[Seasonal variation and spatial distribution of nutrients and their relationships with harmful algal blooms in coastal area of the East China Sea].

Based on the data from four cruises that carried out in the Changjiang River estuary and its adjacent areas from 2002-04 to 2003-02, the seasonal variation and spatial distribution of nutrients were analyzed, and the relationship between nutrients condition and the harmful algal blooms (HABs) was also discussed. Results showed that the annual average concentration of nutrient was (17.93 +/- 2.46) micromol x L(-1) for DIN, (0.59 +/- 0.11) micromol x L(-1) for PO4(3-) -P, (15.34 +/- 3.23) micromol x L(-1) for SiO3(2-) -Si, and the study area was in the state of eutrophication. The average concentration of nutrient showed a remarkable seasonal fluctuation with the higher value in autumn and winter and lower value in spring and summer. The spatial distribution of the nutrients was typically such that the concentrations of DIN, PO4(3-) -P and SiO3(2-) -Si decreased from inshore to offshore area, and the contours generally decreased rapidly in down-coast directions. DIN and SiO3(2-) -Si of the study area were largely contributed by Changjiang River diluted water and other terrigenous inputs, while PO4(3-) -P mainly by Changjiang River diluted water and the Taiwan Warm Current. The following HABs showed that its occurrences were usually laid in the areas with higher nutrients and lower total suspended particles (TSP).