Phytoplankton Populations in the Equatorial Pacific: Distributions and Growth Rates from Individual Cell Properties

美国赤道太平洋全球海洋通量联合研究的核心任务是了解浮游食物网的组成，以及将碳输送到深海的效率。提出的一个具体问题是，铁的可获得性是否限制了这一地区的生产率。该项目将通过对食物网中的浮游植物成分进行流式细胞仪分析，解决整个赤道太平洋计划的若干方面问题。具体来说，该项目将：(1)在横跨赤道的样带上测量微浮游植物和较大浮游植物的分布、丰度和光散射特性；(2)测量单个细胞的细胞数量、前向光散射(大小)和DNA含量的每日变化，这些变化可转化为净种群增长率和总种群增长率的估计；(3)使用所测量的单胞数量和每个单胞的光散射的日变化来帮助解释光束衰减测量；(4)测试铁限制赤道太平洋浮游植物生长的假设，方法是测量每个细胞的前向光散射、每个细胞的碳-14掺入量以及浮游植物特定成分的DNA在每个细胞上的分布，以响应铁的增加。//

Central to the mission of the US Joint Global Ocean Flux Study in the equatorial Pacific is an understanding of the composition of the planktonic food web, and the efficiency with which it transports carbon to the deep ocean. One of the specific questions being posed is whether or not iron availability is limiting productivity in this area. This project will address several dimensions of the overall equatorial Pacific plan through the flow cytometric analysis of the phytoplankton component of the food web. Specifically, the project will: (1) Measure the distribution, abundance, and light scatter properties of the picoplankton, and of the larger phytoplankton, on a transect across the equator; (2) Measure the daily changes in cell number, forward light scatter (size), and DNA content of individual cells, which can be translated into estimates of net and gross population growth rates; (3) Use the measured daily changes in cell number and light scatter per cell to help interpret beam attenuation measurements; (4) Test the hypothesis that iron limits phytoplankton growth in the equatorial Pacific by measuring changes in forward light scatter per cell, carbon-14 incorporation per cell, and the distribution of DNA per cell of specific components of the phytoplankton, in response to iron enrichment. //