OUTBREAK OF CHATTONELLA MARINA RED TIDE AND ITS RELATIONS TO ECOLOGICAL PARAMETERS IN DAPENG BAY, SOUTH CHINA SEA
Qi Yuzao; Hong Ying; Lu Songhui; Chu Jianhua;Zhang Jiaping ;Zhu Congju; Li Yaqin(Institute of Hydrobiology, Jinan University, Guongzhou 510632)Liang Song; Li Jinrong(South China Sea Branch, SOA, Guangzhou 510300)
A Chattonella marina Hara et Chihara red tide occurred in March 20-21, 1991in Dapeng Bay, South China Sea. Its Maximum cell density reached 1.4 × 107 cells/L. A dynamic fuzzy cluster dendrogram of samples based on eight ecological parameters (temperature, salinity, iron, atmospheric pressure, wind velocity, phosphate,nitrate and ammonia) was used to analyse the variation of environmental factors measured before, during and after the red tide outbreak. The relationship between thered tide and environmental factors is discussed. The research showed that concentration of nitrate, phosphate, ammonium and iron increased just before the red tide outbreak, and that temperature and salinity were ca. 20℃ and 31.38S respectively atthe start of the red tide outbreak. Deletion of wind velocity and iron changed thecluster dendrogram obviously. It is concluded that: when temperature and salinitywere optimum, iron and wind velocity were the decisive factors for the initiation ofred tide. The increase of macronutrients, specifilly nitrate, also played a principalrole in this red tide.