Empirical determination of the interaction landscape for temperature, CO2 and nitrate for a model diatom

硅藻模型温度、CO2 和硝酸盐相互作用景观的实证测定

• 批准号: NE/X001237/1
• 负责人: Sinead Collins
• 金额: $ 80.4万
• 依托单位: University of Edinburgh
• 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%2FX001237%2F1
• 关键词: Empirical; determination; interaction; landscape; temperature

Phytoplankton are the small but mighty single-celled photosynthetic organisms that form the base of most aquatic food webs, affect nutrient cycles, and are responsible for approximately half of the carbon fixation on Earth. Among the phytoplankton, diatoms are responsible for about 40% of marine primary production, which is up to 20% of global production, and are believed to be responsible for approximately 40% of global carbon export, some of which is sequestered in the deep ocean. At mid and high latitudes, such as around the UK, they increase the trophic efficiency of marine foodwebs, providing a direct link between primary production, grazers, and larger marine animals. The ocean environment where diatoms live is changing rapidly through warming, increases in CO2, and decreases in the nutrient levels (particularly nitrogen) in the upper part of the ocean where photosynthesis occurs. We have a reasonably good understanding of how phytoplankton react to these environmental changes in isolation. At high latitudes at least, increases in temperature and CO2 increase phytoplankton growth, whereas decreases in nitrogen availability decreases growth. Surprisingly, though, there is little experimental data on how phytoplankton react to all of these things changing simultaneously. Recent studies show that it is important to consider environmental changes together, as the organismal responses to several changes at once is not predictable from the organismal responses to each of the changes alone. For example, not only does lower nitrogen decrease the overall population size that diatoms can achieve, but it also makes them more sensitive to high temperatures, so that the effects of ocean warming may be exacerbated by nutrient limitation. In addition, we have data from other phytoplankton that suggest that elevated CO2 can partially mitigate negative effects of some other environmental changes, but we don't know if this applies to diatoms. Despite the importance of diatoms in marine ecosystems, there are very few experiments that enable us to understand, in a generalisable way, how diatoms respond to temperature, nitrate, and CO2 all changing at once. This, when combined with uncertainty in predictions about future ocean conditions themselves, means that currently, we are not even able to project whether global primary production is expected to increase or decrease over the coming decades. This uncertainty makes is harder to accurately project ecosystem services including the potential for carbon export in oceans. Our research uses laboratory experiments to learn how simultaneous changes in temperature, nitrate, and CO2 levels affect diatom growth and the physiology that underlies it. Our experiments are designed to test and choose between general equations describing how fundamental, conserved growth processes are affected under multiple simultaneous environmental changes. We will then use our empirical findings to explore how interactions between environmental changes affect future projections of diatom spatial distributions and growth in a widely-used global marine ecosystem model. The project as a whole will improve our ability to project changes to phytoplankton growth in the oceans, which can then improve projections of climate and ecosystem services, as well as our understanding of how the largest ecosystem on earth functions.

浮游植物是构成大多数水生食物网的基础的小型但强大的单细胞光合生物，影响营养周期，并负责大约一半的地球碳固定。在浮游植物中，硅藻约有40％的海洋初级产量，该生产占全球生产的20％，据信造成约40％的全球碳出口，其中一些是在深海中隔离的。在英国各地的中纬度地区和高纬度地区，它们提高了海洋食品的营养效率，从而在初级生产，放牧者和较大的海洋动物之间提供了直接联系。硅藻活着的海洋环境正在通过变暖，二氧化碳增加以及在光合作用的海洋上部的养分水平（尤其是氮）迅速变化。我们对浮游植物对这些环境变化的反应有相当的了解。至少在高纬度下，温度和二氧化碳的升高增加了浮游植物的生长，而氮的可用性降低会降低生长。但是，令人惊讶的是，关于浮游植物如何同时改变所有这些事情的反应几乎没有实验数据。最近的研究表明，重要的是要将环境变化一起考虑，因为从单独的变化的有机体反应中，对几种变化的有机体反应是无法预测的。例如，较低的氮不仅减少了硅藻可以实现的总体种群大小，而且还使它们对高温更敏感，从而使海洋变暖的影响可能会因营养限制而加剧。此外，我们还有来自其他浮游植物的数据，表明升高的二氧化碳可以部分减轻其他环境变化的负面影响，但我们不知道这是否适用于硅藻。尽管硅藻在海洋生态系统中很重要，但很少有实验使我们能够以普遍的方式理解硅藻对温度，硝酸盐和二氧化碳的响应如何立即改变。这是在对未来海洋状况本身的预测中的不确定性结合在一起时，这意味着目前，我们甚至无法预期在未来几十年中全球初级产量是否会增加或减少。这种不确定性使得很难准确地投影生态系统服务，包括海洋中碳出口的潜力。我们的研究使用实验室实验来了解温度，硝酸盐和二氧化碳水平的同时变化会影响硅藻生长以及其基础的生理学。我们的实验旨在在一般方程式之间进行测试和选择，描述了基本，保守的生长过程如何在多个同时环境变化下影响。然后，我们将利用经验发现来探讨环境变化之间的相互作用如何影响广泛使用的全球海洋生态系统模型中硅藻空间分布和增长的未来预测。整个项目将提高我们对海洋中浮游植物增长的变化的能力，然后可以改善气候和生态系统服务的预测，以及我们对地球上最大的生态系统的理解。