The Impact of Protozoan Zooplankton on the Structure, Composition and Fate of the North Atlantic Spring Bloom

最近的实地研究有力地表明，纳米和微微浮游生物是公海的主要初级生产者。它们对粮食供应变化的快速反应时间被认为在真光区的生产和消费之间保持着实质性的耦合。然而，沉积物捕捉器的收集表明，从上层混合层到海底的大量垂直颗粒通量与浮游植物水华有关。水华本身被认为是大型浮游动物和体型较大的浮游植物之间脱钩的证据。这些相互矛盾的假设强调了这样一个事实，即公海小型和大型浮游植物的相对重要性、原生动物和后生动物食草动物在调节其动态方面的作用、这些过程的时间和空间异质性以及它们与混合层颗粒输出的关系尚不为人所知。这些想法已经凝聚成一项关于东北大西洋春季水华的起源和命运的国际研究(JGOFS)。这部分研究将量化自养微微浮游生物、自养和异养纳米浮游生物以及食性原生动物的丰度、生物量、分类和营养成分，并测量原生浮游动物的放牧影响和生长率。这些研究将使用尖端技术进行，包括自动彩色图像分析、荧光和电子显微镜以及高效液相色谱法。研究结果将被用来分析浮游原生动物在维持上层海洋颗粒状有机物的生产、消费和输出之间的耦合中所起的作用。

Recent field studies strongly implicate nano- and picoplankton as the dominant primary producers in the open ocean. Their rapid response times to changes in food supply are thought to maintain substantial coupling between production and consumption in the euphotic zone. Yet sediment trap collections indicate that significant episodes of vertical particle flux from the upper mixed layer to the seafloor are associated with phytoplankton blooms. The blooms themselves are offered as evidence of decoupling, presumably between macrozooplankton and larger size classes of phytoplankton. These conflicting hypotheses underscore the fact that the relative importance of small and large phytoplankton in the open sea, the role of protozoan and metazoan grazers in regulating their dynamics, the temporal and spatial heterogeneity of these processes, and their relationship to particle export out of the mixed layer are not well known. These ideas have coalesced into an international study (JGOFS) of the origin and fate of the spring bloom in the Northeast Atlantic Ocean. This portion of the study will quantify the abundance, biomass, taxonomic, and trophic composition of autotrophic picoplankton, autotrophic and heterotrophic nanoplankton, and phagotrophic protozoans, and measure the grazing impact and growth rates of protozooplankton. These studies will be conducted using sophisticated technology, including automated color image analysis, epifluorescence and electron microscopy, and HPLC. The results will be used to analyze the role of protozoan zooplankton in preserving coupling between the production, consumption, and export of particulate organic matter in the upper ocean.