2007年春季南海西北部陆架区海域浮游植物的群落结构

摘要

据2007年春季在南海西北部陆架区海域进行的网采浮游植物调查数据,分析了浮游植物群落的结构特征.此次共鉴定出浮游植物4门318种,其中硅藻类183种,甲藻类128种,蓝藻类5种,金藻类2种.大部分海域浮游植物种类数在40～70种之间,外海区域的种类数稍高于沿岸.浮游植物密度的变化范围为0.22×104～3 683.85×104 cells/m3,平均值(标准偏差)为97.49×104(±437.38×104) cells/m3.其高值区主要位于粤西近岸海域,向外海呈递减趋势.调查海域硅藻类的平均密度(标准偏差)最高,为93.82 × 104(±434.34×104) cells/m3；甲藻类的次之,为3.65×104(±9.08×104) cells/m3.浮游植物优势种主要有拟旋链角毛藻(Chaetoceros pseudocurvisetus)、细弱海链藻(Thalassiosira subtilis)、中肋骨条藻(Skeletonema costatum)、劳氏角毛藻(Chaetoceros lorenzianus)和菱形海线藻(Thalassionema nitzschioides).该调查海域浮游植物多样性指数的变化范围为1.48 ～6.23,平均值(标准偏差)为4.70(±1.03),其分布趋势与浮游植物密度的分布趋势大致相反.将站位依等深线划分为粤西近岸海区、琼东南近岸海区和外海海区,应用非度量多维标度(nMDS)和聚类分析法分析这3个海区的浮游植物群落结构差异,并通过ANOSIM和SIMPER进行检验.结果表明3个海区之间浮游植物群落结构具有显著性差异,且粤西近岸海区与外海海区之间差异性较高.近岸种拟旋链角毛藻和中肋骨条藻在粤西近岸海区为最主要的优势种,而外海海区优势种较多,且大部分为大洋暖水性种类.%Community structure of net-phytoplankton ( ≤ 77 μim) in the northwestern South China Sea was studied based on data obtained during spring 2007. All 318 species were identified, including 183 species of diatoms, 128 dinoflagellates, 5 cyanobacteria and 2 chrysophyta. The number of species at each station ranged from 40 to 70, and was higher in the open waters than the coastal waters. Phytoplankton cell density ranged from 0. 22 x 104 to 3 683. 85 x 104 cells/m3 with an average (SD) of 97.49 × 104( ±437. 38 × 104)cells/m3, and the most abundant areas were located in the western Guangdong coastal waters. Diatoms and dinoflagellates were the dominant phytoplankton groups, with average densities (SD) of93.82xl04( ±434.34 ×104) cells/m3 and 3.65 × 104( ±9.08 × 104 ) cells/m3, respectively. The most dominant species were Chaetoceros pseudocurvisetus, Thalassiosira subtilis, Skeletonema costatum, Chaetoceros lorendanus and Thalassionema nitzschioides. The Shannon-Wiener index ranged from 1.48 to 6. 23 with an average (SD) of 4.70 ( ± 1.03) , showing that the index was higher in the open waters than the coastal waters. The stations could be divided into 3 groups, I. E. Western Guangdong coastal area, southeastern Hainan coastal area and open waters) based on isobath, and Non-metric Multidimensional Scaling (nMDS) and CLUSTER analysis were applied to find the dissimilarity among 3 groups. The results suggested that there were significant difference among these groups. The nearshore species were mainly dominated in inshore waters of western Guangdong coast and southeastern Hainan coast, while the species of open waters were mainly dominated by warm-water and oceanic species.