Collaborative Research: ORCC: Carbon fixation in future oceans: experimental adaptation of algal and cyanobacterial CO2-concentrating mechanisms to a changing climate

光合作用海洋微生物，或浮游植物，使用二氧化碳来建立其生物量。当浮游植物死亡并下沉时，它们将这些碳转移到深海，使其与大气隔离。这一过程被称为生物泵，通过吸收人类活动产生的二氧化碳，缓解了气候变化的影响。生物泵的效率--以及海洋在未来持续吸收二氧化碳的能力--将取决于不同浮游植物群体适应气候变化影响（如变暖和酸化）的能力。为了量化亚细胞过程的累积效应将如何决定未来海洋中浮游植物使用的二氧化碳量，本研究测试了不同浮游植物群体对2100年和2500年海洋预期条件的适应性。本项目将培养一名博士后研究员，一名博士生。该项目包括一名学生、四名暑期本科实习生，并与一名资深科学家合作，支持一名女性、首次调查员和早期职业研究员的职业发展。这项工作将通过国家指导计划的运作和改进来促进社会挑战的创新解决方案，该计划旨在通过为有兴趣攻读气候和地球科学研究生学位的学生提供导师来支持他们的职业发展，从而增加气候相关领域的多样性。当今海洋中的碳固定通过CO2浓度机制（CCM）进行，该机制通过增加碳固定地点的CO2浓度来提高碳固定的效率。CCM在不同的浮游植物群体中独立进化，导致具有趋同功能的不同类型的CCM。持续的人为二氧化碳排放迫使浮游植物以更快的速度适应气候变化的影响。已知CCM的各个成分会对气候变化的影响做出反应，包括pH值，溶解无机碳的浓度和温度。CCM在亚细胞水平上的累积响应代表了浮游植物对气候变化的有机体响应，直接影响了未来海洋的固碳效率。该项目的主要目标是量化CCM的适应性反应，通过实验进化的五个浮游植物群体与不同的CCM，包括硅藻，甲藻，绿色藻，颗石藻，和蓝藻的气候变化的选择性驱动程序。具体项目目标包括：1）量化相关海洋浮游植物对多个“2100年”气候变化压力源的可塑性和适应性固碳反应; 2）量化相关海洋浮游植物在极端气候条件下对多个气候变化压力源的可塑性和适应性固碳反应。（“2500年”）情况;以及3）解决亚细胞组分如何对构成生态系统基础的浮游植物的有机CCM响应做出贡献-该奖项反映了NSF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。

Photosynthetic marine microorganisms, or phytoplankton, use carbon dioxide to build their biomass. When phytoplankton die and sink, they transfer this carbon to the deep ocean, sequestering it away from the atmosphere. This process, known as the biological pump, has tempered the effect of climate change through the absorption of anthropogenic carbon dioxide. The efficiency of the biological pump – and the ocean’s continued ability to absorb carbon dioxide in the future – will depend on the ability of different phytoplankton groups to adapt to effects of climate change, such as warming and acidification. In order to quantify how the cumulative effects of subcellular processes will determine the amount of carbon dioxide phytoplankton use in future oceans, this research tests the adaptability of different phytoplankton groups to the expected conditions in year 2100 and year 2500 oceans. This project will train a postdoctoral researcher, a Ph.D. student, four summer undergraduate interns, and support the professional development of a female, first-time investigator, and early career researcher in collaboration with a senior scientist. The work will promote innovative solutions to societal challenges through the operation and improvement of a national mentoring program designed to increase diversity in climate related fields by providing students interested in pursuing graduate degrees in climate and Earth sciences with mentors to support their career development. Carbon fixation in today’s oceans proceeds through CO2-concentration mechanisms (CCMs) that improve the efficiency of carbon fixation by increasing CO2 concentrations at site of carbon fixation. CCMs have evolved independently within different groups of phytoplankton resulting in distinct types of CCMs with convergent functions. Continued anthropogenic CO2 emissions are forcing phytoplankton to adapt to the impacts of climatic change at an accelerating pace. Individual components of CCMs are known to respond to the effects of climate change including pH, the concentration of dissolve inorganic carbon, and temperature. The cumulative response of CCMs at the subcellular level represents the organismal response of phytoplankton to climate change, with direct implications for the efficiency of carbon fixation in future oceans. The primary goal of this project is to quantify the adaptive response of CCMs to the selective drivers of climate change through the experimental evolution of five phytoplankton groups with distinct CCMs, including a diatom, dinoflagellate, green alga, coccolithophore, and a cyanobacterium. Specific project objectives include 1) quantify the plastic and adaptive carbon fixation response of relevant marine phytoplankton to multiple ‘year 2100’ climate change stressors; 2) quantify the plastic and adaptive carbon fixation response of relevant marine phytoplankton to multiple climate change stressors in an extreme (‘year 2500’) scenario; and 3) resolve how the subcellular components contribute to the organismal CCM response of phytoplankton that underlies the ecosystem-scale impact of carbon fixation in future oceans.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.