 25-50% dependent on location) even though numerically they are vastly outnumbered by their prokaryotic counterparts. Here, we propose to extend this work so that for the first time we can reveal group-specific CO2 fixation rates at the basin scale, as well as in both surface waters and at the deep chlorophyll maximum (DCM). We will perform this work along an Atlantic Meridional Transect, which traverses the Atlantic Ocean between the UK and the Falkland Islands, and in consecutive years, so that i) a complete group-specific CO2 fixation budget of the Atlantic Ocean is attained and ii) inter-annual variability can be assessed. Moreover, we will examine the precise contribution of different taxonomic lineages to the picoplankton group rates using fluorescent in situ hybridisation of sorted populations and lineage-specific oligonucleotide probes for the prokaryotic genera (Synechococcus and Prochlorococcus) or class-specific probes for the photosynthetic picoeukaryote (PPE) fraction. Hence, this project will provide fundamental information of the major 'players' and routes of CO2 fixation in situ, a process that underpins marine C cycling. Furthermore, we will investigate environmental control of group-specific C fixation rates using on-board bottle experiments following either nutrient addition or shifts in irradiance. This will allow us to understand how environmental perturbation controls the CO2 fixation potential of specific groups. We will couple this latter work with a functional genomics (transcriptomics) approach specifically targeted at the PPE fraction to provide a complementary molecular assessment of the potential regulatory factors controlling this group. This is based on the idea that transcriptional profiling will 'let the organism inform us of the key environmental parameters that these organisms are responding to'. Taken together this work will make major inroads in our understanding of the routes and controls of marine CO2 fixation, information which is essential for a predictive understanding of marine C cycling.

海洋在决定世界气候方面发挥着重要作用。部分原因是非常小的单细胞光合生物（超微型浮游植物）产生氧气并消耗二氧化碳 (CO2)。微微浮游植物生物量主要由三个主要类群组成：原绿球藻属和聚球藻属的原核生物，以及包含尺寸<5微米的细胞的真核生物。然而，人们对微型浮游植物“黑匣子”内部发生的事情知之甚少，特别是在碳生物量的分布和特定群体的初级生产方面，这些信息对于理解这些群体在全球碳循环中的作用至关重要。最近，我们的团队优化了放射性示踪剂孵化流式细胞术分选技术的利用，以揭示北大西洋几个站的特定群体的二氧化碳固定率。除了揭示地点之间群体特异性二氧化碳固定率的变异性之外，该数据重申了真核生物部分在初级生产估计中的重要性（贡献 25-50% 取决于位置），尽管在数量上它们远远落后于原核生物。在这里，我们建议扩展这项工作，以便我们首次能够揭示流域尺度以及地表水和深层叶绿素最大值（DCM）下特定群体的二氧化碳固定率。我们将沿着大西洋经线横断面（横跨英国和福克兰群岛之间的大西洋）连续几年开展这项工作，以便 i) 获得完整的大西洋特定群体二氧化碳固定预算，并且 ii)可以评估年际变化。此外，我们将使用分选种群的荧光原位杂交和原核生物属（聚球藻属和原绿球藻属）的谱系特异性寡核苷酸探针或光合超微型核生物的类特异性探针（ PPE）分数。因此，该项目将提供主要“参与者”的基本信息以及二氧化碳原位固定路线，这是支撑海洋碳循环的过程。此外，我们将在添加营养物或改变辐照度后，使用机载瓶实验来研究特定群体 C 固定率的环境控制。这将使我们能够了解环境扰动如何控制特定群体的二氧化碳固定潜力。我们将把后者的工作与专门针对 PPE 部分的功能基因组学（转录组学）方法结合起来，为控制该组的潜在调控因素提供补充分子评估。这是基于这样的想法：转录分析将“让生物体告诉我们这些生物体正在响应的关键环境参数”。总而言之，这项工作将在我们对海洋二氧化碳固定的路线和控制的理解方面取得重大进展，这些信息对于预测了解海洋碳循环至关重要。