Abstract: The metacommunity model is an effective approach for characterizing the mechanisms in structuring zooplankton community, and a key method for analyzing the process of environmental filtering and spatial diffusion limiting of zooplankton community. To elucidate the processes underlying zooplankton community assembly and to explore seasonal variations in the driving mechanism, a survey across different seasons was conducted at 20 sampling sites in Luoma Lake. A total of 98 zooplankton species, belonging to 23 families and 54 genera, were recorded. The average zooplankton density was 99.5±14.2 ind·L^-1, and the average biomass was 0.837±0.094 mg·L^-1. Dominant species included Brachionus calyciflorus, Asplanchna priodonta, Microcyclops varicans, Mesocyclops leuckarti, Ceriodaphnia quadrangular, and Bosmina longirostris. The structure and diversity of zooplankton communities showed significant seasonal variation (P<0.01). Environmental filtering and dispersal limiting had different effects on community structure of zooplankton across seasons. In spring, autumn, and winter, environmental filtering and spatial diffusion limiting jointly shaped the zooplankton community structure, driven primarily by dissolved oxygen, phosphate, chemical oxygen demand and medium-scale spatial factors (PCNM2, PCNM3, PCNM5, PCNM7, and PCNM8). In summer, however, environmental filtering played a more dominant role, mainly associated with total nitrogen, nitrate, and medium-to-large scale spatial factors (PCNM3 and PCNM5). Overall, environmental filtering plays a leading role in zooplankton community assembly.

Key words: community assembly, environmental filtering, dispersal limitation, seasonal difference