Phytoplankton size classes changed oppositely over shelf and basin areas of the South China Sea during 2003-2018
Phytoplankton size classes changed oppositely over shelf and basin areas of the South China Sea during 2003-2018
复制标题
2003-2018年南海陆架和盆地浮游植物大小等级变化相反
DOI：
10.1016/j.pocean.2020.102496
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发表时间：
--
影响因子：
4.1
通讯作者：
Tianyu Wang
中科院分区：
文献类型：
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作者：
Li Teng;Yan Bai;Xianqiang He;Bangyi Tao;Xiaoyan Chen;Fang Gong;Tianyu Wang
浮游植物粒级（PSC）通过影响浮游植物的光合效率、颗粒沉降速率、海洋食物链结构等，与表层碳向深海的输出密切相关。南海作为北太平洋西部最大的边缘海，已有一些关于卫星遥感PSC算法和PSC相关POC输出的研究。南海PSC的长期变化及其对POC输出的影响目前仍知之甚少。在这项研究中，我们构建了一个可靠的长时间序列PSC数据集在SCS通过评估已发表的经验PSC模型的性能。结果表明，在过去的16年（2003-2018年）中，南海陆架区和海盆区的PSC变化相反。在陆架区，微型浮游植物（20-200 µm）的比例显著增加（0.28单位·年-1，p < 0.05）。而在该流域，微微级（<2 µm）浮游植物显著增加（0.19单位·年-1，p < 0.05）。长期PSC变异的驱动因素因南海地区而异。在吕宋海峡西部，与海表温度长期上升相关的过程是影响PSC变化的关键因素;在越南东南部和北方陆架，局地沿岸风和海流对PSC变化起着重要的驱动作用。在PSC变化的背景下，浮游植物初级生产力上升的货架和减少在盆地。同时，在2003-2018年期间，南海真光层深度的POC输出保持稳定。陆架和海盆之间的系统比较将有助于提高对热带边缘海PSC变化和气候变化背景下碳固定的理解。
Phytoplankton size classes (PSC) is closely related to the export of surface carbon to the deep ocean, by affecting the phytoplankton photosynthetic efficiency, particle sinking rate, and the structure of the marine food chain, etc. As the largest marginal sea of the western North Pacific, there have been some researches on satellite-retrieved PSC algorithms and PSC-relative POC export in the South China Sea (SCS), however, long-term changes of PSC and its effect on POC export in the SCS are still poorly understood. In this study, we constructed a reliable long-time series PSC dataset in the SCS by evaluating the performances of published empirical PSC models. Our results revealed opposite changes of PSC on shelf and basin areas of the SCS in the past 16 yrs (2003–2018). Over the shelf regions, the proportion of phytoplankton in micro-size class (20–200 µm) raised significantly (0.28 unit·year−1, p < 0.05). While, in the basin, phytoplankton in pico-size class (<2 µm) increased significantly (0.19 unit·year−1, p < 0.05). The driving factors of long-term PSC variability varied by region in the SCS. Processes related to the long-term rise of sea surface temperature were the key factors in the western areas of the Luzon Strait; in the southeastern areas of Vietnam and the northern shelf, local alongshore winds and currents played important role in driving the PSC changes. In the context of PSC shifts, phytoplankton primary production raised on the shelf and decreased in the basin. Meanwhile, the POC export at euphotic depth in the SCS remained stable during the 2003–2018 period. System comparison between shelf and basin would be helpful to improve the understanding of PSC changes in the tropical marginal seas and carbon fixation in the context of climate change.