Postdoctoral Fellowship: OCE-PRF: Smoke on the water: the impacts of wildfire ash deposition on surface ocean biology

气候驱动的变暖预计将增加野火的频率，强度和规模，这可能会对环境，人类和经济产生严重影响，特别是沿着美国西海岸。这些野火导致大量的二氧化碳排放和灰烬沉积，携带营养物质，有机物质和微量金属到沿海和公海上。野火灰烬在海洋上的沉积可以通过减少微生物的生产或由于重金属毒性而抑制微生物的生长来改变海洋食物网中的碳和能量流动。灰的性质（例如，化学质量，无毒性）和起始微生物群落组成（例如，多样性、尺寸分布）影响微生物对灰衍生材料的反应是未知的。该项目将通过调查美国西海岸海洋浮游生物对当地野火和植物生物量产生的不同类型灰烬的生理反应来解决这一知识差距。这项工作将推进跨学科科学，通过产生野火对海洋表面生物学以及从陆地到海洋的碳和能量转移的影响的基础知识，将生物海洋学与陆地生态学和海洋地球化学联系起来。该项目的成果将有助于更好地预测海洋生态系统因野火而发生的变化，这是与依赖海洋生态系统资源（包括渔业）的社区和行业有关的信息。这项工作还将为各国减轻和适应气候变化影响的努力提供信息，方法是解决野火刺激的海洋施肥和碳固定是否可以抵消野火造成的二氧化碳排放。该项目将扩大海洋科学的参与和教育，为多名本科生提供身临其境的研究体验，并为他们提供机会，通过科学会议和出版物传播他们的工作。此外，俄勒冈州州立大学每年举办为期一周的微生物夏令营，将开发和实施与该项目相关的为期一天的内容单元，为当地高中生提供微生物方面的实践学习经验。具体而言，该项目包括旨在定量描述生理反应的机制研究（例如，生长、生产力、细胞化学计量学）的浮游植物和浮游细菌的各种灰类型。从火山灰中浸出到海水中的营养物质、有机物和微量金属的数量和比例可能取决于火山灰的质量，而火山灰的质量又受到植被类型和火山灰产生时的温度的影响。这项研究将评估微生物的生产和生长是如何被火山灰的成分所滋养或抑制的，它将由两个主要元素组成。在第一个元素中，灰烬将从野外收集，并在实验室中从植物生物质中产生。然后将灰在海水中浸提，并对无机物和有机物含量进行化学表征。在第二个要素中，将进行海水培养实验，以量化自然存在的浮游植物和细菌群落对不同类型火山灰的生理反应和基于多样性的反应。该项目产生的数据将有助于改进野火驱动的物质从陆地系统转移到海洋的预测模型及其对海洋食物网中碳和能量流的影响。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

Climate-driven warming is projected to increase the frequency, intensity, and size of wildfires that can have severe environmental, human, and economic impacts, particularly along the U.S. West Coast. These wildfires result in dramatic CO2 emissions and deposition of ash carrying nutrients, organic matter, and trace metals onto the coastal and open ocean. Deposition of wildfire ash on the ocean can alter the carbon and energy flow through marine food webs by fertilizing microbial production or inhibiting microbial growth due to heavy metal toxicity. How the character of both the ash (e.g., chemical quality, fertilizing v. toxic) and the starting microbial community composition (e.g., diversity, size distribution) influences the microbial response to ash-derived material is unknown. This project will address this knowledge gap by investigating the physiological responses of marine plankton off the U.S West Coast to different types of ash generated from local wildfires and plant biomass. This work will advance interdisciplinary science, bridging biological oceanography with terrestrial ecology and biogeochemistry, by generating foundational knowledge of wildfire impacts on surface ocean biology and carbon and energy transfer from land to ocean. Results from this project will enable improved forecasts of changes in marine ecosystems in response to wildfires, which is information pertinent to communities and industries that depend on ocean ecosystem resources, including fisheries. The work will also inform national efforts to mitigate and adapt to the impacts of climate change by addressing whether wildfire-stimulated fertilization and carbon fixation in the ocean can offset CO2 emissions from wildfires. This project will broaden participation and education in ocean science by providing immersive research experiences for multiple undergraduate students and opportunities for them to disseminate their work through scientific conferences and publications. Additionally, a day-long content unit related to the project will be developed and implemented in Oregon State University’s annual week-long Microbiology Summer Camp, which provides local high school students with a hands-on learning experience in microbiology.Specifically, this project consists of mechanistic studies designed to quantitatively describe the physiological responses (e.g., growth, productivity, cellular stoichiometry) of phytoplankton and bacterioplankton to a variety of ash types. The quantity and proportion of nutrients, organic matter, and trace metals leached from ash into seawater likely depends on the quality of the ash, which is influenced by vegetation type and the temperature at which the ash was produced. This study will assess how microbial production and growth are fertilized or inhibited by the composition of ash and will consist of two primary elements. In the first element, ash will be collected from the field and generated in the lab from plant biomass. The ash will then be leached in seawater and chemically characterized for inorganic and organic matter content. In the second element, seawater incubation experiments will be conducted to quantify physiological and diversity-based responses of naturally occurring phytoplankton and bacterial communities to different ash types. Data generated from this project will contribute to improved predictive models of wildfire-driven material transfer from the terrestrial system to the ocean and its impact on carbon and energy flow in marine food webs.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.