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

该项目将研究阿根廷东部巴塔哥尼亚大陆架（PS）南大洋边缘的颗石藻。世界上一些最广泛的球石藻华发生在PS上，但该地区的偏远程度阻碍了它们的研究。在南大洋的这一部分，缺乏最基本的知识：a)颗石藻与其他种类的浮游植物之间的关系，b)颗石藻对碳循环的影响，c)环境变化如何影响水华分类和功能。这将是对这些中尺度水华的首次多学科船舶调查，建立在几乎完全来自北半球水华研究的对球石藻生态学的理解的基础上。本研究将采用人工、卫星和离散采样相结合的方法，记录调节球石藻华时空分布的因素。卫星测量将提供球石藻华中颗粒无机碳（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允许实时评估开花和周围非开花水域的球石藻。跨越大陆架前沿的垂直投模将提供深度解析的球石藻丰度以及浮游植物物种丰富度的估计。另一个目标是检查海洋酸化对藻类光学特性、球石藻浓度和PIC浓度（由甲板实验确定）的影响。稀释实验将提供浮游植物生长速率、球石藻生长速率和钙化速率的关键估计，以及固有损失率（即浮游植物放牧、球石藻放牧和与浮游动物放牧相关的溶解）。迄今为止，PIC尚未在稀释实验中得到检验。该项目将对以下方面产生根本性的见解：a)我们对颗石藻生态学的理解（不仅仅是埃米利亚·赫胥黎）；b)利用“官能团”概念来描述PS上的颗石藻变变性。这些知识对于模拟调节浮游植物生产和生物泵的复杂生物地球化学过程至关重要。同样值得注意的是，PS球石群群位于南半球增强球石群带的西部边缘，该带被认为从南美洲南端延伸到澳大利亚以南水域（经度~180度）。这项研究将首次对这片巨大的高悬浮方解石水域的球石藻进行详细的分析。更广泛的影响：化石燃料的燃烧预计将使大气中的二氧化碳在未来各种情况下增加到每加仑750或更多。随着大部分人为排放的二氧化碳扩散到海水中，海洋变得越来越酸；据预测，到2300年，海洋表面的pH值将下降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藻的影响。这些结果将与我们对海洋碳循环的基本认识高度相关。该项目包括资助一名来自缅因州大学或学院的REU学生在毕格罗实验室工作，并每年参加一次国家科学会议。缅因州大学本科生的参与为这个沿海乡村州建立了能力，有助于阻止“人才流失”问题，即最优秀的学生离开缅因州到人口更密集的州寻找机会。该项目包括教师培训部分，为教师开发有关粒石藻、钙化和气候变化等领域的学习模块。

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.