Elucidating the consequences of picocyanobacterial lipid remodelling for global marine primary production estimates

阐明微微蓝藻脂质重塑对全球海洋初级生产力估算的影响

• 批准号: NE/V000462/1
• 负责人: Jeremy Blackford
• 金额: $ 22.24万
• 依托单位: Plymouth Marine Laboratory
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FV000462%2F1
• 关键词: Elucidating; consequences; picocyanobacterial; lipid; remodelling

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 organisms, which are referred to as the photosynthetic picoplankton. Marine cyanobacteria of the closely-related genera Prochlorococcus and Synechococcus are the prokaryotic components of the photosynthetic picoplankton and are the two most abundant phototrophs on Earth! By fixing CO2 from the atmosphere into biomass these organisms act as a sink for this key greenhouse gas. This process of carbon (C) sequestration, known as the biological C pump, is the greatest form of natural capital we possess in the fight against climate change. Whilst these cyanobacteria are continually growing and dividing, one of the most important factors controlling the rate at which they grow, and hence the amount of carbon dioxide that is fixed through photosynthesis, is the availability of nutrients. Oceanic regions vary considerably in their supply of these essential nutrients e.g. phosphorus (P), nitrogen (N) and iron. In oceanic regions where the levels of P are low e.g. the North Atlantic Ocean and Mediterranean Sea picocyanobacteria modify their cellular constituents to conserve P. They do this by remodelling their lipid composition. Membrane lipids form the structural basis of all cells, acting as a barrier between the cell and the external environment. Phospholipids are a major component of cyanobacterial cell membranes but under conditions of P depletion these P-containing lipids are replaced with non-P containing sulfolipids. The physiological and ecological consequences of this natural remodelling process are unknown. In other words we do not know how this remodelling affects rates of CO2 fixation or how this affects the ability of these organisms to transport (acquire) other nutrients and in turn affects the elemental composition of these organisms and the rate at which they release organic C. This is important because not only are marine cyanobacteria critical contributors to global CO2 fixation but their abundance is expected to increase in future years due to expansion of ocean gyres as a result of global warming. Thus, understanding whether their primary production will decline, increase or remain unchanged in the face of climate warming and the mechanisms causing this are ultimately critical to forecasting future changes in the functioning of marine ecosystems.Hence, in this proposal we will determine how lipid remodelling during P deplete growth under both current and elevated CO2 levels, affects the ability of marine cyanobacteria to fix CO2, acquire key macro- and micro-nutrients thereby modifying their elemental composition. This has consequences not only for accurate primary production estimates but also for the nutritional quality of these cells as prey for grazers (and hence for energy transfer to higher trophic levels) and conversely the elemental composition of cells removed from the water column when cells sink - and thus C, N and P export. We will also determine whether limitation for N also triggers a lipid remodelling response, and if so, its consequences. All of the data obtained will be used to refine current ecosystem model formulations describing the effect of nutrient limitation on primary production. The new formulation that takes into account the effect of lipid remodelling on primary production, will be implemented into the European Regional Seas Ecosystem Model (ERSEM) providing a substantially improved simulation of oceanic primary production.Overall, the proposal will therefore provide direct estimates, and a mechanistic basis, for understanding the role of lipid remodelling in controlling marine primary production. Data and concepts will subsequently be used in ERSEM to refine control points for marine photosynthesis and subsequent carbon cycling and ultimately enhance their predictive capability.

