随着富营养条件的加剧，近岸水体浮游植物优势种类型变得单一，浮游动物繁殖所必需的食物营养质量将变得不均衡。初步研究显示亚热带海洋桡足类的繁殖主要受限于多聚不饱和脂肪酸等营养成分。一些以杂食性为主的桡足类会通过捕食小型浮游动物（如纤毛虫和双鞭毛虫等）而获取更多的必需营养物质来完成繁殖及卵的孵化。相反，桡足类对小型浮游动物的捕食强度加大则会间接引起营养级联效应，而减少对浮游植物的控制。意味着，富营养化程度的加剧，浮游植物生物量难以往经典食物链传递。本课题将选取亚热带珠江口和大亚湾两个富营养化近岸水域进行野外实验研究，检验富营养化对食物营养质量的时空变化及其对桡足类繁殖能力的影响，检验富营养化条件下桡足类所引起的营养级联效应及与食物营养质量和杂食性程度的关系，最后比较二个关键营养级相互作用过程受富营养化影响的程度。本课题的开展具有重要的生态意义，并为富营养化治理和维护生态系统健康提供科学依据。

With the development of eutrophication,essential nutritional quality of food for zooplankton reproduction is unbalanced in nature eutrophic waters due to simplified dominant phytoplankton species. Preliminary research indicated that reproduction of subtropical marine copepods is limited by essential nutritional quality such as poly-unsaturated fatty acids. To gain enough essential nutrition, omnivorous copepods can seek for other food items like ciliates and dinoflagellates with containing higher essential fatty acids for copepod egg production and egg hatching. On the other hand, as intensive predation effect on microzooplankton, abundance of microzooplankton will be controlled to some degree and grazing of microzooplankton on phytoplankton will be relieved. Thus, the predation effect induces trophic cascades on phytoplankton, which indirectly increase the abundance of basal food. These processes imply that the increase of eutrophic degree will challenge the classic food chain that the transfer of phytoplankton energy to higher trophic levels is highly limited by their nutritional quality. This project aims to investigate the temporal and spatial variation of food nutritional status to eutrophication and effect of food nutritional quality on reproduction of dominant copepods in estuarine water of Pearl River and coastal water of Daya Bay; and aims to understand the importance of trophic cascades and their strength under increasing eutrophication and increasing omnivory of copepods. At last, the response of the two different directions of trophic interactions to eutrophication will be compared. The project has profound ecological significance, which has its potential application in eutrophication management and maintenance of ecosystem health.