Distribution characteristics of zooplankton biomass in the East China Sea

On the basis of the data of oceanographic survey in the East China Sea in four seasons during 1997-2000 (23degrees30'-33degrees00'N, 118degrees30'similar to128degreesE), the variation of total biomass and diet biomass of zooplankton and their spatial-temporal distribution and relationship with the fishing ground of Engraulisjaponicus are approached and analyzed. The results show that the average biomass is 65.32 mg/m(3) in four seasons, autumn (86.18 mg/m(3)) being greater than summer (69.18 mg/m3) greater than spring (55.67 mg/m(3)) greater than winter (50.33 mg/m(3)). The average value of diet zooplankton biomass is 40.9 mg/m(3). The trends of horizontal distribution both in the total biomass and the diet biomass of zooplankton are similar. The high biomass region (250similar to500 mg/m(3)) is very limited, only accounting for 1% of the investigation area. Seasonal variation of the biomass is very remarkable in the west and north parts of East China Sea coastal waters (29degrees30'N, 125degreesE). The horizontal distribution of diet zooplankton depends on the abundance distribution of crustacean. The distribution of diet zooplankton is related to the fishing ground of Engraulisjaponicus and the high-density area of young fish and larval. In spring, the central fishing ground of Engraulisjaponicus (>100 kg/h) and the high-density area of young fish and larval (>100 individuals per net) are located at the same place of high-density (100similar to250 mg/m(3))area of diet zooplankton in the middle-southern part of East China Sea or the edge of its waters.