The Role of Protozoan Zooplankton in Plankton Community Structure, Composition and Fate in the Equatorial Pacific

该项目是美国中赤道太平洋全球海洋通量联合研究(JGOFS)的组成部分。在这一区域进行了一些观察，这与我们对营养状况和浮游生物群落结构与垂直通量之间关系的一些传统概念相矛盾。高氮浓度和高供给率通常与富营养条件有关，但与相对较低的叶绿素、初级生产力和“新产量”共存--这是低营养水域的特征。较小的微微和纳米浮游植物细胞主导浮游植物(查韦斯等人)。在新闻报道中)，但生物沉淀率很高，并与初级生产相关。高通量通常被认为与大型细胞有关，如硅藻，从表面水域下沉，或被较大的细胞吞噬，产生粪便颗粒的后生浮游动物。这些明显的矛盾表明，浮游植物的大小结构、原生动物与后生动物放牧的后果，以及它们与表层物质垂直通量的关系还没有完全了解。该项目将通过测量地表水中光生微微浮游生物、光养和异养纳米浮游生物、食性原生动物的丰度和生物量，以及原生浮游动物的放牧影响和生长率来研究这些矛盾。我们的研究将使用经过验证的、最先进的彩色图像分析和荧光显微镜相结合的方法来描述浮游生物的大小、营养和分类结构。结果将用于确定原生动物浮游动物在中赤道太平洋表层水域颗粒有机物的生产、消费和输出的耦合中所起的作用。

This project constitutes a portion of U.S. joint global ocean flux study (JGOFS) of the central equatorial Pacific. Several observations have been made in this region which contradict some of our conventional concepts of trophic status and the relationship between plankton community structure and vertical flux. High nitrogen concentrations and supply rates, usually associated with eutrophic conditions, co-exist with relatively low chlorophyll, primary productivity, and "new production" - which are characteristics of oligotrophic waters. Smaller pico- and nanoplankton cells dominate the phytoplankton (Chavez, et.al. in press), yet significant rates of biogenic sedimentation occur and is correlated with primary production. High flux rates are usually thought to be associated with large cells, such as diatoms, sinking out of surface waters or being consumed by larger cells, fecal pellet-producing metazooplankton. These apparent contradictions indicate that the consequences of phytoplankton size structure, protozoan versus metazoan grazing, and their relationship to vertical flux of material out of the surface layer are not fully understood. This project will examine these contradictions by measuring the abundances and biomass of the phototropic picoplankton, phototrophic and heterotrophic nanoplankton, and phagotrophic protozoans in the surface water, and the grazing impact and growth rates of protozooplankton. We study will employ proven, state-of-the-art color image analysis combined with epifluorescence microscopy to describe the size, trophic and taxonomic structure of the plankton. Results will be used to determine the role of protozoan zooplankton in the coupling of production, consumption and export of particulate of particulate organic matter in the surface waters of the central equatorial Pacific.