Abstract:The distribution of zooplankton in the area of radiate sand ridges in north Jiangsu shoal was investigated during May and September in 2012.The relationship between the distribution of zooplankton,topography and some other environmental factors were analyzed by using indicators and methods of gathering strength,variance contribution,dominance index,stepwise regression,etc..The results showed that both of the biomass and abundance of zooplankton have obvious seasonal variation.Spatially,the quantity of zooplankton was higher in sand ridges than that in tidal creeks.In spring,the average biomass of different areas were 606.63 mg/m3(sand ridges),428.00 mg/m3(shallow tidal creeks)and 178.55 mg/m3(deep tidal creeks).The average abundance were 560.76 ind/m3(sand ridges),389.39 ind/m3(shallow tidal creeks)and 161.28 ind/m3(deep tidal creeks).However,in autumn,the average biomass of different areas were 208.01 mg/m3(sand ridges),181.30 mg/m3(shallow tidal creeks)and 60.47 mg/m3(deep tidal creeks).And the average abundance were 184.15 ind/m3(sand ridges),56.42 ind/m3(shallow tidal creeks)and 112.14 ind/m3(deep tidal creeks).The study showed that the Copepods was predominant species in two seasons.The research indicated that the distribution of zooplankton was associated with topography and tidal waves in the north Jiangsu shoal.Some reasons can explain it.Firstly,the water velocity was influenced by the topography,where the water velocity was higher in sand ridges than tidal creeks.Secondly,the East China Sea tidal wave and the South Yellow Sea tidal wave converged in north Jiangsu shoal.Sediment can be deposited easily in low flow velocity water,and upwelling waters brought a wealth of nutrients.It would be beneficial to the aggregation and feed of zooplankton,which lead to high biomass and abundance of zooplankton in sand ridges.The dominant species tend to be highly aggregated,which contributed to the main component of economic fishes' bait.The food availability and quality of north Jiangsu shoal were higher than other water areas,which played a crucial role in the formation of Lüsi Fishing Ground.