GLOBEC Primary Productivity and Mesoscale Variability

最近在加州海流的研究表明，至少有两种类型的生态/生理策略。近岸社区（占主导地位的大型链形成和中心硅藻）可能会采取非平衡策略，利用物理破坏的环境。例如，它们利用光的能力比它们获取光的能力变化得更快，这意味着它们可能会对光和养分供应等物理强迫的变化做出快速反应。离岸社区（占主导地位的小鞭毛虫）遵循平衡策略，光收集和利用几乎平衡。研究人员假设，非平衡群落更有利于高营养水平，如磷虾和幼鲑，中尺度变化模式的时空变化将决定非平衡群落的范围。研究人员将利用浮游植物生理学的快速测量和物理环境的详细测量相结合。研究人员将利用生物光学漂移仪跟踪布兰科角北部和南部的中尺度特征，同时进行详细的荧光测量。这些将包括快速重复率荧光测定法（FRRF）和下行辐射和上行辐射的光谱测量，包括太阳激发荧光。 这些现场观测结果将与下一代海洋颜色传感器（中分辨率成像光谱仪）的数据进行比较，后者将测量叶绿素荧光效率。这些测量将集中在五个基本问题：1。 初级生产力的可变性尺度是什么？这些尺度与物理过程有什么关系？2. 布兰科角北部和南部的中尺度变率和初级生产力的模式是如何变化的？3. 在上升流季节，中尺度变率和生产力之间的关系如何随季节变化？ 4. 在近岸区，光和营养盐对浮游植物生产力的相对重要性是什么？和5. 浮游植物在一个特征中保留了多长时间？在确定浮游植物现存量时，原地生长与平流/辐合的相对重要性是什么？

Recent studies in the California Current suggest that there are at least two types of ecological/physiological strategies. The nearshore community (dominated by large chain-forming and centric diatoms) may pursue a non-equilibrium strategy to exploit a physically-disrupted environment. For example, their ability to utilize light varies much more rapidly than their ability to harvest light, implying that they may respond rapidly to changes in physical forcing such as light and nutrient availability. The offshore community (dominated by small flagellates) follows an equilibrium strategy with light harvesting and utilization nearly in balance. The researchers hypothesize that the non-equilibrium community is more favorable for higher trophic levels such as euphausiids and hence juvenile salmon, and that spatial and temporal changes in the patterns of mesoscale variability will govern the extent of the non-equilibrium community. The researchers will use rapid measurements of phytoplankton physiology in conjunction with detailed measurements of the physical environment.The investigators will track mesoscale features north and south of Cape Blanco, using bio--optical drifters, while making detailed fluorometric measurements. These will include Fast Repetition Rate Fluorometry (FRRF) and spectral measurements of downwelling irradiance and upwelling radiance, including sun-stimulated fluorescence. These in situ observations will be compared with data from the next-generation ocean color sensor, MODIS, which will measure chlorophyll fluorescence efficiency. These measurements will focus on five basic questions: 1. What are the scales of variability of primary productivity and how are these related to physical processes? 2. How do the patterns of mesoscale variability and primary productivity vary north and south of Cape Blanco? 3. How does the relationship between mesoscale variability and productivity change seasonally during the upwelling season? 4. What is the relative importance of light and nutrient availability on phytoplankton productivity in the nearshore zone? and 5. How long are phytoplankton retained within a feature and what is the relative importance of in situ growth versus advection/convergence in determining phytoplankton standing stocks?