Seasonal investigations on phytoplankton community and environmental factors were carried oat in Zhanjiang Bay of Guangdong, China, in February (winter), May (spring), August (summer) and November (autumn) of 2009. The total 311 species in 97 genera (including varieties and forms) were found out in this sea area: 178 species occurred in spring, 142 in summer, 117 in autumn, and 92 in winter. Taxonomically, 209 species in 54 genera were Bacillariophyta, accounting for 67.2 % of all species; 71 species in 20 genera were Pyrrophyta, accounting for 22.8 %; 14 species in 9 genera were Cyanophyta, accounting for 4.5 %; 11 species in 9 genera were Chlorophyta, accounting for 3.5 % ; 2 species in 2 genera were Chrysophyta, accounting for 0.6 % ; 2 species in 1 genus were Euglenophyta, accounting for 0.6 % ; 1 species in 1 genus was Gryptophyta, accounting for 0.3 % and 1 species in 1 genus was Raphidophyceae, accounting for 0.3 %. 19 dominant species were scrutinized, of which 7 were in winter, 4 in spring, 7 in summer and 7 in autumn. All the dominant species belong to Bacillariophyta. The majority of dominant species were Skeletonema costatum, Chaetoceros curvlsetu, Asterionellopsis glacialis, Eucampia zoodiacus, Leptocylingdrus danicus and Nitzschia paradoxa. No dominant species was widespread in all seasons. All the dominant species had eurythermic and euryhaline characteristics of subtropical community structure along the seashore. 33 species occurred in all seasons, and 34-69 species in two seasons. The Jaccard similarity coefficient ranged 0.17-0.31, implying obvious seasonal succession. The average diversity index and evenness were 3.02 and 0.43, respectively, indicating the lasting community composition in this sea area. The average cell abundance of phytoplankton ranged from 13.60xl04 to 67.33 xlO4 cells/L, with the maximum in summer, the second abundance in spring and the minimum in winter. The scenario was particular since phytoplankton in other sub-tropical areas often bloomed in spring or autumn. The abundance of phytoplankton was significantly correlative to the chlorophyll a and the water temperature, and coefficient correlation was 0.633 and 0.418 (p<0.01, n=112, 2-tailed), respectively. It was negatively related to the DIN and silicate, and coefficient correlations were -0.493 and 0.378 (p<0.01, n-112, 2-tailed) , respectively. No correlation to the other factors was found.%2009年2月-11月对广东省湛江湾的浮游植物进行了周年的季节调查,结果共检出浮游植物97属311种(包括变种和变型):春季178种、夏季142种、秋季117种、冬季92种,其中硅藻门54属209种,占总种类数的67.2％；甲藻门20属71种,占总种类数的22.8％；蓝藻门9属14种,占总种类数的4.5％；绿藻门9属11种,占总种类数的3.5％；金藻门2属2种,占总种类数的0.6％；裸藻门1属2种,占总种类数的0.6％；隐藻门1属1种,占总种类数的0.3％；针胞藻纲1属1种,占总种类数的0.3％.优势种共有19种:冬季7种、春季4种、夏季7种、秋季7种,全为硅藻,主要优势种为中肋骨条藻Skeletonema costatum、旋链角毛藻Chaetoceros curvisetus、冰河拟星杆藻Asterionellopsis glacialis、浮动弯角藻Eucampia zoodiacus、丹麦细柱藻Leptocylingdrus danicus和奇异菱形藻Nitzschia paradoxa等,没有全年广布优势种,群落结构具有亚热带和沿岸性特征；4季均出现的种类共有33种,各季节间共有种类数在34～69种,Jaccard种类相似性指数范围在0.17～0.31,季节更替明显.多样性指数和均匀度平均值分别为3.02和0.43,群落结构较稳定；浮游植物细胞丰度在13.60×104-67.33×104 cells/L之间,夏季最高,春季次之,冬季最低,属季节单峰型变化,与一般亚热带春、秋季出现丰度高峰不一致.浮游植物细胞丰度与叶绿素a和水温呈极显著的正相关,相关系数分别为0.633和0.418 (P＜0.01,n＝112,双尾),与无机氮和活性硅酸盐呈极显著的负相关,相关系数分别为-0.493和-0.378 (P＜0.01,n＝112,双尾),与其他环境因子不存在明显的相关性.
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