南海北部陆坡区中型浮游动物颗粒食物特性及其对环境变化的响应

Mesozooplankton (200-2000μm) links the microbial food web to the classic food chain and transfer materials and energy from primary producers to higher trophic levels. Eggs and nauplii of MZ are very suitable for larval fish feed, so MZ is the key to support mesopelagic fish resources. Particulate food is the main food sources of mesozooplankton, and its composition and properties are influenced by environmental change, plays very important role in maintaining the mesozoplankton population. Physical process contributes to the large amount of matter and energy exchange between shelf and basin in the slope area, resulting in a large number of zooplankton, mesopelagic fish and other living resource convergence in the slope area. Monsoonal change and mesoscale process influenced the ecological environment in the northern slope of South China Sea, and then the change of particulate food characteristics influenced the MZ population change, reproduction, metabolism and other physiological activities. Therefore, the research of MZ particulate food characteristics is of great significance. By analyzing fatty acids, amino acids and stable isotopes of suspended particulate material in northern slope of South China Sea, we aim to understand the source, nutritional food quality, degradation index and nutritional position of particulate food, and its response to environmental change. The project has propounding ecological significance, which has its potential application in evaluation and rational develop South China Sea fishery resources.

中型浮游动物（200-2000μm）既是海洋初级消费者，也是次级消费者，连接着经典食物链和微食物网。中型浮游动物的卵和早期幼体非常适宜作为仔稚鱼的开口饵料，支撑了南海北部陆坡区中层鱼资源。颗粒食物是中型浮游动物主要食物来源，其组成和性质常受环境变化影响，对南海北部陆坡区浮游动物种群调控起关键作用。南海北部陆坡区具有复杂的环境特征，中尺度过程使得陆架和海盆之间的大量物质和能量交换，从而导致大量浮游动物、中层鱼等海洋生物资源汇聚于陆坡。本项目以南海北部陆坡区悬浮颗粒物为研究对象，使用脂肪酸、氨基酸与稳定同位素三种技术手段，研究中型浮游动物颗粒食物的营养质量、降解指数、食物来源和营养位置，结合多元统计分析探讨颗粒食物特性对环境变化的响应。研究结果有助于深入了解南海北部陆坡区中型浮游动物颗粒食物特性，对认知陆坡区食物网结构和功能，以及合理开发中层鱼资源具有重要的意义。

悬浮颗粒物是中型浮游动物主要食物来源，其组成和性质常受环境变化影响，对南海北部浮游动物种群调控起关键作用。本项目以南海北部浮游动物和悬浮颗粒物为研究对象，使用氨基酸与稳定同位素技术手段，研究了南海北部和西部陆坡区不同粒径中型浮游动物碳氮稳定同位素，探讨了陆源输入对南海北部悬浮颗粒物氨基酸组成和含量的影响，研究结果有助于深入了解南海北部浮游食物网特征及悬浮颗粒物特性。本项目取得的主要结论如下：（1）通过对南海北部关键断面悬浮颗粒物氨基酸特征进行分析，发现关键断面悬浮颗粒物氨基酸受物理水团和生物现场生产双重作用影响，在河口及近岸区域，冲淡水向海输送过程中颗粒物中现场生产力对有机碳的贡献程度不断增大，颗粒物的也变得越来越新鲜。（2）通过对南海北部陆坡区不同粒径浮游动物生物量和稳定同位素进行分析，发现浮游动物碳氮稳定同位素时空差异明显，生物量和氮稳定同位素高值区多分布在珠江径流影响区域、东沙群岛和台湾海峡南部海域。（3）通过对南海西部陆坡区不同粒径浮游动物生物量和稳定同位素进行分析，发现上升流带来底层丰富的营养盐改变了该海区浮游植物的丰度和群落结构，进而影响各粒级浮游动物δ13C值。