The role of food availability and phytoplankton community dynamics in the seasonal succession of zooplankton community in a subtropical reservoir

Seasonal patterns of zooplankton succession have been explained by physical factors such as temperature and precipitation. While the influence of biological factors, such as food availability and composition, has been recognized in theory and studies in some temperate lakes, how food availability and composition affect the seasonal succession of zooplankton communities, especially in tropical/subtropical lakes, is still unclear and under debate. In this study, we applied multivariate analyses to a 3-year time series of physicochemical factors, various food sources (primary and bacterial production), and phytoplankton and zooplankton species composition in a subtropical reservoir in Taiwan. Our results demonstrated that (i) in addition to physical factors, seasonal variation of food availability partly explains zooplankton seasonal succession. In particular, inter-annual variation of food availability proved more important than physical factors in determining the inter-annual variation in zooplankton populations. Specifically, limited food supply amplifies the amplitude of seasonal variation of zooplankton community biomass and composition; (ii) the association between zooplankton and phytoplankton was stronger when regarding their species composition than when regarding their biomass, implying a strong interaction between zooplankton and phytoplankton at the community level.