[Ecological characteristics of Prorocentrum dentatum and the cause of harmful algal bloom formation in China Sea].

Large-scale harmful alga bloom (HAB) has been found in Changjiang River estuary and Zhoushan archipelago in recent three years, and the alga is Prorocentrum dentatum, which distributes in the sea areas with high salinity and (may) originates in outer sea area. Data from recent HAB rapid monitoring and ecological investigation were analyzed to study its ecological characteristics and forming inducement. The results showed that the most suitable temperature and salinity range for HAB forming was from 18 degrees C to 22 degrees C and from 21 to 31, respectively. The P. dentatum was motile and owned diurnal vertical migration bringing them the advantages in obtaining light and nutrients. Eutrophication was the preliminary condition, and water temperature, nitrate content, upwelling current, and strong competence on low phosphate environment were important to cause and maintain HAB.