长江口北支浮游植物群落结构周年变化特征

2010年10月至2011年9月对长江口北支水域的浮游植物进行周年调查,共采集到183种（包括变种和变型）,隶属于7门60属,其中硅藻门种类最多,有35属137种,占浮游植物总种类数的75%。周年优势种为具槽直链藻、中肋骨条藻、条纹小环藻、两栖颤藻、小伪菱形藻双楔变种、颗粒直链藻和小环藻未定种。本次调查中,季节间浮游植物的丰度差异不显著（P〉0.05）,但各月间浮游植物丰度差异显著（P〈0.05）,全年丰度在2.83×10^3～6.18×10^4cells/L之间,其中6月的丰度最高,1月的丰度最低,全年的平均丰度为1.73×10^4cells/L。Pearson相关性分析显示,浮游植物丰度与硝酸盐浓度显著正相关（P〈0.05）,与氨氮浓度极显著正相关（P〈0.01）,含氮营养盐对浮游植物的影响明显。

Annual variation of phytoplankton community in the north branch of the Yangtze River estuary

An annual survey was conducted on the community structure of phytoplankton from October 2010 to September 2011 at 5 stations in the north branch of the Yangtze River estuary. A total of 183 phytoplankton species were identified,which belonged to 60 genera of 7 phyla. Diatom was the major phytoplankton group which was 137 species of 35 genera and its species number accounted for75% of all species. Melosira sulcata,Skeletonema costatum,Cyclotella striata,Oscillatoria amphibia,Pseudo-Nitzschia sicula v. Bicuneata,Cyclotella sp. and Melosira granulata were the dominant species. Phytoplankton abundance difference was not significant among seasons（ p〉0. 05）,but monthly difference was significant（ p〈 0. 05）. Phytoplankton density ranged from 2. 83 × 10^3 to 6. 18 × 10^4 cells /L with the nighest density in June and the lowest density in January. The annual average abundance was 1. 73 10^4 cells /L. Correlation analysis found that the density of phytoplankton was significantly positively correlated to nitrate and ammonia. The impact of nitrogenous nutrients for phytoplankton was significantly.