This study was carried out from 19 to 26 May 2003, on
board R/V Zhe Hai Huan Jian. A total of 29 stations were
established over two intersected transects identified as A
and B (Fig. 1). Transect A extended from the freshwater
river to the saltwater sea covering almost the whole salinity
gradient; transect B ran across the edge of the bar area
(Chen et al., 1999) and covered the whole river mouth. At
Stations 13 and 20 (anchor stations)