Lipid Transfers in the Canadian Arctic

MethodologyThe sampling for this dataset took place during summer 2016 between July 29 and October 2. A total of 44 stations were sampled aboard the Canadian icebreaker CCGS Amundsen in different regions of the Canadian Arctic such as Baffin Bay, Nares Strait, Northwest passage, Beaufort Sea and Labrador Sea. Zooplankton was collected with a 1-m2 aperture, 4.5-m long, conical-square plankton net with 200-um mesh size. The samples were subdivided using a Motoda splitting box. The first halves were stored with 4% formaldehyde seawater solution for further count and identification. In the second halves, macrozooplankton were removed and subdivided by size fractioning with a 750 µm mesh in order to select the largest Calanus copepods. The fraction was then subdivided using the Motoda splitting box until reaching ca 1000 mg which was deposited on a pre-burned GF/C filter and stored in pre-burned aluminium foil at -80°C until lipid analysis. The carbon content of copepod species was estimated based on the length-mass relationships established by Forest et al. (2011). At each station, 12L of water was collected at the surface and at the subsurface chlorophyll maximum in Niskin-type bottles mounted on a rosette sampler. A set of probes was used to measure the physico-chemical parameters of seawater. The pH of seawater was measured with a spectrophotometer, nutrient data were analyzed aboard from fresh samples, an aliquot was preserved in Lugol acid for taxonomic analysis and seawater filtration(3L) was conducted for further analyses of lipid contents. Phase separation methods with chloform:methanol:water was used for lipid extractions and lipid classes and fatty acid was determined using thin-layer chromatography and gas chromatography with flame ionization detection.

数据集采样与处理方法：本数据集的采样工作于2016年夏季开展，时间跨度为7月29日至10月2日。研究团队搭乘加拿大破冰船“阿蒙森号”（CCGS Amundsen），在加拿大北极地区的巴芬湾、内尔斯海峡、西北航道、波弗特海以及拉布拉多海等多个区域，对共计44个站位开展采样作业。浮游动物采样采用孔径1平方米、长4.5米的锥方型浮游生物网，网孔尺寸为200微米。样品通过本多分样箱（Motoda splitting box）进行分样。半数样品经4%甲醛海水溶液固定，用于后续计数与物种鉴定。剩余半数样品中移除大型浮游动物后，通过750微米网孔进行粒径分级，以筛选出体型最大的哲水蚤属（Calanus）桡足类。将分级得到的组分再次通过本多分样箱分样，直至样品重量达到约1000毫克，随后将其转移至预灼烧过的GF/C滤膜上，并用预灼烧过的铝箔包裹后置于-80℃环境中保存，直至开展脂质分析。桡足类物种的碳含量基于Forest等人2011年建立的体长-体重关系进行估算。在每个站位，研究人员利用安装在采水器架上的尼斯金型采水瓶（Niskin-type bottles），分别采集表层海水以及亚表层叶绿素最大值层的水样各12升。采用多参数探头测定海水的理化参数。海水pH值通过分光光度计测定；营养盐数据取自新鲜样品并在船上完成分析；分取部分样品经鲁戈氏碘液（Lugol acid）固定后用于分类学分析；另取3升海水进行过滤，用于后续脂质含量分析。采用氯仿-甲醇-水相分离法进行脂质提取，通过薄层色谱法以及配备火焰离子化检测器的气相色谱法，对脂质类别与脂肪酸组成进行测定。