【摘要】 20 0 1— 2 0 0 2年的秋冬季节 ,于中国东南沿海的南澳岛周围海域突发了双环海链藻赤潮 ,该赤潮藻及其赤潮在中国都是首次记录。该赤潮藻以实心胶质块的群体形式出现 ,其群体一般呈球形或椭球形 ,常为茶褐色 ,大小不一 ,直径多数在 2— 3mm之间 ,最小的不到 0 1mm ,最大的约有 5mm。胶质块由双环海链藻和数种羽纹硅藻组成 ,前者分布于外层 ,后者包埋其中。双环海链藻的细胞密度最大达 1 75× 10 7cells/L ,占浮游植物总细胞数的 78 8%。如把包埋其中的羽纹硅藻考虑进去 ,赤潮藻胶质块的组成细胞总密度则高达 2 2 8× 10 7cells/L以上 ,占浮游植物总细胞数的 95 9%。赤潮藻的密度由湾内向外海呈显著递减趋势 ,与营养盐的平面分布格局相反。该赤潮起源于外海 ,赤潮发生机制可能与 2 0 0 1— 2 0 0 2厄尔尼诺年导致的水温异常升高有关。更多还原

【Abstract】 A bloom of colony-forming diatom of the genus Thalassiosira diporocyclus occurred in Nan’ao Island in early 2002. To our knowledge,this is the first recording of a T. diporocyclus bloom in the Southeast China Sea. The colony was solid,light brown and spherical or oval. The colony size ranged from less than 0.1mm to 5mm. The majority were around 2—3mm. In the outer layers,the colony was mainly composed of T. diporocyclus ,while some pennate diatoms were embedded in the center. The highest cell density of T. diporocyclus alone was 1.75×10 7cells/L,accounting for 78.8% of total phytoplankton. This increased to 2.28×10 7cells/L (95.9%) when pennate diatoms inside the colony were included. Results indicate that the abundance and cell density of T. diporocyclus increased from the inner bay to the open waters during the bloom and reversely correlated with the distribution trend of the abundant nutrients. The bloom originated in open waters,and its occurrence is probably related to abnormally high water temperatures resulting from the 2001—2002 El Nio event.更多还原