The heat is on: resilience and tipping points in Arctic phytoplankton populations under climate change induced heatwaves

气候变化及其相关极端事件对初级生产力的影响对生态系统功能和生物地球化学循环极为重要。在未来的气候中，海洋热浪预计将在全球范围内增加频率和强度，特别是在高纬度地区。然而，研究应对这类事件的潜在生态机制及其对初级生产者的影响的严格方法仍然非常有限。该项目旨在通过三个相互交织的工作包阐明北极浮游植物对短期变暖事件的适应能力和限度，重点是实验室实验、实地观察和改进新的方法。对变化的环境条件的调整可以通过在几个基本生态水平(基因、种群和物种群落)上的生理和进化反应来进行，特别是在原生生物中，这些因素极其难以分离。最大的挑战之一是分析种内多样性和动态，这将是本项目的特别重点。使用一种新的方法来有效地检查原生生物种群的组成(微卫星PoolSeq条形码)，再加上有针对性的实验和北极峡湾连续六年的独特环境时间序列，我将努力弥合这些关于快速生理和进化适应热浪的实质性知识差距。实验数据和观测数据的直接结合是一种新的和必要的方法，可以使简化的设置中的测量更适用于“真实世界”的情况。这些实验的目的是在可比较的设置中，在几个级别的生态复杂性(从实验室单一栽培到自然田野群落)上分离热浪响应，并将提供与生态模型应用直接相关的结果。

Effects of climate change and associated extreme events on primary productivity are of paramount interest for ecosystem functioning and biogeochemical cycling. In a future climate, marine heatwaves are forecasted to increase globally in frequency and intensity, especially in high-latitude regions. Yet, rigorous approaches to investigate underlying ecological mechanisms in the response to such events and their implications for primary producers are still very limited. This project aims at elucidating the adaptive capacity and limits of Arctic phytoplankton towards short warming events within three intertwined work packages focusing on laboratory experiments, field observations and refinement of novel methodology. Adjustments to changed environmental conditions can take place through physiological and evolutionary responses on several fundamental ecological levels (genotype, population and species community), which are especially in protists extremely difficult to disentangle. One of the largest challenges is the analysis of intraspecific diversity and dynamics, which will be the special focus of this project. Using a novel approach to efficiently examine the composition of protist populations (Microsatellite PoolSeq Barcoding), along with targeted experiments and a unique environmental time-series across six consecutive years from an Arctic fjord, I will work towards closing these substantial knowledge gaps on rapid physiological and evolutionary adjustments to heatwaves. The direct combination of experimental and observational data is a novel and necessary approach to making measurements in simplified setups more applicable to the ‘real world’ situation. The experiments are designed to disentangle heatwave responses at several levels of ecological complexity (from laboratory monocultures to natural field communities) in comparable set-ups, and will provide outcomes directly relevant for application in ecological models.