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\10,123,000 (FY1998: \2,014,000)
To evaluate the influence on chlorophyll a (chl-a) distribution of the load from land discharges, a database of chl-a and related oceanographic parameters was constructed from 32 previous survey cruises in the East China Sea. The database consisted of chl-a, temperature and salinity for 32 cruises, transparency for 26 cruises and nutrients for 7 cruises. Also, Chl-a distribution and hydrography were observed in summer 1997 and in autumn 1998. The study area consisted of low-salinity waters from the Changjiang River and other continental shelf waters. The vertical profile of chl-a showed a peak in a subsurface layer throughout the study area. Chl-a concentration in surface waters in the Changjiang plume was higher than at the other sites. The highest chl-a concentrations were distributed in the subsurface layer between the low-salinity surface waters and the underlying Yellow Sea Bottom Cold Waters. The subsurface chl-a maximum was related to the thermocline. The depth of the subsurface chl-a maximum was calculated as one of the parameters in a function to represent the profile features. These depths showed a tendency to increase southeastward from the low-salinity waters, suggesting that the latter and vertical stratification might influence chl-a distribution in the East China Sea. The relationship between surface chl-a and salinity in summer 1997 and in the database showed that the surface chl-a levels in the lowsalinity waters were higher in the Chanjiang estuary than in the other shelf waters. Therefore, the majority of nutrients supplied from the River might be exhausted by phytoplankton in the Changjiang estuary in summer.
chlorophyll-a, East China Sea, database, hydrography.