Biogenic silica production and diatom dynamics in the Svalbard region during spring 2016

Raw data used in the publication of \"Biogenic silica production and diatom dynamics in the Svalbard region during spring 2016\". ARCEx. The Research Centre for Arctic Petroleum Exploration, ARCEx, is a research collaboration between academia and industry with support from the Research Council and Norwegian authorities. Through a common effort, the project contributes to the understanding of the geology and resource potential of the high north, the development of new geophysical exploration techniques suitable for the Arctic and new models for environmental risk connected to operations in the north. Education and training is an integrated part of ARCEx. ARCEx is hosted by UiT The Arctic University of Norway in Tromsø. Cruise goal and duration. The overarching goal of the ARCEx cruise was to study the pelagic and benthic ecosystem during Arctic spring bloom scenarios in fjords at western Svalbard (van Mijenfjorden and Hornsund), a coastal scenario (Storfjorden) and the western Barents Sea (in the Arctic influenced Erik Eriksen Strait, the Polar Front and at an Atlantic influenced location). This study was conducted onboard the FF Helmer Hanssen between 17 and 29 May 2016 with Dr. Ingrid Wiedmann serving as Chief Scientist. Data collection. All samples reported in this data set were collected either using a water-column CTD Rosette sampler with Niskin bottles or short-duration sediment traps. The CTD package was a Seabird Electronics (SBE) 911plus with a photosynthetically active radiation sensor (Biospherical/Licor, SN 1060). Discreet samples were collected at targeted depths using 5-L Niskin samplers secured to the CTD Rosette system. Once on deck, water was sampled directly from the Niskin samplers to be processed for the measurements and methods described. The vertical flux of particulates was assessed by filtering water from the short-term (<1 day) deployed sediment traps (KC Denmark). Sediment trap cylinders (~72mm internal diameter, ~450mm length, ~1:8 L volume) were deployed at three to seven depths ranging between 20 and 150–200 m, based on bathymetry. At the two fjord stations (van Mijenfjorden, Hornsund), the sediment trap array was anchored to the bottom. In the more open regions of the drift ice covered Arctic station (Erik Eriksen Strait) and the open water stations in the Atlantic waters in the wester Barents Sea, the sediment trap array was anchored to an ice-floe and freely drifting, respectively. After recovery of the sediment traps, all cylinder contents at a particular depth were pooled in a acid-cleaned container, homogenized and subsampled for the measurements and methods described.
Abstract. Diatoms are generally the dominant contributors to the Arctic Ocean spring bloom, which is a key event in regional food webs in terms of capacity for secondary production and organic matter export. Dissolved silicic acid is an obligate nutrient for diatoms and has been declining in the European Arctic since the early 1990s. The lack of regional silicon cycling information precludes understanding the consequences of such changes for diatom productivity during the Arctic spring bloom. This study communicates the results from a cruise in the European Arctic around Svalbard, which reports the first concurrent data on biogenic silica production and export, export of diatom cells, the degree of kinetic limitation by ambient silicic acid, and diatom contribution to primary production. Regional biogenic silica production rates were significantly lower than those achievable in the Southern Ocean and silicic acid concentration limited the biogenic silica production rate in 95% of samples. Compared to diatoms in the Atlantic subtropical gyre, regional diatoms are less adapted for silicic acid uptake at low concentration, and at some stations during the present study, silicon kinetic limitation may have been intense enough to limit diatom growth. Thus, silicic acid can play a critical role in diatom spring bloom dynamics. The diatom contribution to primary production was variable, ranging from < 10% to ∼ 100% depending on the bloom stage and phytoplankton composition. While there was agreement with previous studies regarding the export rate of diatom cells, we observed significantly elevated biogenic silica export. Such a discrepancy can be resolved if a higher fraction of the diatom material exported during our study was modified by zooplankton grazers. This study provides the most direct evidence to date suggesting the important coupling of the silicon and carbon cycles during the spring bloom in the European Arctic.

