Changing Phytoplankton Trace Metal Requirements in a High CO2 Ocean

该奖项是根据2009年《美国复苏和再投资法》(公法111-5)资助的。在过去的二十年里，人们认识到铁和其他具有生物活性的痕量金属在构建海洋食物链和生物地球化学循环方面的根本重要性。最近，在过去几年里，国际海洋科学界已经开始动员起来，紧急努力了解人为二氧化碳增加和全球海洋酸化在生态系统层面造成的后果。这个项目考察了这两个主要研究主题的交集，提出了这样一个问题：海洋浮游植物的微量元素需求将如何随着大气二氧化碳的未来增加而变化？研究人员产生的初步数据表明，二氧化碳的变化确实可以深刻地影响原核和真核浮游植物中Fe、Mo、Zn、Cd、Co和Mn的细胞配额。微量金属在与二氧化碳有效性密切相关的过程中扮演着关键的酶辅助因子的角色，如碳和氮的固定、光合作用的电子传递和养分的获取。因此，在明天快速变化的海洋中，开发定量预测藻类金属需求将如何变化的方法是重要的。调查人员将采取三管齐下的方法来解决这个关键问题。实验室实验将测量关键浮游植物功能群如硅藻、球藻、棕囊藻、重氮和微蓝细菌等稳态培养物的痕量金属配额，同时单独变化二氧化碳，并与铁、温度和光线等其他限制因素一起变化。南加州海湾的实地工作将提供与二氧化碳和其他环境变量相关的季节性周期中自然浮游植物群落的痕量金属化学计量学测量--该地区已经经历了整个西海岸酸性上升水的一些最大增幅。这项观察性和相关性研究将与南加州大学卡塔利纳岛设施的操纵实验相结合，在这些实验中，可以测量同一天然浮游植物群落在受控培养条件下的痕量金属配额与二氧化碳迁移的关系。这三种互补的方法将使研究人员能够在各种时间和空间尺度上确定浮游植物驱动的微量元素生物地球化学在未来高二氧化碳海洋中可能发生的变化。更广泛的影响包括为南加州大学年轻的首席调查员傅(音译)提供一个重要的职业里程碑的机会，以及为未被充分代表的学生提供通过夏季NSF-REU项目、南加州大学高级研究论文项目以及与芝加哥人和美洲原住民科学促进会的新招生计划的机会。该项目的社会和科学影响包括为海洋生物学和生物地球化学对目前人为变化的综合反应提供了新的视角，最终目标是更好地预测未来基本海洋资源的变化和对全球气候的潜在反馈。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Over the past two decades, the fundamental importance of iron and other bioactive trace metals in structuring marine food webs and biogeochemical cycles has been realized. Even more recently, over the past several years, the international ocean science community has begun to mobilize in an urgent effort to understand the ecosystem-level consequences of rising anthropogenic CO2 and acidification of the global ocean. This project examines the intersection of these two major research themes, by asking the question: How will the trace element requirements of marine phytoplankton change in response to future increases in atmospheric pCO2?Preliminary data generated by the investigators suggests that changing pCO2 can indeed profoundly affect the cellular quotas of Fe, Mo, Zn, Cd, Co and Mn in both prokaryotic and eukaryotic phytoplankton. Trace metals play critical roles as enzymatic co-factors for processes that are closely linked to the availability of CO2 such as carbon and nitrogen fixation, photosynthetic electron transport, and nutrient acquisition. Therefore, it is important to develop methods to quantitatively predict how algal metal requirements will change in tomorrow's rapidly changing ocean. The investigators will take a three-pronged approach to addressing this overarching question. Laboratory experiments will measure the trace metal quotas of steady-state cultures of key phytoplankton functional groups like diatoms, coccolithophores, Phaeocystis, and diazotrophic and pico-cyanobacteria while varying pCO2 both alone, and together with other limiting factors such as iron, temperature, and light. Field work in the Southern California bight will provide measurements in trace metal stoichiometry of natural phytoplankton communities over a seasonal cycle in relation to pCO2 and other environmental variables -- this region is already experiencing some of the largest increases in acidic upwelled water along the entire West Coast. This observational and correlative study will be coupled with manipulative experiments at the USC Catalina Island facility in which trace metal quotas of the same natural phytoplankton communities can be measured in relation to pCO2 shifts under controlled incubation conditions. Together, these three complementary approaches will enable the investigators to determine over a variety of temporal and spatial scales how phytoplankton-driven trace element biogeochemistry is likely to change in a future high-CO2 ocean.The broader impacts include providing an opportunity for a major career milestone for young lead investigator Fu, a female minority investigator at USC, as well as opportunities for under-represented students through the summer NSF-REU programs, senior research thesis programs at USC, and a new initiative for student recruitment with the Society for Advancement of Chicanos and Native Americans in Science. The societal and scientific impacts of this project include offering a novel perspective on the integrated responses of ocean biology and biogeochemistry to ongoing anthropogenic change, with the ultimate goal of better predicting future shifts in basic ocean resources and potential feedbacks to global climate.