EVOLUTION AND FORMATION CAUSES OF ALEXANDRIUM TAMARENSE RED TIDE IN THE SEA AREA OF THE NANHUANGCHENG ISLAND

In September 2006,the red tide in the sea area of the Nanhuangcheng island was investigated,which was the first record of red tide caused by Alexandrium tamarense in Yantai.The area of the red tide was about 2.37 square kilometers,and the highest cell abundance of Alexandrium tamarense reached 2.334 108 cells/L.Because declines of the large number of red tide organism consumed dissolved oxygen in water,oxygen in lower water lacked seriously,leading all the fishes of cage culture to death.Nearly half of the Haliotis discus cultured on the shore were caused to die by Paralytic Shellfish Poisoning(PSP) secreted by Alexandrium tamarense.The main cause of red tide was that ballast water discharge brought about red tide organism.Large number of organic matters of land-based sources,nutrient salt ejected into the sea and self-pollution of mass culture's of Shellfish raft provided rich material basis for outbreak of proliferation of red tide organism.And the hydrometeorological conditions provided a good physical environment for the occurrence of the red tide.