Patagonian Shelf Coccolithophores: Ecological Factors Regulating the Southern Hemisphere's Largest Recurring Coccolithophore Bloom

巴塔哥尼亚大陆架颗石藻：调节南半球最大的周期性颗石藻水华的生态因素

• 批准号: 0728582
• 负责人: William Balch
• 金额: $ 49.57万
• 依托单位: Bigelow Laboratory for Ocean Sciences
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-15 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0728582&HistoricalAwards=false
• 关键词: Patagonian; Shelf; Coccolithophores; Ecological; Factors

This project will study coccolithophores at the fringes of the Southern Ocean on the Patagonian Shelf (PS) east of Argentina. Some of the most extensive coccolithophore blooms in the world occur on the PS but the remoteness of the region has impeded their study. In this part of the southern ocean, the most basic knowledge is lacking about a) the relationships between coccolithophores and other species of phytoplankton, b) the impact of coccolithophores on the carbon cycle and c) how environmental changes affect bloom taxonomy and function. This will be the first multi-disciplinary ship-based investigation of these mesoscale blooms, building on an understanding of coccolithophore ecology derived almost exclusively from northern hemisphere bloom studies. This study will document the factors regulating the spatial-temporal distribution of the coccolithophore blooms, using a combination of underway, satellite and discrete sampling. Satellite measurements will provide quantitative estimates of particulate inorganic carbon (PIC) and particulate organic carbon (POC) in coccolithophore blooms while underway hydrographic and optical sampling will allow real-time evaluation of coccolithophores in both bloom and surrounding non-bloom waters. Vertical casts across the shelf front will provide depth resolved coccolithophore abundance as well as estimates of phytoplankton species richness. Another goal is to examine the effects of ocean acidification on algal optical properties, coccolithophore concentrations and PIC concentrations (to be determined from deck experiments). Dilution experiments will provide key estimates on phytoplankton growth rates, coccolithophore growth rates and calcification rates, plus the intrinsic loss rates (i.e. phytoplankton grazing, coccolithophore grazing and dissolution associated with zooplankton grazing). PIC has not been examined in dilution experiments heretofore. The project will yield fundamental insights into a) our understanding of coccolithophore ecology (not just Emiliania huxleyi) and b) the utility of the "functional group" concept to describe coccolithophore variability over the PS. Such knowledge is critical to model complex biogeochemical processes that regulate phytoplankton production and the biological pump. It is also worthy of note that the PS coccolithophore populations are at the western edge of a southern hemisphere belt of enhanced coccolithophores thought to extend from the southern tip of South America to waters south of Australia, (~180o of longitude). This study will provide the first detailed analysis of the coccolithophores in this enormous area of high suspended calcite water.Broader impacts : The burning of fossil fuels is predicted to increase atmospheric CO2 to 750 p.p.m.v. or more under various future scenarios. As a large fraction of the anthropogenic CO2 diffuses into seawater, the ocean is becoming more acidic; it is predicted that the pH of the surface ocean will drop by up to 0.7 units by year 2300, a 5-fold increase in the proton concentration. A major goal is to examine the effects of ocean acidification on coccolithophores, in a region of low calcite saturation. The results will be highly relevant to our basic understanding of the marine carbon cycle. This project includes funds for an REU student from a Maine university or college to work at Bigelow Laboratory and to attend a national scientific meeting each year. Participation of undergraduate students from Maine colleges builds capacity in this rural coastal state, helping to thwart the issue of "brain-drain", in which the best students leave Maine to seek opportunity in more populated states. The project includes a teacher training component to develop learning modules for teachers about such areas as coccolithophores, calcification and climate change.

该项目将研究阿根廷以东巴塔哥尼亚陆架(PS)南大洋边缘的球石生物。世界上一些最广泛的孢子虫水华发生在PS上，但该地区的偏远阻碍了他们的研究。在南大洋的这一部分，最基本的知识缺乏：a)球藻与其他浮游植物物种之间的关系；b)球藻对碳循环的影响；c)环境变化如何影响水华的分类和功能。这将是对这些中尺度水华的第一次多学科船基调查，建立在几乎完全来自北半球水华研究的对球虫生态的理解基础上。这项研究将使用在航、卫星和离散采样相结合的方法，记录调控球藻水华时空分布的因素。卫星测量将提供球藻水华中颗粒无机碳(PIC)和颗粒有机碳(POC)的定量估计，而正在进行的水文和光学采样将能够实时评估水华和周围非水华水域中的球藻生物。横跨陆架前缘的垂直投射将提供深度分辨的球藻生物体丰度以及浮游植物物种丰富度的估计。另一个目标是研究海洋酸化对藻类光学性质、球藻基团浓度和PIC浓度的影响(将通过甲板实验确定)。稀释实验将提供对浮游植物生长率、球藻生长率和钙化率以及固有损失率(即浮游植物放牧、球藻放牧和与浮游动物放牧相关的溶解)的关键估计。到目前为止，还没有在稀释实验中检测到PIC。该项目将对a)我们对球石生物体生态的理解(不仅仅是Emily huxleyi)和b)“官能团”概念在PS上描述球石生物体的可变性产生基本的见解。这些知识对于建立调控浮游植物生产和生物泵的复杂生物地球化学过程的模型至关重要。还值得注意的是，PS球石生物群位于南半球强化球石生物带的西侧边缘，被认为是从南美洲南端延伸到澳大利亚以南的水域(经度约180度)。这项研究将首次对这片巨大的高悬浮方解石水域中的球石生物进行详细分析。负面影响：化石燃料的燃烧预计将使大气中的二氧化碳增加到每分钟750二氧化碳。或者在未来的各种情况下会更多。随着很大一部分人为二氧化碳扩散到海水中，海洋正变得更加酸性；据预测，到2300年，表层海洋的pH值将下降多达0.7个单位，质子浓度将增加5倍。一个主要目标是在方解石饱和度较低的地区检查海洋酸化对球石生物体的影响。这一结果将与我们对海洋碳循环的基本理解高度相关。该项目包括每年资助缅因州大学或学院的一名REU学生在毕格罗实验室工作和参加一次全国科学会议。来自缅因州大学的本科生的参与在这个沿海农村州建立了能力，帮助阻止了人才外流的问题，即最优秀的学生离开缅因州到人口更稠密的州寻找机会。该项目包括一个教师培训部分，为教师编制有关球虫生物、钙化和气候变化等领域的学习模块。