夏季长江口海域浮游植物营养限制的现场研究

2001年7月23日到8月15日期间在长江口及邻近海域进行了浮游植物限制因子测定的现场培养实验研究。研究结果显示:在冲淡水域磷为浮游植物生长的显著潜在限制因子,离岸较远的远河日海域氮是潜在限制因子,中间海域是磷、氮潜在限制过渡区。在调查海域范围内硅和铁不是潜在限制因子。如果水体中存在对浮游植物的某种限制因子,浮游植物的生长将明显受到限制,一旦消除这种限制因子,浮游植物就会快速生长。发生夜光藻(Noctiluca scintiuans)赤潮时,受捕食压力的影响,海水中浮游植物的现存量很低,一旦捕食压力被解除,有充足的营养条件下,浮游植物会快速繁殖。

Study on nutrient limitation of phytoplankton in field experiment of Changjiang Estuary in summer

From July 23rd to August 15th, 2001 , a cruise and a field experiment oi cultivation to determine the limitation factors of phytoplankton were carried out in the Changjiang Estuary and adjacent areas. The results of the research showed that phosphate was the obvious potential limiting nutrient in the diluted area; DIN in the offshore of the Changjiang Estuary and the phosphate and DIN in the middle area. Iron and silicate were not the potential limiting factors. If there were some kinds of limiting factors in water column, the growth of phytoplankton would be limited obviously. In case of disapperance of the limiting factor, the phytoplankton would grow fast. When the blooming of Noctiluca scintiuans was taking place, because of the grazing pressure, the biomass of phytoplankton changes into low in a short time. When the grazing pressure disappeared, the phytoplankton will grow quickly in abundant nutrient condition.