Sea level rise and more frequent storm and precipitation events associated with climate change are predicted to increase salinity fluctuations in estuarine and inshore areas, where foundation species such as eelgrass (Zostera marina L.) will be exposed to more frequent salinity changes. Effects of acute hyposalinity exposure on seagrasses remain poorly understood compared to the effects of more prolonged, constant salinity. Here, we examined growth and photo-physiological responses of Z. marina to 5 levels of stable salinity (5, 12 19, 25, 33) and compared effects of prolonged (16 days) versus acute (24 and 48 hours) exposure to hyposalinity (salinity 5 and 12) using fluorescence imaging. We also examined if fluorescence kinetics were affected by age differences across leaves. Growth reached an optimum at salinity 19 and was more affected by hyposalinity than hypersalinity. Rapid reduction from salinity 25 to 5 decreased the maximum quantum yield (F_v/F_m) after just 48 h. In contrast with prolonged exposure, non-photochemical quenching processes were not increased at salinity 5 after 48 h. Young leaves were more susceptible to extreme hyposalinity than older leaves (e.g., lower photosynthetic quantum yield), which emphasizes the importance of considering shoot-scale and within-shoot variations in studies of stress response patterns. Differences between hyposalinity and hypersalinity responses were generally replicated in the literature, but we were not able to detect any differences across studies. Overall, these results suggest that eelgrass is tolerant to large fluctuations in salinity, but sudden extreme reductions may act as a severe co-stressor, and contribute to accumulated stress-exposure effects (chronic or lasting effects).

预计海平面上升以及与气候变化有关的更频繁的风暴和降水事件会增加河口和近岸地区的盐度波动，在这些地区，诸如鳗el（Zostera marina L.）等基础物种将面临更频繁的盐度变化。与更长，持续盐度的影响相比，急性低盐度暴露对海草的影响仍然知之甚少。在这里，我们检查了Z. marina的生长和光生理反应达到5个稳定盐度水平（5、12、19、25、33），并使用荧光成像比较了长​​期（16天）与急性（24和48小时）暴露于低盐度（盐度5和12）的影响。我们还检查了荧光动力学是否受叶片间年龄差异的影响。在盐度为19时，生长达到最佳状态，次高盐度比高盐度受到的影响更大。从盐度25迅速降低至5降低了最大量子产率（F _v / F _m）仅48小时。与长时间暴露相反，在48小时后，盐度为5时，非光化学猝灭过程并未增加。幼叶比老叶更易受极端次盐度的影响（例如，较低的光合作用量子产率），这强调了在胁迫响应模式研究中考虑枝条尺度和枝内变化的重要性。低盐度和高盐度反应之间的差异通常在文献中重复出现，但我们无法在研究之间发现任何差异。总体而言，这些结果表明鳗e可耐受盐度的大幅度波动，但突然的极端减少可能会成为严重的共同应激源，并导致累积的压力暴露效应（长期或持久效应）。