Planktonic interactions in a changing ocean: Biological responses of Emiliania huxleyi to elevated pCO2 and their effects on microzooplankton

钙化的异形植物艾米莉亚·赫克斯莱伊似乎对海洋二氧化碳浓度的上升非常敏感。E.huxleyi记录的对二氧化碳升高的反应包括改变其钙化率和细胞大小、球石畸形、生长速度提高、有机碳产量增加、PIC/POC比率降低以及活性气候气体DMS产量增加。这些参数的变化是已知的引起微型浮游动物放牧行为改变的机制，微型浮游动物是海洋中占主导地位的食草动物功能群。研究人员假设，对钙化和非钙化超植物埃米莉亚·Huxleyi的生理和生化进行修改，以响应二氧化碳的增加，将导致微型浮游动物觅食动力学的变化。为了验证这一假设，他们将进行受控实验室实验，在几个二氧化碳浓度下生长几个菌株。在仔细描述了E.huxleyi菌株对二氧化碳浓度升高的生化和生理反应后，他们将把这些菌株作为几种具有生态重要性的微型浮游动物的食物，并记录放牧动态。Huxleyi是研究浮游植物和微型浮游动物对人为CO2增加的响应的理想生物，其在海洋环境中的影响被称为海洋酸化；E.huxleyi具有重要的生物地球化学意义，研究得很好，培养的许多菌株显示出上述参数的变化，它们很容易被具有生态意义的重要微型浮游动物摄食。赫克斯莱伊是一种模式捕食性生物，因为它是最具生物地球化学影响的全球浮游植物之一。它形成了大规模的季节性水华，对海洋无机和有机碳循环做出了重大贡献，是气候活跃的气体DMS的主要生产者，也是自身上下营养水平的有机物质来源。计划中的对照研究将增加我们对驱动营养水平之间变化模式的机制的知识，从而提供更广泛的工具，以了解海洋酸化现场研究的复杂性质，其中相互竞争的变量可能会混淆准确的解释。广泛的影响该研究项目将为两名职业生涯早期的科学家、一名研究生和许多本科生提供支持。本科生的参与将主要来自SPMC的两个长期驻留项目：获奖的海洋科学多元文化倡议：本科生参与(MIMSUP)和本科生研究经历(REU)。MIMSUP计划的使命是通过课程和研究增加下一代海洋科学家的多样性。参加MIMSUP的学生开展独立的研究项目，出席国内和国际会议，并开展社区外联活动。REU计划为我们的研究提供了接触全国受众的门户；就在去年，SPMC收到了来自90所不同大学的118份REU申请。WWUS生物系和环境科学系的本科生也将通过PI项目教授的课程参与这项研究。最后，该中心已获得资金，聘请了一名K-12外联协调员，该协调员将开展一系列讲习班、公开讲座和演讲，并对K-12课程做出贡献。这项研究的结果将纳入所有这些外展工作。

The calcifying Haptophyte Emiliania huxleyi appears to be acutely sensitive to the rising concentration of ocean pCO2. Documented responses by E. huxleyi to elevated pCO2 include modifications to their calcification rate and cell size, malformation of coccoliths, elevated growth rates, increased organic carbon production, lowering of PIC:POC ratios, and elevated production of the active climate gas DMS. Changes in these parameters are mechanisms known to elicit alterations in grazing behavior by microzooplankton, the oceans dominant grazer functional group. The investigators hypothesize that modifications to the physiology and biochemistry of calcifying and non-calcifying Haptophyte Emiliania huxleyi in response to elevated pCO2 will precipitate alterations in microzooplankton grazing dynamics. To test this hypothesis, they will conduct controlled laboratory experiments where several strains of E. huxleyi are grown at several CO2 concentrations. After careful characterization of the biochemical and physiological responses of the E. huxleyi strains to elevated pCO2, they will provide these strains as food to several ecologically-important microzooplankton and document grazing dynamics. E. huxleyi is an ideal organism for the study of phytoplankton and microzooplankton responses to rising anthropogenic CO2, the effects of which in the marine environment are called ocean acidification; E. huxleyi is biogeochemically important, is well studied, numerous strains are in culture that exhibit variation in the parameters described above, and they are readily fed upon by ecologically important microzooplankton.Intellectual MeritThe implications of changes in microzooplankton grazing for carbon cycling, specifically CaCO3 export, DMS production, nutrient regeneration in surface waters, and carbon transfer between trophic levels are profound, as this grazing, to a large degree, regulates all these processes. E. huxleyi is a model prey organism because it is one of the most biogeochemically influential global phytoplankton. It forms massive seasonal blooms, contributes significantly to marine inorganic and organic carbon cycles, is a large producer of the climatically active gas DMS, and is a source of organic matter for trophic levels both above and below itself. The planned controlled study will increase our knowledge of the mechanisms that drive patterns of change between trophic levels, thus providing a wider array of tools necessary to understand the complex nature of ocean acidification field studies, where competing variables can confound precise interpretation.Broader ImpactsThis research project will provide support for two early-career scientists, a graduate student, and numerous undergraduate students. Undergraduate student involvement will come largely from SPMCs long-standing two resident programs: the award-winning Multicultural Initiative in the Marine Sciences: Undergraduate Participation (MIMSUP) and Research Experience for Undergraduates (REU). The mission statement of the MIMSUP program is to increase diversity within the next generation of marine scientists through coursework and research. Students participating in MIMSUP conduct independent research projects, present at national and international meetings, and conduct community outreach. The REU program provides the portal for our research to reach a nation-wide audience;just last year SPMC received 118 REU applications representing 90 different universities. Undergraduates from WWUs Biology and Environmental Science departments will also participate in this research through courses taught by the project PIs. Finally, SPMC has received funding to hire a K-12 outreach coordinator who will develop a series of workshops, public lectures and presentations, and contributions to K-12 curriculum. Findings from this research will be incorporated into all of these outreach efforts.