珠江口南沙海域浮游植物群落结构特征

基于2015年4月(丰水期)和2015年11月(枯水期)珠江口南沙海域的调查资料,分析该海域浮游植物的种类组成、优势度、细胞丰度及多样性。共鉴定出浮游植物5门44属76种,硅藻为最主要优势种群。丰水期优势种有2种,分别为新月筒柱藻(Cylindrotheca closterium)和中肋骨条藻(Skeletonema costatum);枯水期优势种有3种,分别为萎软海链藻(Thalassiosira mala)、中肋骨条藻和有棘圆筛藻(Coscinodiscus spinosus)。丰水期和枯水期浮游植物细胞丰度分别为651.91×104个·L-1和129.21×104个·L-1,2个时期细胞丰度分布都表现为近岸向离岸递增的趋势。调查海区的浮游植物Shannon-Wiener多样性指数(H')和Pielou均匀度指数(J')的平均值在丰水期分别为1.64和0.40,而在枯水期分别为1.58和0.41,多样性总体处于较低水平。典范对应分析结果表明,丰水期影响浮游植物群落结构的主要环境因子为盐度、温度、总氮和p H,枯水期为温度、透明度、磷酸盐和盐度。

Community structure of phytoplankton in the Nansha sea area of Pearl River Estuary

We analyzed the species composition,dominant species,abundance and community diversity of phytoplankton based on the data collected from the ecological investigation of the Nansha sea area of Pearl River Estuary in both wet season (April,2015) and dry season (November,2015).A total of 76 species among 44 genera belonging to 5 phyla were identified in the survey area.Diatom was the predominant group of all the phyla.In wet season there were 2 dominant species, Cylindrotheca closterium and Skeletonema costatum.In dry season,there were 3 dominant species, Thalassiosira mala,S.costatum and Coscinodiscus spinosus.The average cell abundance of phytoplankton in wet and dry seasons was 651.91×104cells·L-1 and 129.21×104cells·L-1,respectively.The cell abundance distribution during the two seasons showed an increasing trend from inshore to offshore.In general,the Shannon-Wiener index (H′) and the Pielou evenness index (J′) were 1.64 and 0.40 in wet season,and 1.58 and 0.41 in dry season,suggesting low diversity of the phytoplankton community.Ordination diagram of CCA results indicate that salinity,temperature,DIN and pH are the main environmental factors which affect phytoplankton community in wet season,while temperature,transparency,phosphate and salinity are the main affecting factors in dry season.