Coastal water temperature anomalies are expected to intensify during the current period of global climate change. Sudden water temperature elevation (e.g., heat waves) or decrease (e.g., summer upwelling) can have a far-reaching influence on seagrasses in temperate regions. We examined the influence of anomalously elevated and decreased water temperatures on the growth of Zostera marina plants held under two different levels of irradiance. Core samples of wild Z. marina shoots were cultured under either suddenly elevated (from the in situ level of 20 to 27 °C during the fall experiment) or decreased (from the in situ level of 27 to 20 °C during the summer experiment) temperature. We included light as an experimental factor because the light requirements of seagrasses increase when plants are under thermal stress. The growth of Z. marina shoots under anomalously elevated water temperature conditions, which simulated marine heat waves, was significantly declined, whereas the plant growth under suddenly decreased water temperature conditions, which simulated summer upwelling events, was maintained or slightly increased. In the fall 2014 experimental period, Z. marina shoots under the suddenly elevated water temperature condition (27 °C) showed significant decreases in shoot density, biomass, and leaf productivity by ca. 40–80%, whereas plants held under the ambient water temperature condition (20 °C) maintained or slightly increased their growths. In the summer 2015 experimental period, Z. marina under the sudden temperature reduction conditions (20 °C) maintained relatively high shoot density and leaf productivity, whereas plants under the in situ high water temperature condition (27 °C) showed significantly reduced growths. The growth of Z. marina shoots, which were cultured in the optimal temperature condition (20 °C), was enhanced by increasing underwater irradiance. However, the adverse effects of high water temperature on Z. marina growth could not be reversed by increasing irradiance levels at the end of the experiments. According to the results of this study, the intensified sea surface water temperature anomalies induced by global climate change will alter the growth and distribution of temperate seagrasses and, consequently, the structure and function of the coastal seagrass ecosystems in the temperate region.

中文翻译：

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水温异常对高低照度条件下滨海带状植物生长的影响

在当前全球气候变化时期，沿海水温异常有望加剧。水温突然升高（例如，热浪）或温度降低（例如，夏季上升流）可能会对温带地区的海草产生深远的影响。我们检查了异常升高和降低的水温对在两种不同水平的辐照下保持的滨海带状疱疹植物生长的影响。野生Z.marina的核心样品将芽培养在突然升高的温度（秋季实验期间原位水平从20到27°C）或降低的温度（夏季实验中原位水平从27到20°C）下进行培养。我们将光作为实验因素，因为当植物处于热胁迫下时，海草的光需求会增加。的生长叶藻枝条异常升高水的温度条件下，该模拟海洋热浪，被显著下降，而下的植物生长突然减小水的温度条件，这模拟夏天上升流事件，维持或略有增加。在2014年秋季的实验期间，Z。marina在突然升高的水温条件下（27°C），新芽显示出新芽密度，生物量和叶片生产力均显着下降了约20％。40–80％，而处于环境水温条件下（20°C）的植物则保持或略有增长。在2015年夏季的实验期内，突然降低温度的条件（20°C）下的滨海假单胞菌保持了较高的枝条密度和叶片生产力，而在原位高水温条件下（27°C）的植物生长明显降低。的生长叶藻枝条，将其在最佳温度条件（20℃）培养，通过水下辐照度增加增强。然而，高水温对水的不利影响在实验结束时，不能通过增加辐照度来逆转滨海假单胞菌的生长。根据这项研究的结果，全球气候变化引起的海表水温异常加剧将改变温带海草的生长和分布，从而改变温带地区沿海海草生态系统的结构和功能。