Liaoning Ocean and Fisheries Science Research Institute, Dalian, Liaoning, 116023, China; Nanjing University of Information Science & Technology, Nanjing, Jiangsu, 210044, China.
Liaoning Ocean and Fisheries Science Research Institute, Dalian, Liaoning, 116023, China.
Mar Environ Res. 2024 Nov;202:106815. doi: 10.1016/j.marenvres.2024.106815. Epub 2024 Oct 28.
Nutrients are essential for marine primary productivity and have a critical role in maintaining the structure and function of marginal. Variations in nutrient levels in sea ecosystems can influence ecological disturbances significantly. The Liaodong Bay (LDB) is a semi-enclosed marginal sea in northern China. It has experienced severe eutrophication since the 1990s, leading to considerable environmental challenges. Understanding of seasonal and long-term nutrient dynamics in the LDB is limited. We examined seasonal datasets collected in May (spring), August (summer), November (autumn), and March (winter) of 2019, and analyzed long-term trends through historical records spanning multiple decades. Nutrients accumulated during autumn/winter but were depleted during spring/summer. A low concentration of dissolved inorganic phosphate led to an increased nitrogen ratio exceeding the Redfield ratio (>16) during winter, spring, and summer, driven by phytoplankton growth. In late-autumn, nutrient concentrations increased, with ratios approaching the Redfield ratio. Phosphorus limitation prevailed in spring, summer, and winter, while silicon limitation dominated in autumn. Dissolved inorganic nitrogen and nitrogen ratios in the LDB increased sharply since the 1980s, peaking before declining after 2013. Dissolved silica and silicon ratios decreased steadily, stabilizing in recent years. These trends imply a shift from nitrogen-to-phosphorus limitation, influenced by riverine inputs and atmospheric deposition. These nutrient fluctuations may have significant ecological effects, including dinoflagellate abundance, algal blooms, and jellyfish blooms. Our analyses highlight the complexity of nutrient dynamics and positive impact of local nutrient-reduction policies implemented in recent years in improving the environmental quality of the LDB.
营养物质是海洋初级生产力的基础，对维持边缘海生态系统的结构和功能具有关键作用。海洋生态系统中营养盐水平的变化会显著影响生态干扰。辽东湾（LDB）是中国北方的一个半封闭边缘海。自 20 世纪 90 年代以来，它经历了严重的富营养化，导致了相当大的环境挑战。对 LDB 中季节性和长期营养动态的了解有限。我们研究了 2019 年 5 月（春季）、8 月（夏季）、11 月（秋季）和 3 月（冬季）采集的季节性数据集，并通过跨越数十年的历史记录分析了长期趋势。营养物质在秋季/冬季积累，但在春季/夏季耗尽。冬季、春季和夏季，由于浮游植物的生长，溶解无机磷酸盐浓度低导致氮比超过红比值（>16），这导致了营养盐的增加。在晚秋，营养盐浓度增加，比值接近红比值。春季、夏季和冬季磷限制为主，秋季硅限制为主。LDB 中的溶解无机氮和氮比自 20 世纪 80 年代以来急剧增加，2013 年后先增加后减少。溶解硅和硅比稳定下降，近年来稳定。这些趋势表明，氮磷限制的转变受到河流输入和大气沉积的影响。这些营养盐波动可能对海洋生态系统产生重大影响，包括甲藻丰度、藻类水华和水母水华。我们的分析强调了营养动态的复杂性，以及近年来实施的局部减少营养物质政策对改善 LDB 环境质量的积极影响。
