随着人类生产活动排放CO2的增加，预计到本世纪末大气中CO2浓度将翻倍，可能会对水体中初级生产者的诱发性防御产生重大效应，进而可能直接影响到食物网并危及到水域生态系统的稳定性。本申请项目将采用室内模拟实验和生态模型相结合的方法，把不同藻类分别置于多种CO2水平和温度梯度下，在浮游动物的间接或直接牧食作用下，通过检测藻类在不同CO2水平及温度条件下的生存状况、诱发性防御程度、营养质量等方面的变化，确定由此对下一营养级浮游动物的影响以及藻类与浮游动物种群的相互动态关系；然后把上述试验获得的藻类和浮游动物的各种相关生态生理学响应参数置于STELLA模型，通过赋予模型中CO2水平和温度的变化来模拟食物链中藻类和浮游动物种群动态关系对气候变化的响应，预测对食物网稳定性的影响及水域生态系统可能出现的变化趋势；同时分离并鉴定起诱导作用的信息素，确定CO2水平和温度上升对信息素稳定性的影响。

The atmospheric carbon dioxide concentration is expected to reach double the pre-industrial level by the end of the century with the increasing carbon dioxide emission due to human activities. This may have considerable impact on the inducible defences of primary producers in water and then probably further affect the stability of food web and aquatic ecosystem. The proposal will combine laboratory experiments and ecological model to study the responses of inducible defences in algae to elevation of carbon dioxide level and temperature and its ecological implications. Firstly, the different model species of algae will be exposed to direct and indirect grazing of zooplankton under multiple levels of carbon dioxide and temperatures; then the multiple parameters of sampled algae will be measured, including viability, growth, inducible defences, morphological and ultrastructural characteristics of colonies, biochemical composition, photosynthesis parameters, and nutritional quality of algae as food for zooplankton, which can reveal the influences of changes in algae on zooplankton of higher trophic level and interspecific interactions of algae and zooplankon. Secondly, the eco-physiological parameters of algae and zooplankton obtained from the laboratory experiments will be input to STELLA population model and run under different carbon dioxide concentrations and temperatures. From the model, we can simulate the responses of population dynamics of algae and zooplankton in food chain to climate change and predict the influence on stability of food web and the probable change trend of aquatic ecosystem. Finally, the kairomone which mediates inducible defences will be isolated and determined; the effects of elevation of carbon dioxide level and temperature on the stability of kairomone will also be studied.