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

气候导致的变暖预计将增加野火的频率、强度和规模，这可能对环境、人类和经济产生严重影响，特别是在美国西海岸。这些野火导致大量的二氧化碳排放，并将携带营养物质、有机物和微量金属的灰烬沉积到沿海和开阔的海洋上。野火灰烬在海洋上的沉积可以通过给微生物生产施肥或由于重金属毒性抑制微生物生长来改变海洋食物网中的碳和能量流动。灰分的特性（如化学质量、施肥与毒性）和初始微生物群落组成（如多样性、大小分布）如何影响微生物对灰分衍生材料的反应尚不清楚。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。这项工作将促进跨学科的科学，通过产生野火对表面海洋生物学的影响以及从陆地到海洋的碳和能量转移的基础知识，将生物海洋学与陆地生态学和生物地球化学联系起来。该项目的结果将有助于改进对海洋生态系统应对野火变化的预测，这是与依赖海洋生态系统资源（包括渔业）的社区和行业相关的信息。这项工作还将通过解决野火刺激的施肥和海洋中的碳固定是否可以抵消野火产生的二氧化碳排放，为各国减轻和适应气候变化影响的努力提供信息。该项目将为多名本科生提供身临其境的研究体验，并为他们提供通过科学会议和出版物传播其工作成果的机会，从而扩大海洋科学的参与和教育。此外，与该项目相关的为期一天的内容单元将在俄勒冈州立大学每年为期一周的微生物学夏令营中开发和实施，为当地高中生提供微生物学的实践学习经验。具体来说，该项目包括旨在定量描述浮游植物和浮游细菌对各种灰类型的生理反应（例如，生长、生产力、细胞化学计量）的机制研究。从火山灰中浸出的营养物质、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，而这又受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灰的组成所促进或抑制的，并将包括两个主要因素。在第一个元素中，灰将从现场收集，并在实验室中从植物生物质中生成。然后，灰将在海水中浸出，并对其无机和有机物质含量进行化学表征。在第二个要素中，将进行海水培养实验，以量化天然浮游植物和细菌群落对不同灰类型的生理和多样性反应。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向海洋转移的预测模型及其对海洋食物网中碳和能量流动的影响。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

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.