2004年秋季长江口海域浮游植物的群落结构和多样性

Community structure and diversity of phytoplankton in the estuary of Yangtse River in Autumn

2004年9月20日～10月9日对长江口海域浮游植物的种类组成、多样性、丰度及其分布进行了调查研究。本次调查，长江口海域共鉴定浮游植物2门26属68种（含4个变种、6个不确定种），主要为温带近岸性种，其中硅藻门有21属51种，占总种数75％，甲藻门有5属17种，占总种数的25％。硅藻门中角毛藻属（Chaetoceros）和圆筛藻属（Coscinodiscus）的种类最多，分别为17种（占硅藻总种数的33．33％）和7种（占硅藻总种数的13．73％），甲藻门中以角藻属（Ceratium）为主，有10种，占甲藻总种数的58．8％。浮游植物数量平均为1400．00×10^4cells／m^3。硅藻的平均数量为1392．69×10^4cells／m^3，占浮游植物总量的99．3％；甲藻的平均细胞数量为7．31×10^4cells／m^3，占浮游植物总量的0．7％。多样性指数平均值为1．90，而均匀度指数平均值为0．68。浮游植物密集区出现在调查区域的中部，靠近长江入海口水域。浮游植物的优势种主要为：中肋骨条藻（Skeletonema costatum（Greville）Cleve）、尖刺菱形藻（Nitzschia pungens Grunow）、菱形海线藻（Thalassionema nitzschioides Grunow）、洛氏角毛藻（Chaetoceros lorenzianus Grunow）、柔弱角毛藻（Chaetocerosde—bilis Cleve）、窄隙角毛藻（Chaetoserosa afinis Lauder）和旋链角毛藻（Chaetoecros curvisetus Cleve）。本次调查长江口海域的浮游植物可划分为：东北部组群、近河口组群和南部组群3个主要生态类型。

Investigation was conducted on the species composition, diversity, abundance and distribution of phytoplankton in the estuary of Yangtse River during Sep. 20-Oct. 7, 2004. The results showed that 68 phytoplankton species were identified altogether, belonging to 2 phyla with 26 genera, in which 75% were Bacillariophyceae（21 genera and 51 species） and 25% were Phrrhophyta（5 genera and 17 species）. In Bacillariophyceae, Chaetoceros and Coscinodiscus were the dominant groups in species, they possessing 17 species （accounting for 33.3 %） and 7species （accounting for 13.7 %）, respectively. In Phrrhophyta, Ceratium had 10 species, being absolutely dominant. The average quantity of phytoplankton was 1 400×10^4 cells/m^3, Bacillariophyta and Phrrhophyta occupying 99. 3 % （1 392. 69× 10^4 cells/m^3） and 0.7 %（7. 31× 10^4 cells/m^3）, respectively. In addition, the average diversity index （H＇） and evenness（J） values were 1.90 and 0.68, respectively. It was also found that the dense area of phytoplankton was close to the mouth of Yangtse River during the survey period. The dominant species included Skeletonema costaturn （Greville） Cleve, Nitzschia pungens Grunow, Thalassionema nitzschioides Grunow, Chaetoceros lorenzianus Grunow, Chaetoceros debilis Cleve, Chaetoseros a f finis Lauder, and Chaetoecros curvisetus Cleve.