Increasing sea surface temperature due to global climate change is a major threat to the growth and survival of many temperate seagrasses, while cold-water upwelling can potentially ameliorate high-temperature stress on temperate seagrass meadows during growing seasons. Seagrasses in the coasts of Korea are increasingly influenced by rising water temperatures and water temperature anomalies in recent decades due to climate change, but the impacts of such events on reproductive phenology of seagrasses remain poorly understood. We investigated the reproductive phenology and sexual reproduction of Zostera marina in four seagrass meadows along the coasts of Korea. Two study sites were located on the south coast where water temperature shows significant warming trends, while two other study sites were located on the east coast where coastal cold-water upwelling is prevalent. Water temperature exhibited stronger seasonality with cooler winter and warmer summer in the south coast sites than in the east coast sites. Cold-water upwelling events occurred frequently along the east coast of Korea, leading to anomalously cool water temperatures during the growing season. Z. marina flowering was prolonged and/or precocious at the east coast sites relative to the south coast sites. The mean flowering period was 5–7.5 months at the east coast sites and 3.5 months at the south coast sites. Moreover, reproductive shoot density and biomass, as well as the corresponding flowering frequency and reproductive efforts were much higher (2–3 times) at the east coast sites than at the south coast sites. Consequently, the potential seed production was higher in the east coast sites than in the south coast sites. Overall, high summer water temperature appeared to reduce sexual reproduction of Z. marina in the south coast sites, while regional cold-water upwelling on the east coast changed seasonal temperature patterns and decreased summer temperature highs, consequently provided a relatively long period of optimal water temperature for production of reproductive shoots. Regional water temperature variability has an important role in shifting the flowering responses of seagrass, which could affect the long-term stability and maintenance of seagrass meadows via the regulation of the sexual-asexual reproductive trade-off.

中文翻译：

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区域水温变化对韩国沿海水域海草带状疱疹开花期物候和有性繁殖的影响

全球气候变化引起的海面温度升高是许多温带海草生长和生存的主要威胁，而冷水上升可能会缓解生长季节温带海草草地上的高温胁迫。由于气候变化，近几十年来韩国沿海海草受到越来越高的水温和水温异常的影响，但此类事件对海草生殖物候的影响仍然知之甚少。我们调查了Zostera marina的生殖物候和有性生殖在韩国沿海的四个海草草甸中。两个研究地点位于南海岸，那里的水温显示出明显的变暖趋势，而另外两个研究地点位于东海岸，那里的沿海冷水上升趋势很普遍。与东部沿海地区相比，南部沿海地区的水温表现出较强的季节性，冬季较凉，夏季较暖。韩国东海岸经常发生冷水上升事件，导致生长季节的凉爽水温异常。Z.玛丽娜相对于南海岸站点，东海岸站点的开花时间延长和/或早熟。东海岸站点的平均开花期为5–7.5个月，南海岸站点的平均开花期为3.5个月。此外，东部沿海地区的繁殖芽密度和生物量以及相应的开花频率和繁殖努力要比南部沿海地区高得多（2-3倍）。因此，东部沿海地区的潜在种子产量高于南部沿海地区。总体而言，夏季水温升高似乎减少了滨海假丝酵母的有性繁殖在南海岸地区，东海岸的区域性冷水​​上升改变了季节性温度模式并降低了夏季温度高点，因此为繁殖芽的生产提供了相对较长的最佳水温。区域水温的变化在改变海草的开花反应中具有重要作用，这可能通过调节有性-无性生殖的权衡而影响海草草甸的长期稳定性和维持性。