【摘要】 根据2004年2月、5月、8月、11月长江口生态环境调查资料,分析了长江口及邻近海域浮游植物群落结构的时空变化特征及其与环境因子的关系。结果表明,2004年,共鉴定浮游植物153种,其中硅藻类111种,甲藻类42种。与20世纪80年代同期相比,春季硅藻种类数目显著增加,夏季减少,秋冬两季变化不大,甲藻种类数目在春、夏、秋季均有明显增加。2004年浮游植物种类以温带近岸性种类为主,暖水性和广布性种类和丰度增加;除冬季以外,中肋骨条藻在长江河口及邻近海域仍处于绝对优势。受长江巨大径流影响,2004年浮游植物丰度季节变化是单周期型,高峰期出现在春季,与以往调查结果不同。通过CCA梯度分析,将长江口浮游植物分为六大类群,不同浮游植物类群对环境因子的响应机制不同。2004年影响长江口浮游植物群落结构的主要环境因素为温度、盐度、透明度、溶解氧、总磷、pH、氨氮和磷酸盐(P<0.01);与80年代相比,长江口生态与环境发生了显著改变:硅酸盐、硝酸盐和亚硝酸盐增加1倍余,氨氮和溶解氧含量降低,冬季、春季和秋季的水温显著上升。环境因子的改变直接影响长江口浮游植物的群落结构,各季节要引起长江口浮游植物群落结构变异的驱动因素不同。更多还原

【Abstract】 Data obtained in the Changjiang estuary and its adjacent waters during February, May, August, November in 2004 were analyzed for understanding the seasonal succession patterns of phytoplankton, and the relationship between the community structures and environmental factors. A total of 153 species were identified, among which 111 were diatom and 42 dinophytes. Compared with the data of 1985—1986, the abundance of dinophytes increased in spring, declined in summer, and slightly changed in fall and winter. The number of dinophytes species increased in spring, summer and fall. In 2004, the phytoplankton community was mainly comprised by temperate coastal species; tropic and widespread species appear more in frequency and abundance; Skeletonema costatum dominated in the estuary. The variation in phytoplankton abundance in 2004 stood out in spring with a single peak, different from 1985—1986. The diversity index of phytoplankton community in spring was slightly greater than that of 1986. Six assemblages of phytoplankton taxa were confined accord- ing to CCA ordination analysis, and were in possession of different responding styles to the environmental variables. In 2004, temperature, salinity, transparency, DO, TP, pH, NH+4 and PO ^3-4 were the main factors affecting the structure of phytoplankton community （P<0.01）. Since 1980’s, the environmental conditions had changed obviously: concentrations of SiO （²）₃ , NO-3 and NO-2 nearly doubled that of 1985—1986, while NH4+ and DO decreased; and the temperature rose significantly. As a result, the structure of phytoplankton community changed too, and the factors driving the community variation were diverse during all seasons.更多还原