Collaborative Research: The Great Southern Coccolithophore Belt

智力优点：卫星遥感的最新进展使人们能够从空间估计悬浮碳酸钙（颗粒无机碳或“PIC”）。这种辐射方法是具体操作的海洋颗石藻（Haptophyceae）和敏感性足以量化PIC浓度在寡营养环流。在中分辨率成像分光仪Aqua使命的七年中拍摄的悬浮PIC的全球图像显示，在南大洋的亚南极前沿附近有一个环绕地球仪的PIC“大带”。这一特征每年发生在南半球夏季，似乎是在南大洋的高营养，低叶绿素区域。大带的面积约为8800万平方公里，占全球海洋的26%。对大西洋、印度洋和太平洋区域的大带区域进行的几次航行所得到的证据证实，颗石藻的浓度较高;以前在大西洋区域进行的工作证实，事先知情同意的光学散射很高。我们所拥有的少数船只观测结果与卫星图像完全一致。在该项目中，调查人员将以下列科学目标为指导，系统地研究大带的颗石藻：（a）确定该带内的颗石藻物种;（B）测量颗石藻和相关PIC的丰度;（c）测量颗石藻钙化率;（d）测量颗石藻的数量;（d）阐明可能限制颗石藻纬度范围的因素（e）证明事先知情同意的可变性是否与浅层输出通量有关;（f）确定事先知情同意程序生产的可变性与二氧化碳分压、总碱度和溶解无机碳收支之间的关系;（g）研究短期海洋酸化对颗石藻生长和方解石溶解的影响。这项研究将包括沿着南纬50度对大带进行采样，在南半球的夏天进行。调查人员将结合使用正在进行的表面采样（主要是光学和水文）和垂直站剖面（使用CTD/玫瑰花和大容量潜水泵），以解决与上述目标有关的假设。巡航轨迹将阐明大带的纬向和纬向变化。受控大玻璃瓶培养实验将研究海洋酸化在未来各种情景下对颗石藻生长和溶解的影响。稀释实验将解决放牧相关的死亡率和溶解问题。受控金属添加孵化将集中在潜在的铁，锌和钴的限制的颗石藻或竞争硅藻有关的二氧化硅的可用性。拟议的实地观测和金属添加实验将提供关于全球地球化学背景下大带现状的重要信息。即将进行的海洋酸化实验对于南大洋颗石藻在未来酸化海洋中的命运更具前瞻性。 更广泛的影响：大带的全球重要规模表明，它可能在全球地球化学和气候变化反馈中发挥重要作用。因此，研究人员预计这项工作将对生物和化学海洋学产生广泛的变革性影响。据预测，燃烧化石燃料造成的海洋酸化将在下一个世纪使海洋表面的pH值降低0.3个单位，到2300年将使质子浓度增加5倍。这项研究的一个主要目标是检查海洋酸化对低方解石饱和度区域（即，预期成为方解石亚饱和的第一个区域之一）。因此，这些实验的结果将与我们对海洋碳循环的基本理解高度相关。与职业发展和标准II活动有关，该项目包括为来自缅因州大学或学院的NSF REU本科生提供两次巡航的实地经验，为他们参加科学会议提供资金。来自缅因州大学的本科生的参与增强了我们沿海农村州的能力，并有助于阻止“人才外流”的严重问题，即最优秀的学生离开缅因州，到更富裕、人口更多的州寻求机会。一名教师也将参加游轮（通过NSF赞助的阿尔马达计划）。这名教师将为学生编写关于颗石藻、钙化、出口生产、金属-浮游生物相互作用、海洋酸化和气候变化等专题的学习模块。

Intellectual merit: Recent advances in satellite remote sensing enable estimation of suspended calcium carbonate (particulate inorganic carbon or 'PIC') from space. This radiative approach is operationally specific to marine coccolithophores (Haptophyceae) and sensitive enough to quantify PIC concentrations in oligotrophic gyres. Global images of suspended PIC taken over the seven years of the MODIS Aqua mission show a 'Great Belt' of PIC near the sub-Antarctic front of the Southern Ocean that circles the globe. This feature occurs every year during austral summer and appears to be within the high-nutrient, low chlorophyll region of the Southern Ocean. The area of the Great Belt is ~88 million km2, 26% of the global ocean. Evidence from several cruises into the Great Belt region of the Atlantic, Indian and Pacific sectors has verified elevated concentrations of coccolithophores; previous work in the Atlantic sector verified high optical scattering from PIC. The few ship observations we have are entirely consistent with the satellite views. In this project, the investigators will systematically study the coccolithophores of the Great Belt guided by the following science goals: (a) identify the coccolithophore species within this belt; (b) measure the abundance of coccolithophores and associated PIC; (c) measure coccolithopore calcification rates; (d) elucidate factors that may limit coccolithophore latitudinal range (e.g. stratification, temperature, macronutrients, trace metals, grazing); (e) demonstrate whether the variability in PIC relates to shallow export flux; (f) define how variability in PIC production relates to the pCO2, total alkalinity and dissolved inorganic carbon budgets; and (g) examine the impact of short-term ocean acidification on coccolithophore growth and calcite dissolution. The research will involve cruises along the 50 S parallel to sample the Great Belt, during the austral summer. The investigators will use a combination of underway surface sampling (primarily optical and hydrographic) and vertical station profiles (using CTD/rosette and large volume submersible pumps) to address hypotheses related to the above goals. The cruise track will elucidate both zonal and meridional variability in the Great Belt. Controlled carboy incubation experiments will examine the impact of ocean acidification at various future scenarios on coccolithophore growth and dissolution. Dilution experiments will address grazing-related mortality and dissolution questions. Controlled metal-addition incubations will focus on potential iron, zinc and cobalt limitation of the coccolithophores or competition from diatoms related to silica availability. The proposed field observations and metal-addition experiments will provide important information on the current status of the Great Belt in the context of global biogeochemistry. The ocean acidification experiments to be undertaken are more forward-looking in terms of the fate of the Southern Ocean coccolithophores in a future acidified ocean. Broader impacts: The globally significant size of the Great Belt indicates that it likely plays a major role in global biogeochemistry and climate change feedbacks. Thus, the investigators expect this work to have broad, transformative impacts in biological and chemical oceanography. Ocean acidification from the burning of fossil fuels is predicted to lower the pH of the surface ocean by 0.3 units in the next century and up to 0.7 units - a 5-fold increase in the proton concentration by the year 2300. A major goal of this study is to examine the effects of ocean acidification on coccolithophores in a region of low calcite saturation (i.e., one of the first regions expected to become sub-saturating for calcite). The results of these experiments will therefore be highly relevant to our basic understanding of the marine carbon cycle. Related to career development and Criterion II activities, the project includes field experience on two cruises for NSF REU undergraduates from Maine universities or colleges, providing funds for them to attend a scientific meeting. Participation of undergraduate students from Maine colleges builds capacity in our rural coastal state and helps thwart the serious issue of 'brain drain', in which the best students are leaving Maine to seek opportunity in wealthier, more populated states. A teacher will also participate on the cruises (via the NSF-sponsored ARMADA program). This teacher will develop learning modules for students about such topics as coccolithophores, calcification, export production, metal-plankton interactions, ocean acidification and climate change.