The abiotic and biotic factors determining microbial respiration, a key process in ocean carbon storage (MicroRESPIRE)

浮游植物光合作用过程中产生的有机碳与细菌、浮游动物和浮游植物呼吸消耗有机碳之间的平衡决定了海洋中可以储存多少碳，以及大气中有多少碳以二氧化碳的形式存在。海洋中储存的有机碳的数量与大气中二氧化碳的数量一样多，因此也是避免全球气温上升超过1.5摄氏度所需的两个全球碳循环计算的关键组成部分：实现净零碳排放所需的技术和社会努力的计算，以及基于海洋的工程方法直接从大气中去除二氧化碳的效率的计算。然而，尽管海洋碳储存具有至关重要的作用，但我们预测未来海洋碳储存将如何变化的能力受到严重限制，因为我们缺乏对浮游生物呼吸如何随时间和空间变化的了解。它是如何在细菌和浮游动物之间分配的，以及它对气候变化引起的环境条件变化(如气温升高和氧气减少)有多敏感。这种令人遗憾的情况是由于测量深海呼吸的巨大挑战以及这些呼吸数据的归档方式不协调所致。这个项目将直接解决这两个问题。我们将利用我们的领导和参与一个国际方案，该方案部署了数千个海洋浮标来测量全球海洋中的温度、氧气和有机碳，我们将利用一个专注于量化深海微生物呼吸的国际专家小组，以及我们在整理国际数据集方面的经验，制作一个前所未有的细菌和浮游动物呼吸数据集。我们将根据浮标数据得出呼吸估计值，以便与最近开发的包括水下滑翔机在内的方法得出的估计值一起，新数据库将包括在一系列时间和空间尺度上计算的呼吸测量值。至关重要的是，呼吸速率将与温度、氧气和有机碳等同步环境数据相结合。这个数据集将使我们能够量化呼吸的季节和空间变异性，并推导出描述呼吸如何随着细菌和浮游动物的比例以及水的化学和物理性质而变化的方程。然后，这些方程可以用于气候模型，以更好地预测呼吸作用，从而预测未来随着气候变化导致的温度、氧气、有机碳和浮游生物群落的变化，海洋碳储量将如何变化。我们将参加针对发展中国家和发达国家早期职业研究人员的关于深水呼吸观测和模型的混合实践和在线国际培训班，以展示呼吸数据库和全球海洋漂浮物阵列的可用性。我们还将为小学生准备关于在深海观察生命的科学节展览。该项目的成果-一个独特的全球开放的呼吸测量数据库，适用于气候模型的描述呼吸对温度和氧气变化的敏感性的新方程，以及为职业生涯早期研究人员提供的在线培训材料-对旨在预测气候变化将如何影响海洋中的碳储存的科学家、培训下一代海洋科学家和从业人员的教育工作者、需要量化国家对限制全球变暖行动的决心的政策制定者，以及科学家、工程师、律师、管理机构和商业公司设计、评估和实施海洋二氧化碳清除技术。

The balance between the production of organic carbon during phytoplankton photosynthesis and its consumption by bacterial, zooplankton and phytoplankton respiration determines how much carbon can be stored in the ocean and how much remains in the atmosphere as carbon dioxide. The amount of organic carbon stored in the ocean is as large as the amount of carbon dioxide in the atmosphere, and so is a key component in two global carbon cycle calculations needed to avoid a global temperature rise of more than 1.5 degrees C: the calculation of the technological and societal efforts required to achieve net zero carbon emissions and the calculation of the efficiency of ocean-based engineering approaches to directly remove carbon dioxide from the atmosphere.Yet, despite its vital role, our ability to predict how ocean carbon storage will change in the future is severely limited by our lack of understanding of how plankton respiration varies in time and space, how it is apportioned between bacteria and zooplankton and how sensitive it is to climate change-induced shifts in environmental conditions such as increasing temperature and decreasing oxygen. This woeful situation is due to the significant challenge of measuring respiration in the deep-sea and the uncoordinated way in which these respiration data are archived. This project will directly address these two problems. We will take advantage of our leadership and participation in an international programme which deploys thousands of oceanic floats measuring temperature, oxygen and organic carbon in the global ocean, in an international team of experts focused on quantifying deep-sea microbial respiration, and our experience of collating international datasets, to produce an unprecedented dataset of bacterial and zooplankton respiration. We will derive estimates of respiration based on data from floats, so that together with estimates derived from recently developed methods including underwater gliders, the new database will include respiration measurements calculated over a range of time and space scales. Crucially, respiration rates will be coupled with concurrent environmental data such as temperature, oxygen and organic carbon. This dataset will enable us to quantify the seasonal and spatial variability of respiration and derive equations describing how respiration changes with the proportion of bacteria and zooplankton present and with the chemical and physical properties of the water. These equations can then be used in climate models to better predict how respiration and therefore ocean carbon storage will change in the future with climate-change induced shifts in temperature, oxygen, organic carbon and plankton community. We will take part in a hybrid hands-on and online international training course on observations and models of deep-water respiration targeted to early career researchers from developing and developed countries to showcase the useability of the respiration database and the global array of oceanic floats. We will also prepare Science Festival exhibits on observing life in the deep ocean for schoolchildren.The deliverables of the project - a unique global open-access database of respiration measurements, new equations describing the sensitivity of respiration to changing temperature and oxygen suitable for climate models and online training materials for early career researchers - are of benefit to scientists who aim to predict how a changing climate will affect the storage of carbon in the ocean, educators who train the next generation of ocean scientists and practitioners, policy makers who need to quantify nationally determined contributions to actions limiting global warming, and scientists, engineers, lawyers, governing bodies and commercial companies designing, evaluating and implementing ocean-based carbon dioxide removal technologies.