Collaborative Research: Interactive Effects of Iron, Light and CO2 on Phytoplankton Community Dynamics in the Ross Sea

这项建议的目的是调查对南大洋两个主要的水华浮游植物种类--硅藻和南极洲棕囊藻--的大规模分布和生产的控制。这两个类群通过参与碳、硫和营养元素的生物地球化学循环，可能在晚第四纪的气候变化中发挥了重要作用，也可能在未来的环境变化中发挥关键作用。目前的一个范例是，辐射和铁的可获得性推动了南大洋浮游植物的动态。然而，最近的研究表明，由于不同物种在生理上的差异，二氧化碳(CO2)浓度在构建藻类组合时也可能是重要的。这项建议研究了铁、光和二氧化碳对南大洋棕囊藻和硅藻的生理、生态和相对优势的交互影响。罗斯海是研究调节这两类藻类分布和繁殖的环境因素的理想系统，因为它的特点是南极洲南极洲和硅藻的季节性繁殖，而硅藻通常在空间和时间上是分开的。这项研究将采取跨学科调查的形式，包括对罗斯海南部的藻类组合组成、铁、混合层深度和二氧化碳水平进行实地调查和统计分析，并进行船上实验，以考察硅藻和南极洲藻类对春季和夏季铁、光和二氧化碳高低水平的响应。该项目将提供关于控制南大洋两大水华浮游植物的生产和分布的一些主要因素以及有关碳、硫和营养元素的生物地球化学循环的资料。这些结果最终可能会提高预测南大洋将如何受到未来气候变化的影响，并可能对其进行调节的能力。该项目还将在几个层面上对教育作出重大贡献，包括计划让研究生和本科生、博士后助理、一名实习教师以及社区外联和教育活动参与研究。计划开展一些活动，使该项目与K-12教育相衔接。将在当地学校发表演讲，讨论研究巡航的研究和活动。在邮轮期间，将每天与小学教室进行互动电子邮件联系。建立的网站将让学生了解正在进行的研究，并允许研究人员通过文本和下载的图像与学生交流。

The objectives of this proposal are to investigate the controls on the large-scale distribution and production of the two major bloom-forming phytoplankton taxa in the Southern Ocean, diatoms and Phaeocystis Antarctica. These two groups, through their involvement in the biogeochemical cycles of carbon, sulfur and nutrient elements, may have played important roles in the climate variations of the late Quaternary, and they also may be key players in future environmental change. A current paradigm is that irradiance and iron availability drive phytoplankton dynamics in the Southern Ocean. Recent work, however, suggests that carbon dioxide (CO2) concentrations may also be important in structuring algal assemblages, due to species-specific differences in the physiology. This proposal examines the interactive effects of iron, light and CO2 on the physiology, ecology and relative dominance of Phaeocystis and diatoms in the Southern Ocean. The Ross Sea is an ideal system in which to investigate the environmental factors that regulate the distribution and production of these two algal groups, since it is characterized by seasonal blooms of both P. Antarctica and diatoms that are typically separated in both space and time. This study will take the form of an interdisciplinary investigation that includes a field survey and statistical analysis of algal assemblage composition, iron, mixed layer depth, and CO2 levels in the southern Ross Sea, coupled with shipboard experiments to examine the response of diatom and P. Antarctica assemblages to high and low levels of iron, light and CO2 during spring and summer. This project will provide information on some of the major factors controlling the production and distribution of the two major bloom forming phytoplankton in the Southern Ocean and the related biogeochemical cycling of carbon, sulfur and nutrient elements. The results may ultimately advance the ability to predict how the Southern Ocean will be affected by and possibly modulate future climate change. This project will also make significant educational contributions at several levels, including the planned research involvement of graduate and undergraduate students, postdoctoral associates, a student teacher, and community outreach and educational activities. A number of activities are planned to interface the project with K-12 education. Presentations will be made at local schools to discuss the research and events of the research cruise. During the cruise there will be daily interactive email contact with elementary classrooms. Established websites will be used to allow students to learn about the ongoing research, and to allow researchers to communicate with students through text and downloaded images.