大亚湾春季卡盾藻种群动态及其赤潮成因分析

研究了2000年春季大亚湾古老卡盾藻/海洋卡盾藻(Chattonella antique/marina)种群动态及其与环境因子的关系。卡盾藻是一种沿岸分布的有害赤潮针孢藻,2000年春在大亚湾海域高密度高频率出现,最高细胞密度为129cells/mL。大亚湾合适的水温、盐度及丰富的营养盐含量为卡盾藻的生长提供了良好的环境条件,而较低的Si∶N及持续的阴雨天气抑制了小型硅藻的生长,使卡盾藻在浮游植物种群竞争中占据一定地位。孢囊萌发被认为是水体中卡盾藻营养细胞及其赤潮发生的种源,但孢囊需经过4个月以上、11℃以下低温处理后方可成熟和萌发,大亚湾冬季水温,不能满足卡盾藻孢囊休眠成熟的需要。作者推测,2000年春大亚湾高密度卡盾藻营养细胞的种源可能来源于由船舶压舱水所带来的成熟孢囊。  

Population dynamics of Chattonella in spring in Daya Bay, the South China Sea and the cause of its blooms

Six stations were set in cultural area of Daya Bay, the South China Sea, and water samples were collected every day from St.1 and St.2 and every three days from St.3-St.6 between April 7 and May 23 2000.Physical parameters (water temperature, salinity), chemical parameters such as dissolved nitrogen ( DIN, NO3- N+ NO2- N+ NH4- N), dissolved phosphorus (DIP, orthophosphates), dissolved silicate ( DSi), COD, meteorologic parameters, and biological parameters of chlorophyll a (Chl a), phytoplankton cell density and composition were measured.Population change of Chattonella antique /marina and its relationships with environmental factors and other groups of phytoplankton such as diatoms and dinoflagellates, were studied in this paper.The causative mechanism for the high occurrence of Chattonella was discussed as well.Generally, Chattonella has low capability in phytoplankton competition due to its low reproduce rate.However, Chattonella occurred in Daya Bay frequently in high densities in the spring of 2000, which the maximum cell density was 129 cells/mL.The appropriate water temperature, salinity and abundant nutrient contents in Daya Bay provided a suitable condition for the growth of Chattonella.On the other hand, low values of SiBN and continuous overcast and rainy weather in 2000 spring inhibited the growth of micro-diatoms, therefore, benefited the high propagation of Chattonella.Cyst has been regarded as the seed bed of motile cells in the water column of Chattonella and its blooms.However, it is necessary requirement for cyst to get through at least four months of compulsive resting stage under the temperatures below 11 e for maturation.The high winter water temperatures of Daya Bay can not provide the appropriate condition for Chattonella cysts to maturate.From the results, it could be suggested that high concentrations of motile cells of Chattonella in the spring of 2000, together with Chattonella blooms occurred in Daya Bay and other nearby sea areas, might result from the germination of mature cysts brought by the ballast waters.