Arctic fjord systems experience large amplitudes of change in temperature and radiation regime due to climate warming and the related decrease in sea ice. The resultant increase in irradiance entering the water column influences photosynthetic activity of benthic and pelagic primary producers. The subtidal brown alga Desmarestia aculeata and the intertidal red alga Palmaria palmata populate the cold-temperate coasts of the North Atlantic, reaching the polar zone. To evaluate their acclimation potential, we collected both species in Kongsfjorden, Svalbard (78.9°N, 11.9°E), during the Arctic summer and exposed specimens to two different PAR levels (50 and 500 μmol photons m⁻² s⁻¹) and temperatures (0, 4 and 8 °C) for 21 days. Photosynthetic parameters and biochemical features (pigment concentration and antioxidants) were assessed. In general, high irradiance was the factor that generated a negative effect for D. aculeata and P. palmata in the photosynthetic parameters of the photosynthesis–irradiance curve and F_v/F_m. The pigment concentration in both species tended to decrease with increasing irradiance. Antioxidant level showed different trends for both species: in D. aculeata, antioxidant potential increased with high irradiance and temperature, while in P. palmata, it only increased with high irradiance. Both species showed responses to the interaction of irradiance and temperature, although D. aculeata was more sensitive to high irradiance than P. palmata. Our study shows how these species, which have similar geographical distribution in the North Atlantic and the Arctic but belong to different taxonomic lineages, have similar strategies of acclimation, although they respond differently to ecophysiological parameters.

由于气候变暖和相关的海冰减少，北极峡湾系统的温度和辐射状况发生了大幅变化。进入水体的辐照度增加会影响底栖和远洋初级生产者的光合作用活动。潮下带褐藻 Desmarestia aculeata 和潮间带红藻 Palmaria palmata 分布在北大西洋的冷温带海岸，到达极地地区。为了评估它们的适应潜力，我们在北极夏季期间在斯瓦尔巴群岛的 Kongsfjorden（78.9°N，11.9°E）收集了这两种物种，并将标本暴露于两种不同的 PAR 水平（50 和 500 μmol 光子 m ^-2  s ^-1) 和温度（0、4 和 8 °C）持续 21 天。评估了光合参数和生化特征（色素浓度和抗氧化剂）。一般而言，高辐照度是对刺参 和 掌叶松 的光合作用-辐照度曲线和F _v / F _m的光合参数 产生负面影响的因素 。两种物种的色素浓度都随着辐照度的增加而降低。两种物种的抗氧化水平显示出不同的趋势：在 D. aculeata 中，抗氧化潜力随着高辐照度和温度而增加，而在 P. palmata，它只会随着高辐照度而增加。两种物种都对辐照度和温度的相互作用表现出反应，尽管 D. aculeata 比P. palmata对高辐照度更敏感 。我们的研究表明，这些在北大西洋和北极具有相似地理分布但属于不同分类谱系的物种如何具有相似的适应策略，尽管它们对生态生理参数的反应不同。