Size-Fractionated Phytoplankton in the the East China and Southern Yellow Seas and Its Environmental Factors in Autumn 2000

The surface distribution of size-fractioned phytoplankton in the the East China and southern Yellow Seas was discussed as well as the correlations of the size-fractionated chlorophyll a with the environmental factors.The results showed that the chlorophyll a of microplankton(20 μm),nanopl ankton(3～20 μm) and picoplankton(0.45～3 μm) accounted on average for 31.2%,49.0% and 19.8% of the total chlorophyll a in the whole investigated sea area respectively.The microplankton was mainly distributed along the coast of Jiangshu Province, and the high value areas of nanoplankton were focused along the coast of Zhejiang Province and the east of the southern Yellow Sea.The picoplankton was mainly distributed in the middle of the southern Yellow Sea and the southeast of the East China Sea.Correlation analysis of size-fractionated chlorophyll a with environmental factors showed that the correlation coefficients of nutrients with size-fractionated chlorophyll a varied from negative to positive with the increase of the cell size in the investigated sea area,and it indicated the advantage of bigger phytoplankton in high nutrient areas.Close relationships were found among the results of cluster analysis of all stations based on size-fractionated chlorophyll a and environmental factors,the distribution of water currents and the area difference showed by the satellite ocean color remote sensing image.It showed that cluster analysis is a powerful method for studying the relationship between the distribution of phytoplankton and the environmental factors.