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生物（被称为光合超微型浮游生物）产生氧气并消耗二氧化碳 (CO2)。密切相关的原绿球藻属和聚球藻属的海洋蓝藻是光合超微型浮游生物的原核成分，也是地球上两种最丰富的光养生物！通过将大气中的二氧化碳固定到生物质中，这些生物体充当了这种关键温室气体的汇。这种碳（C）封存过程被称为生物碳泵，是我们应对气候变化所拥有的最重要的自然资本形式。虽然这些蓝细菌不断生长和分裂，但控制它们生长速度以及通过光合作用固定的二氧化碳量的最重要因素之一是营养物质的可用性。海洋地区这些必需营养素的供应差异很大，例如海洋。磷（P）、氮（N）和铁。在磷含量较低的海洋地区，例如北大西洋和地中海的微微蓝藻改变其细胞成分以保存磷。它们通过重塑其脂质成分来做到这一点。膜脂质构成所有细胞的结构基础，充当细胞与外部环境之间的屏障。磷脂是蓝藻细胞膜的主要成分，但在磷耗尽的条件下，这些含磷脂质被不含磷的硫脂取代。这种自然重塑过程的生理和生态后果尚不清楚。换句话说，我们不知道这种重塑如何影响二氧化碳固定速率，也不知道如何影响这些生物体运输（获取）其他营养物质的能力，进而影响这些生物体的元素组成及其释放有机碳的速率。这很重要，因为海洋蓝藻不仅是全球二氧化碳固定的关键因素，而且由于全球变暖导致海洋环流扩大，预计其数量在未来几年还会增加。因此，了解它们的初级生产力在面对气候变暖时是否会下降、增加或保持不变以及导致这种情况的机制对于预测海洋生态系统功能的未来变化至关重要。因此，在本提案中，我们将确定脂质如何重塑在当前和升高的二氧化碳水平下，生长过程中的磷消耗会影响海洋蓝藻固定二氧化碳、获取关键的大量和微量营养素的能力，从而改变其元素组成。这不仅影响准确的初级生产估计，而且影响这些细胞作为食草动物猎物的营养质量（从而将能量转移到更高的营养水平），反之亦然，当细胞下沉时从水柱中去除的细胞的元素组成 -从而输出 C、N 和 P。我们还将确定氮的限制是否也会引发脂质重塑反应，如果是的话，其后果是什么。获得的所有数据将用于完善当前的生态系统模型公式，描述养分限制对初级生产的影响。考虑到脂质重塑对初级生产的影响的新公式将被实施到欧洲区域海洋生态系统模型（ERSEM）中，从而大大改进了对海洋初级生产的模拟。总的来说，该提案将提供直接估计，并且理解脂质重塑在控制海洋初级生产中的作用的机制基础。随后，数据和概念将在 ERSEM 中使用，以完善海洋光合作用和随后的碳循环的控制点，并最终增强其预测能力。

项目成果

Complementary Approaches to Assess Phytoplankton Groups and Size Classes on a Long Transect in the Atlantic Ocean

评估大西洋长断面浮游植物群和大小等级的补充方法

• DOI: 10.3389/fmars.2021.682621
• 发表时间: 2022
• 期刊: Frontiers in Marine Science
• 影响因子: 3.7
• 作者: Brotas V

Coupling ecological concepts with an ocean-colour model: Phytoplankton size structure

• DOI: 10.1016/j.rse.2022.113415
• 发表时间: 2023-02
• 期刊: Remote Sensing of Environment
• 影响因子: 13.5
• 作者: Xuerong Sun;R. Brewin;S. Sathyendranath;G. Dall’Olmo;R. Airs;R. Barlow;A. Bracher;V. Brotas;M. Kheireddine;T. Lamont;E. Marañón;X. Morán;D. Raitsos;Fang Shen;G. Tilstone

Latitudinal variability and adaptation of phytoplankton in the Atlantic Ocean

大西洋浮游植物的纬度变化和适应

• DOI: 10.1016/j.jmarsys.2022.103844
• 发表时间: 2023
• 期刊: Journal of Marine Systems
• 影响因子: 2.8
• 作者: Barlow R

A compilation of global bio-optical in situ data for ocean colour satellite applications – version three

海洋颜色卫星应用的全球生物光学现场数据汇编 - 第三版

• DOI: 10.5194/essd-14-5737-2022
• 发表时间: 2022
• 期刊: Earth System Science Data
• 影响因子: 11.4
• 作者: Valente, André;Sathyendranath, Shubha;Brotas, Vanda;Groom, Steve;Grant, Michael;Jackson, Thomas;Chuprin, Andrei;Taberner, Malcolm;Airs, Ruth;Antoine, David
• 通讯作者: Antoine, David