Analyses on harmful algal blooms in Zhejiang coastal waters from 2001 to 2007

The collection in red tide records in Zhejiang coastal waters was done from 2001 to 2007.Total times,area and economic loss caused by it were recorded.There are 36 red tide organisms in the bloom in Zhejiang coastal waters.Among them,20 species are diatoms,13 species dinoflagellates, remainder 3 species belong to Haptophyta,Raphidophyceae,and Protozoa respectively.In Zhejiang coastal waters,Prorocentrum donghaiense,Karenia mikimotoi and Skeletonema costatum are main red tide organisms,Karenia mikimotoi,Alexandrium tamarense and Alexandrium catenella are poisonous red tide organisms.The high frequency red tide occurrence area in Zhejiang coastal waters is in Zhoushan coast and the high red tide occurrence period is from May to Jun.The red tides in Zhejiang coastal waters were charactered by the high frequency,large-scale,long duration,wide time range,multiplicity of red tide organisms,and high frequency of poisonous blooms.