Microzooplankton Grazing Interactions in the Central Equatorial Pacific

赤道中太平洋是一个广泛的高营养物质上升流、初级生产力增强和浮游生物密度增加的地区，这对联合全球海洋通量研究(JGOFS)特别感兴趣，因为它可能占全球向深海输出碳的估计速率的20%至50%。这项研究的总体目标是作为JGOFS赤道太平洋方案的一个组成部分，帮助理解该区域初级生产、食物网络结构和生物地球化学循环与通量之间的关系。这项研究利用一套互补的实验方法(荧光标记的猎物颗粒、代谢抑制剂和海水稀释)和流式细胞仪技术来确定主要的微消费者群体，并在不同的时间和空间尺度上测量他们的放牧率、行为和社区影响。具体地说，这项研究将1)确定跨赤道断面上微微型和微型浮游生物群落的分布、丰度和生物量及其随深度和纬度的变化；2)识别和量化微型浮游动物对微型和微型浮游生物群落的优势捕食者；3)确定微型浮游动物对细菌、原生绿藻、蓝藻、和藻类作为深度、一天中的时间和营养状态的函数，4)评估存在一般大小关系的假设，该假设将放牧对微浮游动物种群的影响的比率联系起来，并测试这样的假设，即浮游鞭毛虫之间的混合营养作用将沿着从富营养化(富营养化)到贫营养化(营养贫乏)系统的环境梯度以及在真光带的低光照条件下增加。

The central equatorial Pacific is an extensive region of high nutrient upwelling, enhanced primary productivity, and elevated plankton concentrations that is of special interest to the Joint Global Ocean Flux Studies (JGOFS) because it may account for 20 to 50% of the estimated global rate of carbon export to the deep sea. The general goal of this research is to contribute to understanding the relationships among primary production, food- web structure, and biogeochemical cycling and fluxes in this region as a component of the JGOFS Equatorial Pacific Program. The research utilizes a complementary set of experimental approaches (fluorescently-labelled prey particles, metabolic inhibitors, and seawater dilution) and flow cytometry techniques to identify major microconsumer groups and to measure their grazing rates, behaviors, and community impacts at different temporal and spatial scales. Specifically, the research will 1) determine the distributions, abundances, and biomass of pico- and nanoplankton communities and their variations with depth and latitude on cross-equatorial transects, 2) identify and quantify the dominant microzooplankton grazers on pico- and nanoplankton communities, 3) determine the grazing impact of microzooplankton on component populations of bacteria, prochlorophytes, cyanobacteria, and algae as functions of depth, time of day, and trophic state, 4) evaluate the hypothesis that there is a general size relationship linking the rates of grazing impact on picoplankton populations, and test the hypotheses that the role of mixotrophy among planktonic flagellates will increase along environmental gradients from eutrophic (nutrient-rich) to oligotrophic (nutrient-poor) systems and at low light levels in the euphotic zone.