How does intensity and frequency of environmental variability affect phytoplankton growth?

被称为浮游植物的微型植物是全球海洋生态系统的关键成员，因为它们的光合作用支持大部分海洋食物链，并产生与陆地植物一样多的氧气。 因此，海洋学家经常进行实验，研究温度和二氧化碳水平等因素如何影响浮游植物的生长。 以前的大多数实验都使用恒定的温度和二氧化碳水平，但从真实的海洋生态系统的测量结果来看，这两个因素在几天到几周的时间尺度上变化很大。 利用现场和实验室实验沿着计算机建模，该项目将测试在温度和二氧化碳恒定的条件下，与这些因素在强度和频率上波动的条件相比，浮游植物的几个主要群体的生长有何不同。这项研究将使海洋科学家更好地了解浮游植物如何应对当今和未来不断变化的自然环境，从而帮助我们了解海洋食物网如何支持渔业等关键生物资源。 该项目将培训研究生和本科生以及一名博士后研究员，首席科学家将参与一个海洋科学教育项目，该项目主要面向洛杉矶市中心学区的少数民族高中生。该项目的目标是利用实验室培养和自然群落实验，了解温度和二氧化碳分压条件如何真实地影响全球重要的浮游植物群体，方法不同于以往工作中使用的人工恒定曝光。 培养实验将测试短期热和碳酸盐波动的强度和频率如何影响重氮和picoprotonic蓝藻，颗石藻和硅藻在当前和预测的未来环境条件下的生长反应。 这些实验室的结果将支持和扩展的平行实验，使用混合的自然组合从加州的上升流制度，使我们能够测试这些相同的问题，使用浮游植物群落，经历大的季节性变化之间的高度动态的热和碳酸盐系统的条件下，在春季上升流季节，和相对更静态的条件下，在秋季分层事件。 这些结果将使用新一代的数值模型进行合成，这些模型采用新的方法来结合现实的环境变化，以便更准确地预测浮游植物对当今海洋生态系统中动态环境的反应，以及未来不断变化的海洋。

Microscopic plants called phytoplankton are key members of global oceanic ecosystems, since their photosynthesis supports the majority of the marine food chain and produces about as much oxygen as land plants. Because of this, oceanographers have often carried out experiments examining how factors such as temperature and carbon dioxide levels may affect phytoplankton growth. Most previous experiments have used constant levels of temperature and carbon dioxide, but it is clear from looking at measurements from real ocean ecosystems that these two factors often vary greatly over timescales of days to weeks. Using field and laboratory experiments along with computer modeling, this project will test how the growth of several major groups of phytoplankton differs under constant conditions of temperature and carbon dioxide, compared to conditions in which these factors fluctuate in intensity and frequency. This research will give marine scientists a better picture of how phytoplankton may respond to a varying natural environment today and in the future, and therefore help us to understand how ocean food webs function to support critical living resources such as fisheries. The project will train graduate and undergraduate students and a postdoctoral researcher, and the lead scientists will be involved in an ocean science education program for largely minority high school students from a downtown Los Angeles school district.The goal of this project is to use laboratory culture and natural community experiments to understand how realistically fluctuating temperature and pCO2 conditions may affect globally important phytoplankton groups in ways that differ from the artificial constant exposures used in previous work. Culture experiments will test how the intensity and frequency of short-term thermal and carbonate fluctuations affects the growth responses of diazotrophic and picoplanktonic cyanobacteria, coccolithophores, and diatoms under both current and projected future environmental conditions. These lab results will be supported and extended by parallel experiments using mixed natural assemblages from the California upwelling regime, allowing us to test these same questions using phytoplankton communities that experience large seasonal shifts between highly dynamic thermal and carbonate system conditions during the spring upwelling season, and relatively much more static conditions during fall stratification events. These results will be synthesized using a new generation of numerical models that employ novel approaches to incorporating realistic environmental variations to allow more accurate predictions of phytoplankton responses to a dynamic environment in today's marine ecosystems, and in the future changing ocean.