ABSTRACT: Polar regions are facing rapid temperature increase. In Arctic fjord systems, increased temperatures result in hyposalinity caused by the melting of sea ice and glaciers and freshwater run-off. Additionally, enhanced freshwater discharge and intrusion of nutrient-rich Atlantic water may result in nutrient input in summer. Combined, these factors might have a strong impact on primary producers, such as the abundant kelp species Saccharina latissima, an important foundation species in Arctic shallow-water coastal ecosystems. We ran 2 short-term 2factor experiments with field samples from Kongsfjorden (Svalbard) to evaluate the impact of temperature increase in summer combined with hyposalinity (temperature × salinity) or nutrient enrichment (temperature × nutrients) on the physiological and biochemical status of Arctic S. latissima. In the temperature × salinity experiment, growth and maximum photosynthetic quantum yield of photosystem II (F_v/F_m) were generally not affected. Temperature increase resulted in increased C:N ratios, based on decreasing nitrogen assimilation. Overall, hyposalinity had no severe effect but resulted in lower phlorotannin concentrations. Growth and F_v/F_m improved with increasing temperatures and nutrient enrichment. The de-epoxidation state of the xanthophyll cycle and mannitol declined at higher temperatures. Regarding other biochemical response variables, nutrients had no major impact (temperature × nutrients). In conclusion, in line with its broad latitudinal distribution range and adaptability, S. latissima proved to be highly resilient to changing abiotic drivers and will likely be promoted by warming in the future Arctic.

中文翻译：

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应对不断变化的北极：斯匹次卑尔根州的棕色海藻Saccharina latissima的驯化机制

摘要：极地地区正面临着迅速的升温。在北极峡湾系统中，升高的温度导致海冰和冰川融化以及淡水径流引起的次盐度降低。此外，增强的淡水排放和富含营养的大西洋水的入侵可能会导致夏季输入营养。综合考虑，这些因素可能对初级生产者产生重大影响，例如丰富的海带物种Saccharina latissima是北极浅水沿海生态系统中的重要基础物种。我们使用来自Kongsfjorden（斯瓦尔巴特群岛）的田间样品进行了2个短期2因子实验，以评估夏季温度升高以及盐度过低（温度×盐度）或营养盐富集（温度×营养盐）对北极S生理生化状况的影响。latissima。在温度×盐度实验中，光系统II（F _v / F _m）的生长和最大光合量子产率通常不受影响。基于减少的氮同化，温度升高导致C：N比增加。总体而言，低盐度无严重影响，但导致降低的金环宁浓度。成长与F_v / F _m随着温度升高和养分富集而提高。叶绿素循环和甘露醇的脱环氧化状态在较高温度下下降。关于其他生化响应变量，养分没有重大影响（温度×养分）。总之，鉴于其广泛的纬度分布范围和适应性，S。latissima被证明对不断变化的非生物驱动器具有高度的适应能力，并且有可能在未来的北极变暖中得到促进。