琼东上升流区新生产力和f比值对上升流强度的响应与机制

New production is widely used to indicate potential export and atmospheric carbon sequestration to the deep ocean, which is a measure of the efficiency of the biological pump。In terms of marine resources, the f-ratio represents the fraction of the gross primary productivity that can be exploited without affecting the long-term integrity and stability of the ecosystem. Coastal upwelling intensity is regulated by wind speed and direction, which is sensitive to climatic events. Response of upwelling ecosystems to climatic changes is a hot topic in biological oceangraphy. However, the specific response has not been yet completely recognized. Our proposal focuses on response of new production and f-ratio to upwelling intensity in Qiongdong upwelling regime. The field observation will be conducted to examine physical and environmental properties, such as temperature,salinity, current speed and direction, euphotic depth in summer. Meanwhile, 15N trace technology is used to measure the uptake rates of nitrate and ammonium,half saturation constant for nitrate concentration and light intensity. A model will be used to estimate the evolution of new production in Qiongdong upwelling regime over the last two decades, based on parameters observed and sea surface temperature estimated from remote senser. In addition, response of f-ratio to upwelling intensity will be assessed and the underlying mechanisms will be disclosed. The research output will help us to evaluate quantatively changes on the efficiency of carbon sequestration and predict potential marine resources in response to climatic changes in Qiongdong upwelling regime.

新生产力是生物泵效率的一个量度，表征真光层潜在可输出的碳量和大气二氧化碳在深海存储能力，同时也是初级生产力向更高层次营养级的净输出量，为评价次级和更高级营养阶层生物可持续生产提供理论依据。沿岸上升流强度主要受风速、风向调节，对气候事件敏感。上升流生态系统对气候变化的响应是当前海洋科学研究领域的一个重要科学问题。本项目计划以琼东上升流区为主要研究区域，通过现场观测和船上实验，获取关键环境要素和浮游植物对NO3和NH4吸收速率等重要参数，在此基础上，采用新生产力模型和卫星遥感资料（海表温度、风向、风速），重建近十几年琼东上升流区新生产力的年际变化特征，阐明上升流中心区新生产力对气候变化的响应机制。同时探讨上升流强度波动对f比值的调控机制。研究成果有望提升我们对琼东上升流系统固碳水平的认识，也为预测该区域未来渔业资源可持续生产能力提供科学依据。

新生产力是生物泵效率的一个量度，表征真光层潜在可输出的碳量和大气二氧化碳在深海存储能力，同时也是初级生产力向更高层次营养级的净输出量，为评价次级和更高级营养阶层生物可持续生产提供理论依据。然而，我们对新生产力和f比值的调控因子认识存在不足。本项目以琼东上升流及邻近海域作为主要研究区域，开展4个夏季航次的观测，分析了水文环境要素、营养盐动力学、浮游植物生产力和浮游生物生态过程。取得一些研究发现，具体包括：① 厘清了琼东上升流海域环境要素空间变化，② 揭示了琼东上升流区浮游植物氮吸收速率在时空变化；③ 阐明了磷限制对浮游植物氮吸收和f比值的影响机制；④ 现场实测了南海近海亮氨酸与碳转换系数；⑤ 解析了南海细菌碳代谢过程对环境变化的响应机制，⑥ 阐释了海洋水动力过程对原生动物摄食速率的调制作用，⑦ 评估了悬浮颗粒物生物硅检测受岩源硅干扰程度。研究结果表明，新生产力和f比值受水动力过程、营养盐水平和浮游生物生态过程的调控。琼东上升流海域初级生产力以再生生产力为主，f比值小于0.5。琼东上升流近岸海域丰富营养盐供给和层化作用导致高的新生产力和f比值，而外海海域，f比值下降可能与相对高的摄食压力有关。近岸海域磷缺乏导致硝酸盐的吸收优先被限制。锋面或者密度跃层调制浮游生物生态过程，可能影响新生产力和f比值。目前已发表学术论文7篇，其中SCI论文5篇，中文核心期刊论文2篇。