Abstract: The zooplankton community characteristics were studied in the Nanhu Lake ecosystem of Changchun in 2001～2002. 94 Species of zooplankton were found, including 51 species of Rotifera. The seasonal changes of dominant zooplankton species were obvious. Twice peaks of zooplankton individual number were found in summer and autumn. The annual net and gross productions of zooplan kton were 704.45 kJ·m^-2and 1 642.50 kJ·m^-2， respectively. The annual gross production of zooplankton was 13.9% of annual net produ ction of phytoplankton. The P/B index of zooplankton community was 41.4（c alculated by P_n）or 96.4（calculated by P_g）. Based on the determination result of in situ experiment, the grazing abilities of zooplankton community on phytoplankton and bacteriaplankton were 2.57 kJ·m^-2·h^-1 and 1.47 μg C·L^-1·h^-1 respectively, which were 51.7% of phytoplankton net productivity and 32.9% of bacteriaplan kton net productivity in the same period. The carbon amount forming zooplankton net productivity was 8.2% of the total carbon amount fixed by phytoplankton. The zooplankton community indicates, to some extent, the feature of the Nanhu Lake as an eutrophicated lake in tem perate zone.

Key words: zooplankton, community characteristic, aquatic ecosystem, Nanhu Lake of Changchun