Sun Jun, Tian Wei
Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, Shandong, China.
Ying Yong Sheng Tai Xue Bao. 2011 Jan;22(1):235-42.
Based on the multidisciplinary cruise investigation in the Yangtze River estuary and its adjacent waters in April 2009, the phytoplankton species and their abundance were analyzed by the Utermöhl method, and the size-fractionated chlorophyll a concentrations were determined. In the meantime, the relationships between the dominant phytoplankton species and environmental physicochemical factors were explored by Canonical Correspondence Analysis (CCA). A total of 3 phyla, 46 genera, and 64 species (not including uncertain species) were found, mostly diatoms and dinoflagellates, with diatoms dominant. Most of these species were temperate and coastal, but a few brackish and oceanic species also presented. There were 33 diatom genera including 45 species. The dominant species were Skeletonema dohrnii, Paralia sulcata, Thalassionema nitzschioides, Pseudo-nitzschia pungens, Melosira granulata var. angustissima, Pseudo-nitzschia delicatissima, and Guinardia delicatula. The phytoplankton cell abundance ranged from 0.3 to 13447.7 cells x ml(-1), with an average of 1142.385 cells x ml(-1). Concerning the horizontal distribution, cell abundance was the highest in the middle-northern part of the survey area, with S. dohrnii dominant. The phytoplankton cell abundance was high in the surface layer water, and decreased with increasing depth. The Shannon diversity index and Pielou evenness index were consistently low in the middle-northern part of the survey area, in contrast to the trend of phytoplankton cell abundance. The chlorophyll a concentrations ranged from 0.34 to 29 g x L(-1), with an average of 3.3 g x L(-1), consistent with the cell abundance distribution. Size-fractionated chlorophyll a results showed that the biomass in the middle-northern part of the survey area was mainly composed of microphytoplankton (> 20 microm), while that in offshore waters was mainly composed of nanophytoplankton (2-20 microm) and picophytoplankton (< 2 microm). The CCA showed that the distribution of predominant species S. dohrnii was mainly affected by the water nitrate content, pH value, and microzooplankton grazing. On the contrary, the distribution of other common species including dinoflagellates was mainly associated with water salinity, and phosphate and silicate contents. The paper also compared the differences in the methods of phytoplankton quantification used by the present study and by the previous studies based on net samples. It was suggested that in future work, the autecological study of genus Skeletonema in the Yangtze River estuary and its adjacent waters should be strengthened.
基于2009年4月在长江河口及其邻近海域开展的多学科巡航调查，采用Utermöhl方法分析了浮游植物种类及其丰度，并测定了不同粒径分级的叶绿素a浓度。同时，通过典范对应分析（CCA）探讨了优势浮游植物种类与环境理化因子之间的关系。共发现3个门、46个属、64种（不包括不确定种类），主要为硅藻和甲藻，其中硅藻占优势。这些种类大多为温带和沿岸种类，但也出现了少数咸淡水和大洋种类。有硅藻33属，共45种。优势种为柔弱伪菱形藻、槽纹藻、菱形海线藻、尖刺伪菱形藻细窄变种、颗粒直链藻极狭变种、柔弱伪菱形藻和优美几内亚藻。浮游植物细胞丰度范围为0.3至13447.7个细胞·ml⁻¹，平均为1142.385个细胞·ml⁻¹。在水平分布上，调查区域中北部的细胞丰度最高，以柔弱伪菱形藻占优势。浮游植物细胞丰度在表层水中较高，并随深度增加而降低。调查区域中北部的香农多样性指数和皮洛均匀度指数一直较低，与浮游植物细胞丰度的趋势相反。叶绿素a浓度范围为0.34至29 μg·L⁻¹，平均为3.3 μg·L⁻¹，与细胞丰度分布一致。不同粒径分级的叶绿素a结果表明，调查区域中北部的生物量主要由微型浮游植物（> 20 μm）组成，而近海水域的生物量主要由小型浮游植物（2 - 20 μm）和微微型浮游植物（< 2 μm）组成。CCA分析表明，优势种柔弱伪菱形藻的分布主要受水体硝酸盐含量、pH值和微型浮游动物摄食的影响。相反，包括甲藻在内的其他常见种类的分布主要与水体盐度、磷酸盐和硅酸盐含量有关。本文还比较了本研究与以往基于网采样本的研究中浮游植物定量方法的差异。建议在今后的工作中，加强长江河口及其邻近海域伪菱形藻属的个体生态学研究。
