Diel asymmetric warming trends, which means nighttime temperature increased faster than daytime temperature, have been reported recently around the world. World-wide, eutrophication has significantly enhanced primary production, especially in shallow lakes. Even with smaller total area than marine ecosystem, shallow lakes play an increasing vital role in the geo-biological-chemical cycling. Our project aims to take Lake Taihu, a representative large shallow eutrophic lakes, as an example, using high frequency monitoring, bioassays and pure cultures. The project is expected to explore the effects of diel asymmetric warming trend on phytoplankton community composition, growth rates and lake ecosystems. The project is also expected to clarify the long-term changes of diel temperatures in Lake Taihu and their impact on phytoplankton community succession, as well as the uptake and release of CO2 by phytoplankton. The results will help clarify how phytoplankton community composition and lake carbon fluxes are altered in response to climatic changes (including asymmetric warming).