Microzooplankton Grazing Interactions in the Central Equatorial Pacific

赤道中太平洋是一个具有高营养上升流、初级生产力增强和浮游生物浓度升高的广阔区域，这是全球海洋通量联合研究（JGOFS）特别感兴趣的区域，因为它可能占估计的全球向深海输出的碳量的20%至50%。本研究的总体目标是作为JGOFS赤道太平洋项目的一个组成部分，有助于了解该地区初级生产、食物网结构、生物地球化学循环和通量之间的关系。本研究利用一套互补的实验方法（荧光标记猎物颗粒、代谢抑制剂和海水稀释）和流式细胞术技术来确定主要的微消费者群体，并测量他们在不同时空尺度上的放牧率、行为和群落影响。具体而言，本研究将：(1)确定跨赤道样带上微型和纳米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)确定并量化微型浮游动物对微型和纳米浮游生物群落的优势食草动物；(3)确定微型浮游动物对细菌组成种群的放牧影响；原绿藻、蓝藻和藻类作为深度、时间和营养状态的函数，4)评估了放牧对浮游生物种群影响的速率之间存在一般大小关系的假设；并验证浮游鞭毛虫的混合营养作用将在富营养化（富营养化）到贫营养化（贫营养化）系统的环境梯度中以及在光强区低光照水平下增加的假设。

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.