<p>2021 OceanMet summary.</p>

Phytoplankton form the base of the food web and act as the main source of both energy, and ω3 essential fatty acids in marine ecosystems. In the Arctic, the effects of climate change are exacerbated compared to lower latitudes. Expected shifts in phytoplankton growth due to climate change in the Arctic are dependent on water physicochemistry, especially temperature, salinity, and nutrient concentrations. The goal of this investigation was to, 1) assess which Canadian Arctic (CA) regions were significantly different based on biomarkers of phytoplankton condition and community assemblage, and 2) identify which hydrographic properties and dissolved inorganic nutrient concentrations correlated with those biomarkers. Phytoplankton samples were collected from the CA in 2019 (July-September) and 2021 (August-October). CA regions were clustered based on similar hydrographic properties, and then lipid and FA profiles were compared. In 2019, there was variation in monounsaturated fatty acid (MUFA) proportions: cluster groups in very deep water, with higher temperature and lower oxygen saturation (Davis Strait stations) were significantly lower compared to cluster groups defined by lower salinity and light transmission (East Barrow Strait and Lancaster Sound stations) in both surface (p = 0.001) and sub-surface chlorophyll maximum waters (SCM)(p = 0.008). In 2021, a year with more expansive coverage of the CA compared to 2019, Σω3% and polyunsaturated fatty acids (PUFA) were significantly higher in cluster groups containing Baffin Bay stations compared to the clusters defined by lower salinity (Beaufort Sea and the Canadian Arctic Archipelago stations) in both surface (p < 0.001) and SCM waters (p < 0.001). Across both years and both SCM and surface waters, DHA/EPA (two ω3 essential fatty acids) negatively correlated with phosphate. Overall, FA proportions in the CA are strongly affected by physiochemical conditions in late summer with MUFA responding mainly to physical changes, while PUFA responded heavily to phosphate changes.浮游植物（Phytoplankton）是食物网的基础，同时也是海洋生态系统中能量与ω3必需脂肪酸（ω3 essential fatty acids）的主要来源。在北极地区，气候变化的影响较低纬度地区更为加剧。北极地区因气候变化引发的浮游植物生长预期变化，取决于水体的物理化学特性，尤其是温度、盐度与营养盐浓度。本研究的目标为：1）基于浮游植物状态与群落组成的生物标志物，评估哪些加拿大北极（Canadian Arctic, CA）区域存在显著差异；2）明确哪些水文特性与溶解态无机营养盐浓度与上述生物标志物存在相关性。 研究于2019年（7月至9月）与2021年（8月至10月）在加拿大北极区域采集浮游植物样本。研究人员基于相似的水文特性对加拿大北极区域进行聚类，随后对比各聚类组的脂质与脂肪酸（fatty acids, FA）谱图。 2019年，单不饱和脂肪酸（monounsaturated fatty acid, MUFA）占比存在差异：在表层水体（p=0.001）与亚表层叶绿素最大值水体（Subsurface Chlorophyll Maximum, SCM，p=0.008）中，位于深水、温度较高且氧饱和度较低的聚类组（戴维斯海峡站位）的MUFA占比，显著低于以低盐度与透光性为特征的聚类组（东巴罗海峡与兰开斯特海峡站位）。 2021年（该年度加拿大北极区域的采样覆盖范围较2019年更广），在表层水体（p<0.001）与SCM水体（p<0.001）中，包含巴芬湾站位的聚类组的总ω3脂肪酸占比（Σω3%）与多不饱和脂肪酸（polyunsaturated fatty acids, PUFA）占比，显著高于以低盐度为特征的聚类组（波弗特海与加拿大北极群岛站位）。 在两年的表层与SCM水体样本中，二十二碳六烯酸/二十碳五烯酸（DHA/EPA，两种ω3必需脂肪酸）占比与磷酸盐浓度呈显著负相关。总体而言，加拿大北极区域的脂肪酸占比在夏末受水体物理化学条件的显著影响：单不饱和脂肪酸主要响应物理环境变化，而多不饱和脂肪酸则主要受磷酸盐浓度变化的调控。