2013年夏季曹妃甸邻近海域浮游植物群落的空间格局及其影响因素

Spatial pattern of phytoplankton community and influential factors in Caofeidian coastal waters in summer of 2013

为阐明曹妃甸邻近海域浮游植物群落的水平和垂直分布特征,于2013年8月在该海域开展调查航次,应用Utermöhl方法研究了浮游植物的物种组成、细胞密度和优势种等特征,采用冗余分析(RDA)和聚类分析探讨了浮游植物群落的空间分布特征及其与环境因子的关系。结果表明,本次调查共鉴定得到浮游植物3门34属66种,主要由硅藻和甲藻组成,浮游植物密度范围为(0.85~39.07)×104 cells/L,主要优势种为长菱形藻(Nitzschia longissima)、中肋骨条藻(Skeletonema costatum)和浮动弯角藻(Eucampia zodiacus)等。浮游植物密度的空间分布与温度、盐度和营养盐等环境因子密切相关。水平方向上,近岸海域的细胞密度通常高于远岸海域,主要与陆源营养盐输入有关。垂直方向上,浮游植物群落的变化主要出现在水深超过20 m的远岸海域,细胞密度随深度增加而降低,大部分硅藻和甲藻主要分布在表层水体,而具槽帕拉藻(Paralia sulcata)等底栖种类主要分布在中层和底层水体,这些主要与海水的垂直混合受到抑制有关。

In order to clarify the horizontal and vertical distributions of phytoplankton community and influential factors in Caofeidian coastal waters,an investigation was conducted in August 2013.The species composition,cell density and dominant species were analyzed.The redundancy analysis(RDA)and clustering analysis were used to study the spatial variations of phytoplankton community and their relationships with environmental factors.The results showed that a total of 66 species in 34 genera of 3 phyla were identified.Bacillariophyta and Pyrrophyta were the dominant groups.The phytoplankton densities were(0.85~39.07)×104 cells/L and dominant species included Nitzschia longissima,Skeletonema costatum,Eucampia zodiacus,etc.The seawater temperature,salinity and nutrients were important factors affecting phytoplankton distributions.Horizontally,cell densities showed relatively high in the inshore waters than the offshore waters,mainly caused by terrestrial nutrient inputs.Vertically,the spatial variations of phytoplankton community were observed in the offshore waters with depth exceeded 20 m.It was found that cell densities decreased with depth and most diatoms and dinoflagellates distributed in the surface waters,and benthic diatoms(e.g.,Paralia sulcata)mainly distributed in the middle and bottom waters.The weakened seawater vertical mixing due to stratification was an important factor controlling the phytoplankton distributions.