A new perspective on ocean photosynthesis (N-POP)

海洋光合作用的新视角（N-POP）

• 批准号: NE/W000903/1
• 负责人: Thomas Bibby
• 金额: $ 82.76万
• 依托单位: University of Southampton
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FW000903%2F1
• 关键词: new; perspective; ocean; photosynthesis; POP

Sunlight penetrating into the ocean is the ultimate source of energy in oceanic ecosystems. This energy sustains fisheries and catalyses biogeochemical cycles that influence the carbon cycle and ultimately climate. Single-celled photosynthetic organisms termed phytoplankton are the gatekeepers of this energy flux, achieved via the absorption of light by photosynthetic pigments such as chlorophyll. However, the range of processes in the cell that determine how this light energy is subsequently used to support growth and survival of these crucial organisms are not well characterised. This 'knowledge gap' is a result of the current paradigm that mainly considers photosynthesis in terms of the amount of 'carbon fixed' rather than 'energy captured'. Here we propose that natural phytoplankton taxa are more adaptable in their energetic metabolism than currently assumed, using different 'molecular strategies' to specifically power a range of critical cellular processes beyond carbon fixation. These different strategies potentially represent more than half of photosynthetic energy flux in many circumstances. The corresponding diversity of metabolic strategies is thus likely to represent a fundamental process through which these crucial organisms adapt to thrive across different ocean ecosystems.We will obtain an improved understanding of how phytoplankton use light energy in ocean systems, which is critical to our ability to understand how oceanic ecosystems operate and thus predict how the ecosystem services they provide (including sustaining fisheries, sequestering atmospheric CO2 and producing other climate reactive gases) may change as the global system evolves. For example, we currently use satellites to measure the colour of the ocean and hence estimate phytoplankton abundance and infer rates of primary production without a full mechanistic understanding of how these phytoplankton use the available light energy. Such understanding of the coupling of light energy capture to cellular survival, growth rate and carbon fixation is crucial for facilitating better estimates of primary production and ultimately understanding the key role of the oceanic biota in the global carbon cycle. To achieve this, we propose an observational and experimental program that will define how diverse phytoplankton communities use light energy over natural gradients in nutrient and light availability. We will undertake a research cruise encompassing the South Atlantic, as well as the iron-limited regions of the Southern Ocean, to sample natural phytoplankton communities at sea. These will be analysed to determine their rates of photosynthesis and, through molecular functional and community structure analysis, to define the processes involved in harvesting and using photosynthetic energy. The information from the natural community experiments will be extrapolated to a larger scale via network analysis and mapping approaches to generate a global understanding of how cells use light energy.Our deliverables will be an observationally and experimentally derived integrated view of the environmental and physiological controls on how phytoplankton in ocean systems actually use light energy to power all cellular processes (beyond only considering carbon fixation) (OB1 and OB2), and a global-scale synoptic synthesis of where and when different photosynthetic strategies are used by phytoplankton (OB3). We expect this to move the paradigm away from the 'carbon-centric view' to more fully consider the potentially >50% of phytoplankton light energy usage that powers the metabolisms of the organisms underpinning the productivity of ocean ecosystems.

穿透海洋的阳光是海洋生态系统能量的最终来源。这种能量维持着渔业，并催化影响碳循环并最终影响气候的生物地球化学循环。被称为浮游植物的单细胞光合生物是这种能量流的守门人，通过叶绿素等光合色素吸收光来实现。然而，细胞中决定这些光能随后如何用于支持这些关键生物体生长和生存的一系列过程尚未得到很好的表征。这种“知识差距”是当前范式的结果，该范式主要从“固定碳”的数量而不是“捕获的能量”的角度来考虑光合作用。在这里，我们提出，天然浮游植物分类群在能量代谢方面的适应性比目前认为的要强，它们使用不同的“分子策略”来特定地为碳固定以外的一系列关键细胞过程提供动力。在许多情况下，这些不同的策略可能代表了超过一半的光合能量通量。因此，代谢策略的相应多样性很可能代表了这些关键生物适应在不同海洋生态系统中茁壮成长的基本过程。我们将更好地了解浮游植物如何在海洋系统中利用光能，这对我们了解海洋生态系统如何运作，从而预测它们提供的生态系统服务（包括维持渔业、隔离大气二氧化碳和产生其他气候反应性气体）如何随着全球系统的演变而变化的能力至关重要。例如，我们目前使用卫星来测量海洋的颜色，从而估计浮游植物的丰度，并推断初级生产的速度，而没有完全了解这些浮游植物如何利用可用光能。这种对光能捕获与细胞存活、生长速率和碳固定耦合的理解对于促进更好地估计初级生产和最终理解海洋生物群在全球碳循环中的关键作用至关重要。为了实现这一目标，我们提出了一个观察和实验计划，该计划将定义不同的浮游植物群落如何在营养和光可用性的自然梯度上利用光能。我们将进行一次环绕南大西洋以及南大洋铁含量有限地区的考察巡航，对海上的天然浮游植物群落进行取样。这些将被分析，以确定其光合作用的速率，并通过分子功能和群落结构分析，以确定在收获和利用光合能量所涉及的过程。来自自然群落实验的信息将通过网络分析和绘图方法外推到更大的范围，以产生对细胞如何使用光能的全球理解。我们的成果将是通过观测和实验得出的环境和生理控制的综合观点，即海洋系统中的浮游植物如何实际利用光能为所有细胞过程提供动力（不仅仅考虑碳固定）（OB1和OB2），以及浮游植物在何时何地使用不同光合作用策略的全球尺度综合（OB3）。我们希望这能将范式从“以碳为中心的观点”转移到更充分地考虑浮游植物潜在的50 - 50%的光能使用，这些光能为支撑海洋生态系统生产力的生物代谢提供动力。