Arctic Prize: Absorption of light by Arctic marine phytoplankton, its ecological and biogeochemical significance

该项目福尔斯海洋环境研究领域，与气候变化研究领域有关。该项目由NERC资助，与斯特拉斯克莱德大学、格拉斯哥大学、SAMS和挪威合作伙伴合作。北冰洋正在经历明显的变化，以应对气候强迫，增加淡水输入（Morison等人，2012年），水温升高和多年海冰范围减少（例如，Overland等人，2014）。已经观察到浮游植物水华物候学从单水华极地模式转变为温带模式双水华物候学，并且在外围北极海中贫营养增加（例如Ardyna等人，2014; Li等人，2009年）的报告。因此，希望了解这对整个初级生产和碳出口的任何变化的影响。北极碳输出的增加可能对气候变化产生负面反馈，而输出受损可能加剧大气中二氧化碳的积累。为了探讨这一问题，必须调查北极海洋浮游植物不同功能群的生理特性和吸收系数，以便通过卫星检索廉价地量化它们的存在和对初级生产的贡献。研究开始于我博士学位开始时的4次巴伦支海巡航（2次在夏季，1次在极地夜晚，1次在春季），目的是了解巴伦支海浮游植物的垂直群落结构和季节生理变化。将重点放在冰包的边缘，以调查冰下浮游植物水华的新报告（Arrigo等人，2012年）。第一次巡航已经完成（2017年7月）。石楠·布曼博士在船上用放射性标记的浮游植物培养物进行了光生理学实验，在巴伦支海的一些站从不同深度收集了海水样品，并进行了过滤，以收集浮游植物。浓缩的浮游植物样本随后被快速冷冻，等待随后的分析。将采用高效液相色谱色素分析、浮游植物光吸收、光学显微镜和细胞计数来确定不同浮游植物群体的色素补充、细胞大小和光适应对其吸收不同频率光的效率的重要性。还将利用所收集样品的培养和船上反射数据来调查浮游植物生理学，并协助卫星检索的遥感校准。该项目将在石楠布曼博士和大卫麦基博士的联合监督下进行，航行后的后续研究将侧重于改进遥感算法和与模拟初级生产的科学家进行交流。鉴于不同种类的浮游植物以不同的速率和每单位日照的效率固定碳，北极浮游植物群落的物候学研究具有重大的科学和经济意义，例如，确定在气候变化情景下北极的碳固定率将如何进行，并确定群落组成和初级生产变化对亚北极捕鱼的重要性以及北极圈外围海域。

This project falls with the Marine environments research area and is relevant to the climate change research area. The project is NERC funded, collaborating with the University of Strathclyde, Glasgow, SAMS and Norwegian partners. The Arctic ocean is undergoing pronounced change in response to climate forcing, with enhanced fresh water input (Morison et al., 2012), increased water temperature and decreased multi-year sea ice extent (e.g. Overland et al., 2014). There has been an observed shift in phytoplankton bloom phenology from a single-bloom polar-mode to a temperate-mode double bloom phenology and increased oligotrophy in peripheral arctic seas (e.g. Ardyna et al., 2014; Li et al., 2009). It is therefore desirable to know about the implications this has for any change to overall primary production and carbon export. Increased Arctic carbon export could act as a negative feedback on climate change, while an impaired export could exacerbate atmospheric carbon dioxide accumulation. In order to probe this question the physiological properties and absorption coefficients of different functional groups of Arctic marine phytoplankton must be investigated, so that their presence and contribution to primary production can be quantified inexpensively by satellite retrievals. The research begins with 4 cruises to the Barents sea (2 in summer, 1 in polar night, 1 in spring) at the start of my PhD, with a view to characterise the vertical community structure of phytoplankton of the Barents sea and variations in physiology through the seasons. There will be a focus on the edge of the icepack to investigate novel reports of under-ice phytoplankton blooms (Arrigo et al., 2012). The first cruise has already been completed (July 2017). Photophysiological experiments were conducted using radio-labelled phytoplankton incubations aboard the ship, by Dr. Heather Bouman.Sea water samples were collected from various depths at a number of stations in the Barents sea and were filtered in order to collect the phytoplankton. The concentrated phytoplankton samples were subsequently flash-frozen and are awaiting subsequent analysis. High-Performance Liquid Chromatography pigment analysis, phytoplankton light absorption, optical microscopy and cell-counting will be employed to determine the importance of the pigment complement, cell size and photoacclimation of different phytoplankton groups to their efficiency absorbing different frequencies of light. Incubations of collected samples and shipboard reflectance data will also be employed to investigate phytoplankton physiology and to assist in remote sensing calibration of satellite retrievals. The project will be undertaken under the joint supervision of Dr. Heather Bouman and Dr. David Mckee and subsequent research following the cruises will focus on refinement of remote sensing algorithms and communication with scientists modelling primary production. Given that different groups of phytoplankton fix carbon with different rates and efficiencies per unit insolation, the study of the phenology of Arctic phytoplankton communities has applications of great scientific and economic importance, for example to determine how rates of carbon fixation in the Arctic will proceed under climate change scenarios and to determine the significance of community composition and primary production changes on fishing in the subarctic and peripheral arctic seas.