The sugar kelp Saccharina latissima experiences a wide range of environmental conditions along its geographical and vertical distribution range. Temperature and salinity are two critical drivers influencing growth, photosynthesis and biochemical composition. Moreover, interactive effects might modify the results described for single effects. In shallow water coastal systems, exposure to rising temperatures and low salinity are expected as consequence of global warming, increased precipitation and coastal run‐off. To understand the acclimation mechanisms of S. latissima to changes in temperature and salinity and their interactions, we performed a mechanistic laboratory experiment in which juvenile sporophytes from Brittany, France were exposed to a combination of three temperatures (0, 8 and 15°C) and two salinity levels (20 and 30 psu (practical salinity units)). After a temperature acclimation of 7 days, sporophytes were exposed to low salinity (20 psu) for a period of 11 days. Growth, and maximal quantum yield of photosystem II (Fv/Fm), pigments, mannitol content and C:N ratio were measured over time. We report for the first time in S. latissima a fivefold increase in the osmolyte mannitol in response to low temperature (0°C) compared to 8 and 15°C that may have ecological and economic implications. Low temperatures significantly affected all parameters, mostly in a negative way. Chlorophyll a, the accessory pigment pool, growth and Fv/Fm were significantly lower at 0°C, while the de‐epoxidation state of the xanthophyll cycle was increased at both 0 and 8°C compared to 15°C. Mannitol content and growth decreased with decreased salinity; in contrast, pigment content and Fv/Fm were to a large extent irresponsive to salinity. In comparison to S. latissima originating from an Arctic population, despite some reported differences, this study reveals a remarkably similar impact of temperature and salinity variation, reflecting the large degree of adaptability in this species.

中文翻译：

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温度和盐度对糖海带 Saccharina latissima 生理性能的调节

糖海带 Saccharina latissima 在其地理和垂直分布范围内经历了广泛的环境条件。温度和盐度是影响生长、光合作用和生化成分的两个关键驱动因素。此外，交互效果可能会修改为单个效果描述的结果。在浅水沿海系统中，由于全球变暖、降水增加和沿海径流，预计会暴露于升高的温度和低盐度。为了了解 S. latissima 对温度和盐度变化及其相互作用的适应机制，我们进行了一项机械实验室实验，其中来自法国布列塔尼的幼年孢子体暴露于三种温度 (0, 8 和 15°C）和两个盐度水平（20 和 30 psu（实际盐度单位））。在温度适应 7 天后，孢子体暴露于低盐度 (20 psu) 下 11 天。随着时间的推移测量光系统 II (Fv/Fm) 的生长和最大量子产率、色素、甘露醇含量和 C:N 比。我们首次报告了在 S. latissima 中，与可能具有生态和经济影响的 8 和 15°C 相比，低温 (0°C) 时渗透剂甘露醇增加了五倍。低温显着影响了所有参数，主要是负面影响。0°C 时叶绿素 a、辅助色素库、生长和 Fv/Fm 显着降低，而与 15°C 相比，0°C 和 8°C 下叶黄素循环的去环氧化状态均增加。甘露醇含量和生长随盐度降低而下降；相比之下，色素含量和 Fv/Fm 在很大程度上与盐度无关。与源自北极种群的 S. latissima 相比，尽管报告了一些差异，但这项研究揭示了温度和盐度变化的非常相似的影响，反映了该物种的高度适应性。