PDF(Pubmed)
Abstract：
Sea-ice microalgae are a key source of energy and nutrient supply to polar marine food webs, particularly during spring, prior to open-water phytoplankton blooms. The nutritional quality of microalgae as a food source depends on their biomolecular (lipid:protein:carbohydrate) composition. In this study, we used synchrotron-based Fourier transform infra-red microspectroscopy (s-FTIR) to measure the biomolecular content of a dominant sea-ice taxa, Nitzschia frigida, from natural land-fast ice communities throughout the Arctic spring season. Repeated sampling over six weeks from an inner (relatively stable) and an outer (relatively dynamic) fjord site revealed high intra-specific variability in biomolecular content, elucidating the plasticity of N. frigida to adjust to the dynamic sea ice and water conditions. Environmental triggers indicating the end of productivity in the ice and onset of ice melt, including nitrogen limitation and increased water temperature, drove an increase in lipid and fatty acids stores, and a decline in protein and carbohydrate content. In the context of climate change and the predicted Atlantification of the Arctic, dynamic mixing and abrupt warmer water advection could truncate these important end-of-season environmental shifts, causing the algae to be released from the ice prior to adequate lipid storage, influencing carbon transfer through the polar marine system.
摘要：
海冰微藻是极地海洋食物网能量和营养供应的关键来源，尤其是在春天,在开放水域浮游植物开花之前。作为食物来源的微藻的营养质量取决于它们的生物分子(脂质:蛋白质:碳水化合物)组成。在这项研究中,我们使用基于同步加速器的傅里叶变换红外显微光谱（s-FTIR）来测量主要海冰分类群的生物分子含量，Nitzschiafrigida,来自整个北极春季的自然陆地快速冰群落。从内部（相对稳定）和外部（相对动态）峡湾位置重复采样六周，显示生物分子含量的高特异性内变异性，阐明N.frigida的可塑性，以适应动态的海冰和水条件。环境触发因素表明冰中生产力的结束和冰融化的开始，包括氮限制和水温升高，推动了脂质和脂肪酸储存的增加，蛋白质和碳水化合物含量下降。在气候变化和北极大西洋化预测的背景下，动态混合和突然变暖的水平流可以截断这些重要的季末环境变化，使藻类在足够的脂质储存之前从冰上释放，影响通过极地海洋系统的碳转移。
