Future global ocean carbon storage: Quantifying warming impacts on zooplankton (C-QWIZ)

海洋中被称为浮游植物的微生物利用太阳的能量将二氧化碳、营养物质和水转化为有机物，就像陆地上的植物一样。这种有机物质是浮游动物的食物，它们在全球海洋中随处可见。海洋浮游动物是如此丰富，以至于它们全球种群的总重量远远超过了今天地球上约80亿人的总重量。像所有的动物一样，浮游动物会产生大量的粪便，并将其排入周围的环境中。其中一些废物沉入深渊，携带着曾经在大气中以二氧化碳形式存在的碳。任何到达深海的粪便碳都可能被锁在那里100年甚至1000年。以这种方式输出碳的过程规模如此之大，以至于它在全球气候调节中起着至关重要的作用，通过减缓二氧化碳在大气中积聚的速度，使我们的星球保持凉爽。浮游动物是冷血动物，因此，它们的生理速率随着环境变暖而增加。相比之下，浮游动物的体型随着变暖而减小，尽管这一现象背后的机制尚不清楚。事实上，我们对温度如何影响浮游动物生理的理解还有很多空白。例如，随着气候变暖，它们捕获食物的速度是否与它们对能源需求的增长速度相同？如果是这样，也许他们会简单地通过吃来摆脱气候危机？但如果没有呢？持续的海洋变暖可能会导致浮游动物不得不消耗越来越多的食物来满足温度导致的能量需求的增加，而留给生长和繁殖的食物越来越少。如果浮游动物可获得的食物数量随着海洋变暖而减少，这种情况会变得更糟吗？不同体型的个体对温度的反应不同吗？我们对温度、食物供应和浮游动物体型之间的相互作用了解不完全，这意味着我们无法可靠地预测它们对海洋变暖的反应。事实上，大多数用于预测未来气候的全球海洋生态系统模型都假设浮游动物生理学的这些方面是固定的，对变暖不敏感。因此，随着整个21世纪海洋变暖，我们对预测浮游动物通过海洋碳储存对全球气候调节的贡献将如何变化的能力信心有限。我们的项目C-QWIZ将确定不同大小的浮游动物在不同食物水平下对温度升高的反应。通过这样做，我们将填补我们对它们对气候变化的生理反应的基本理解中的许多知识空白。C-QWIZ团队具有独特的优势，可以将这一新认识转化为现有的全球海洋生态系统数学模型；我们将是第一个机械地评估全球变暖如何影响整个21世纪浮游动物介导的海洋碳储存的人。我们选择的模型被世界各地的科学家用来预测地球未来的气候变化。这些预测被政治家和政策制定者用来决定如何最好地管理我们星球的未来。因此，改进这些模型可以确保我们的科学为整个社会带来真正和持久的变化。

Microscopic organisms in the ocean called phytoplankton use the sun's energy to convert carbon dioxide (CO2), nutrients and water into organic matter, just as plants do on land. This organic matter is grazed upon by tiny animals called zooplankton that are found throughout the global ocean. Marine zooplankton are so abundant that the total weight of their global population greatly exceeds that of the ~8 billion humans alive on Earth today. Like all animals, zooplankton produce vast quantities of faecal matter that they eject into the surrounding environment. Some of this waste sinks down into the abyss, carrying with it carbon that was once in the atmosphere as CO2. Any faecal carbon that reaches the deep ocean may be locked away down there for 100's or even 1000's of years. The process of exporting carbon in this way occurs on such a scale that it plays a fundamental role in global climate regulation, keeping our planet cool by slowing the rate at which CO2 accumulates in our atmosphere. Zooplankton are cold-blooded, and as such, their physiological rates increase as their environment warms. By contrast, the body size of zooplankton decreases with warming, although the mechanism underlying this phenomenon remains uncertain. Indeed, there are many gaps in our understanding of how temperature affects zooplankton physiology. For example, does the rate at which they can capture food increase at the same rate at which their demand for energy increases with warming? If it does, perhaps they will simply eat their way out of the climate crisis? But what if it doesn't? Continued ocean warming may then result in zooplankton having to use more and more of their food to meet the temperature-driven increase in their energy demands, leaving less and less for growth and reproduction. Does this situation get worse if the amount of food available to zooplankton decreases with ocean warming? And do different sized individuals respond differently to temperature? Our incomplete understanding of the interplay between temperature, food supply and zooplankton body size means that we cannot reliably predict their response to ocean warming. Indeed, most global models of the ocean ecosystem that are used to help predict future climate assume that these aspects of zooplankton physiology are fixed, with no sensitivity to warming. We therefore have only limited confidence in our ability to forecast how the zooplankton contribution to global climate regulation via ocean carbon storage will change as the ocean warms throughout the 21st century.Our project, C-QWIZ, will determine how zooplankton of different sizes respond to increasing temperatures at different levels of food. In doing so, we will fill many of the knowledge gaps in our fundamental understanding of their physiological response to climate change. The C-QWIZ team is uniquely placed to translate this new understanding into existing mathematical models of the global ocean ecosystem; we will be the first to mechanistically assess how global warming affects zooplankton-mediated ocean carbon storage throughout the 21st century. Our chosen model is used by scientists around the world to forecast how Earth's future climate will change. These forecasts are used by politicians and policy makers to decide on how best to manage the future of our planet. Improving these models therefore ensures that our science delivers real and lasting change for the benefit of all society.