To provide basic data for sustainable management of the coastal ecosystem,the community structure of phytoplankton and the associated environmental factors were investigated in the coastal waters of Leizhou Bay of Guangdong from February to November in 2013.There were totally 142 species recorded,with 1 16 species in 42 genera of Bacillariophyta,accounting for 81.3% of the community,and 19 species in 10 genera of Pyrrophyta,ac-counting for 13.8% of the community,5 species in 5 genera of Cyanophyta,accounting for 3.5%,and other 2 spe-cies only accounting for 1.4%.Most of dominant species were low saline species characterized of a sub-tropical and nearshore community except for a few open sea species.There were neither obvious seasonal dominant species nor annual wide spread dominant species.The average abundance of phytoplankton was 12.92 ×104 cell/dm3 ranged from 0.26 ×104 to 60.35 ×104 cell/dm3 ,with the highest density in autumn,followed by winter,summer and spring in consequence.In addition,the greatest abundance of species was observed in the central area and lower abun-dances were in the top and the mouth of Leizhou Bay.The abundance of phytoplankton was correlated negatively to the water temperature with a coefficient of-0.415 (p<0.05,n=36,two-tailed t test)and no significant correla-tions (p>0.05 )founded with other environmental factors.The community structure of phytoplankton in the coastal waters of Leizhou Bay changed substantially compared with that of 1987 as species numbers and dominant species increased by 61.4%and 100%,respectively,besides a 30 times of abundance increment,which indicates a healthy and stable community by its complexity.%2013年2月至11月对雷州湾海域的浮游植物和环境因子进行调查，并对该海域浮游植物的群落结构特征及其影响因素进行分析．结果表明，雷州半岛海域浮游植物共有142种，其中硅藻门42属116种，占总种类数的81.3％；甲藻门10属19种，占总种类数的13.8％；蓝藻门5属5种，占总种类数的3.5％；其他门类2属2种，占浮游植物种类数的1.4％．群落结构以低盐沿岸性种类为主，并夹杂有少数外海种类，具有亚热带和沿岸性特征，各季节优势种的优势度并不十分明显，没有全年广布优势种．浮游植物细胞丰度的变化范围为0.26×104～60.35×104 cells／dm3，平均丰度为12.92×104 cells／dm3，呈现秋季＞冬季＞夏季＞春季，以及海湾中部大于湾顶和湾口的时空分布格局．细胞丰度与温度呈现显著的负相关，相关系数为－0.415（p＜0.05，n＝36，双尾），与其他主要生态因子不存在明显的相关性．浮游植物群落的演替发生了较大的变化，种类数较1987年增加了61.4％，优势种类数增加了1倍，丰度增加了约30倍，但群落结构复杂而稳定，是健康的生态群落．
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