Distribution of zooplankton biomass in the southeastern East China Sea

On the basis of the materials collected from six cruises during 1986-1990 in the Kuroshio and its adjacent waters of the East China Sea,the spatial and temporal changes of zooplankton biomass and the relation to certain environmental factors are analysed in this paper.The results indicated that the biomass peaked in autumn,followed by spring and summer and was the lowest in winter.Its horizontal distribution pattern was higher in the continental shelf area than in the Kuroshio area and in the north than in the south of the surveyed area.The higher biomass regions usually occurred in the fronts between different currents and water masses and in the upwelling region of the Kuroshio subsurface water,and were mainly composed of warm-water eurytopic species and tropic oceanic eurytopic species.The relationship between the vertical distribution of zooplankton biomass(Z_w)and water depth(D) might be expressed by the formual LnZ_w=a+bXD.The biomass was observed higher in the upper 100 m.The positive correlation between the biomass of bait-animal and the abundance of larval and juvenile fishes was significant.In addition,the higher biomass region in the northern study area (in the vicinity of 29°N,126°E) overlapped the fishing ground of mackerel and scads in the middle East China Sea.