In early spring, a hydrological front emerges in the central Yellow Sea,resulting from the intrusion of the high temperature and salinity Yellow Sea Warm Current (YSWC).The present study, applying phytoplankton pigments and flow cytometry measurements in March of 2007 and 2009, focuses on the biogeochemical effects of the YSWC.The nutrients fronts were coincident with the hydrological front,and a positive linear relationship between nitrate and salinity was found in the frontal area.This contrast with the common situation of coastal waters where high salinity values usually correlate with poor nutrients.We suggested nutrient concentrations of the YSWC waters might have been enhanced by mixing with the local nutrient-rich waters when it invaded the Yellow Sea from the north of the Changjiang estuary.