Unravelling the fate of coccolithophores (marine microplankton) during times of rapid environmental change

全球气候系统有许多相互作用的组成部分，本质上是复杂的。在理解当前全球变化方面最具挑战性的任务之一是理清和量化所涉及的组成部分和进程。虽然通过主要将地球视为一个物理或化学系统而成功地模拟了几个过程，但对生物圈中全球变化的定量描述，例如在海洋生态系统中，却远远落后。然而，任何对未来气候变化的评估都需要了解各种自然变异性。因此，拟议的研究项目旨在从根本上了解环境变化如何影响海洋生态系统，特别是球藻，这是一类主要的单细胞海洋浮游植物。球石生物特别令人感兴趣，因为它们作为初级生产者和方解石生产者在海洋碳循环中发挥着重要作用，影响着海洋的二氧化碳水平。据估计，它们贡献了海洋颗粒有机碳固定的46%，以及深海碳酸盐产量的约50%。然而，关于气候的快速变化如何影响球石生物的生产、多样性和进化，目前知之甚少。因此，拟议的研究项目旨在确定球藻生物体如何受到快速环境变化的影响，例如过去200年的人为污染(例如二氧化碳水平增加)、厄尔尼诺南方涛动(ENSO)和来自敏感记录这些快速气候变化的关键地点(例如加利福尼亚州湾、加勒比盆地和阿拉伯海)的季风。特别是，将利用沉积物捕集器和浮游生物样本，分析关键物种，如绿泥虫、海洋巨藻和深水浮游植物的球石生物通量、组合组成和形态变化对环境变化的响应。所获得的数据随后将用于重建和研究全新世期间气候变化对主要地点每年堆积的层状沉积物中的球石生物的影响。应用最新开发的最适合对层状沉积物进行超高分辨率分析的技术和替代方法，保证了高质量的数据；以这种方式获得的知识将对评估未来全球变化对海洋生态系统的影响至关重要。

The global climate system has many interacting components and is inherently complex. One of the most challenging tasks in understanding current global change is the untangling and quantification of the involved components and processes. While several processes have been successfully modeled by treating the Earth mainly as a physical or chemical system, the quantitative characterization of global change in the biosphere, for example in the marine ecosystem, is lagging far behind. However, any assessment of future climate change requires knowledge of the full range of natural variability. Therefore, the proposed research project is designed towards gaining a fundamental understanding of how environmental change affects the marine ecosystem, especially coccolithophores, a major group of single celled marine phytoplankton. Coccolithophores are of particular interest because they play an important part in the marine carbon cycle both as primary producers and calcite producers that affect the CO2 levels of the ocean. They are estimated to contribute 46% of the particulate organic carbon fixation in the ocean, and about 50% of the deep sea carbonate production. However, little is currently known on how rapid climate variability affects the production, diversity and evolution of coccolithophores. Thus, the proposed research project aims to determine how coccolithophores are affected by rapid environmental changes such as anthropogenic pollution during the last 200 years (e.g. increasing CO2 levels), the El Niño Southern Oscillation (ENSO) and Monsoons from key localities that sensitively record these rapid climate changes (e.g., the Gulf of California, the Cariaco Basin, and the Arabian Sea). In particular, the response of coccolithophores flux, assemblage composition and morphological variations of key species such as Emiliania huxleyi, Gephyrocapsa oceanica and Florisphaera profunda to environmental change will be analysed using sediment trap and plankton samples. The obtained data will be subsequently used to reconstruct as well as examine the impact of climate changes during the Holocene on coccolithophores from annually laminated sediments accumulated at the key localities. The application of recently developed techniques and proxies most suitable for ultra high resolution analysis of laminated sediments guarantees high quality data; the knowledge obtained in this way will be essential in assessing the impact of future global change on the marine ecosystem.