本数据集为论文《2016年春季斯瓦尔巴德地区生源硅生产与硅藻动态》的配套原始数据。ARCEx（北极石油勘探研究中心，Research Centre for Arctic Petroleum Exploration）是由学术界与工业界合作开展的研究项目，得到了挪威研究理事会与挪威官方机构的资助。
该项目通过协同攻关，助力加深对北极高纬度区域地质与资源潜力的认知，研发适用于北极地区的新型地球物理勘探技术，以及构建针对北极作业相关环境风险的新型评估模型。教育与培训是ARCEx项目的核心组成部分，该项目由特罗姆瑟的挪威北极大学（UiT The Arctic University of Norway）托管。
航次目标与时长。本ARCEx航次的总体目标为，研究斯瓦尔巴德西部峡湾（范米恩峡湾与霍恩松德）、近岸海域（斯托尔峡湾）以及巴伦支海西部（受北极影响的埃里克埃里克森海峡、极锋区域，以及受大西洋影响的站位）的北极春季藻华场景下的浮游与底栖生态系统。本研究于2016年5月17日至29日期间在"FF Helmer Hanssen"号科考船上开展，由英格丽·韦德曼博士担任首席科学家。
数据采集。本数据集收录的全部样本，均采用带尼斯金采水瓶（Niskin bottles）的水柱式温盐深仪（CTD）采水架或短期沉积物捕集器（sediment traps）获取。CTD集成系统为海鸟电子公司（Seabird Electronics）SBE 911plus型，搭载光合有效辐射传感器（Biospherical/Licor, SN 1060）。研究人员通过固定于CTD采水架的5升尼斯金采样器，在预设深度采集离散水样。抵达甲板后，直接从尼斯金采样器中取水，用于后续按既定方法开展的测试分析。通过回收短期（<1天）部署的沉积物捕集器（KC Denmark），对颗粒物的垂直通量进行评估。沉积物捕集器圆筒（内径约72mm, 长度约450mm, 容积约1:8 L）根据水深地形，在20米至150–200米的范围内设置3至7个采集深度。在两个峡湾站位（范米恩峡湾、霍恩松德），沉积物捕集器阵列固定于海底。在漂流浮冰覆盖的北极站位（埃里克埃里克森海峡）以及巴伦支海西部大西洋水域的开阔水域站位，沉积物捕集器阵列分别固定于浮冰之上与自由漂流装置。沉积物捕集器回收后，将同一深度采集的全部圆筒内样品汇集至经酸清洗的容器中，均质化处理后分取子样本，用于后续按既定方法开展的测试分析。
摘要。硅藻通常是北冰洋春季藻华的优势类群，作为区域食物网的关键事件，其对于次级生产能力与有机质输出具有重要意义。溶解态硅酸是硅藻生长的必需营养盐，自20世纪90年代初以来，欧洲北极海域的硅酸浓度持续下降。当前区域硅循环相关数据的缺失，阻碍了学界对北极春季藻华期间硅藻生产力受此类变化影响的认知。本研究基于欧洲北极斯瓦尔巴德周边海域的科考航次成果，首次同步报道了生源硅生产与输出、硅藻细胞输出、环境硅酸对生源硅生产的动力学限制程度，以及硅藻对初级生产的贡献占比等数据。区域生源硅生产速率显著低于南大洋可达到的水平，且95%的采样站位中，硅酸浓度均限制了生源硅生产速率。与大西洋亚热带环流区的硅藻相比，本研究区域的硅藻对低浓度硅酸的摄取适应性更弱；在本研究的部分站位，硅动力学限制的强度足以抑制硅藻生长。由此可见，硅酸在北极春季藻华的硅藻动态中发挥着关键作用。硅藻对初级生产的贡献占比存在显著差异，介于<10%至~100%之间，取决于藻华阶段与浮游植物群落组成。尽管本研究关于硅藻细胞输出速率的结果与既往研究一致，但我们观测到的生源硅输出速率显著偏高。若本研究中输出的硅藻物质有更高比例被浮游动物牧食者改造，则可解释这一差异。本研究为欧洲北极海域春季藻华期间硅循环与碳循环的紧密耦合关系提供了迄今为止最直接的证据。