Abstract: A two cruises investigation on the meiobenthos in the continental shelf of Southern Yellow Sea was made in January 2003 and January 2004. The results showed that the average abundance of meiobenthos was (954.20±269.47) ind·10 cm^-2 and (1 186.12±486.07) ind·10 cm^-2, and the biomass was (954.38±403.93) μg·10 cm^-2 and (1 120.72±487.21) μg·10 cm^-2 in January 2003 and January 2004, respectively, with no significant difference observed. A total of twenty meiobenthic groups were identified. Free-living marine nematodes was the most dominant group in abundance, with a relative dominance of 87% in 2003 and 90% in 2004, followed by benthic harpacticoids copepoda, polychaeta and kinorhyncha. In terms of biomass, the dominant groups were nematoda (34%—38%), polychaeta (25%—33%), ostracoda (9%—22%) and copepoda (8%). 96.64% of the meiobenthos distributed in the top 0—5 cm of sediment, while 72.48% of nematode and 89.46% of copepoda were in the top 0—2 cm of the sediment. Meiob-enthos biomass had significant correlation with the sand and silt contents of sediment and the content of Chla. The species composition and biodiversity analyses of six representative stations indicated that there were three meiobenthos communities in the study area, i . e ., inshore, cold waters mass, and transitional communities.

Key words: Pine wilt disease, Pinewood nematode, Ecology, Pathogenic mechanism, Pest management