Abstract: To evaluate the seasonal distribution of macrozoobenthos and its relations to environmental factors in Oujiang River estuary and adjacent waters, two cruise surveys were conducted in May 2006 (spring) and January 2007 (winter). A total of 65 species were collected, among which, polychaeta and mollusk were the dominant groups,  Capitella capitata and Nassarius succinctus were the dominant species in spring and winter, respectively. The species number of macrozoobenthos was more in adjacent sea area than in estuary, and more in spring than in winter. The average biomass and density in the two seasons were 1966 g·m-2 and 131 ind·m-2, respectively. There was a significant difference in the macrozoobenthos density between the two seasons, while less difference was observed in the biomass. The Shannon-Weiner index had significant difference between the two seasons, while Pielou eveness index, Margalef abundance index, and Simpsom dominance index had not. Water temperature and phytoplankton were the key factors affecting the macrozoobenthic taxa in spring, and water total organic carbon and dissolve oxygen were the key affecting factors in winter.

Key words: Oujiang River estuary, macrobenthos, canonical correspondence analysis, long term fertilization, upland yellow soil, maize, fertilizer utilization rate.