2004年秋季南海北部浮游植物组成及其数量分布特征

根据2004年9月18日—10月2日南海北部航次所获得的表层浮游植物群数据, 对其组成及数量分布进行了探讨分析。该次调查鉴定浮游植物共53属152种(含变种和变型), 分别属于硅藻门35属88种、甲藻门15属60种、蓝藻门1属2种及金藻门1属1种等; 优势种中分布较广泛的有柔弱伪菱形藻Pseudo-nitzschia delicatissima、反曲原甲藻Prorocentrum sigmoides、微小原甲藻P. mininum、锥状施克里普藻Scrippsiella trochoidea和红海束毛藻Trichodesmium erythraeum等; 浮游植物细胞丰度的数量范围为(0.11—23.61)×106cells•m-3, 呈现近岸区域高于远岸区域的平面分布格局, 最大值和最小值分别出现在海南岛东北部海域的E506站和海南岛东南部海域的B3站; 浮游植物物种丰富度也是近岸的站点较高, 以靠近珠江口E708站的51种为最多。硅藻类细胞丰度范围为(0.02—8.13)×106cells•m-3, 主要分布在高盐的外海水域, 其中产二甲基磺酸丙酯(DMSP)的小环藻Cyclotella spp.在多个站点出现; 甲藻类以近岸水域居多, 细胞丰度最高达15.67×106cells•m-3(E506站), 其中数量较多的赤潮种类主要有锥状施克里普藻、反曲原甲藻、微小原甲藻、环沟藻Gyrodinium spp.等; 固氮的红海束毛藻在调查海域广泛分布, 但主要集中于东部, 以E206站最多, 高达1.8×107cells•m-3。结合水文资料和其他层次的浮游植物资料进行对比分析, 结果表明, 红海束毛藻的分布与黑潮水的入侵存在一定关系, 其分布受水团和海流的影响。

Species composition of phytoplankton and its distribution in the northern South China Sea in autumn 2004

Based on the cruise in the northern South China Sea from 18th September to 2nd October, 2004, the authors analyzed the characteristics of phytoplankton distribution and community structure in the surface layer. The results showed that there were 152 species belonging to 53 genera, including Bacillariophyta, Pyrrophyta, Cyanophyta and Chrysophyta. The wide-distributing dominant species were Pseudo-nitzschia delicatissima, Prorocentrum sigmoides, P. mininum, Scrippsiella trochoidea, Trichodesmium erythraeum and etc. Phytoplankton biomass fluctuated, from 0.11×106 to 23.61×106cells•m-3, and decreased from coastal area to far-shore area, with the maximum and minimum appearing at stations E506 and B3, respectively. The highest species numbers was 51 species at E708 close to the Pearl River estuary. The quantities of diatom ranged from 0.02×106 to 8.13×106cells•m-3 and mainly distributed in higher-salinity waters. Cyclotella spp., a kind of dimethylsulfoniopropionate (DMSP) producing species, were found at many stations. Dinoflagellate were mainly found in coastal waters with the maximum of 15.67×106cells•m-3 (at station E506), thereinto, many of them were red-tide species including Scrippsiella trochoidea, Prorocentrum sigmoides, P. mininum, Gyrodinium spp. and etc. Trichodesmium erythraeum, a nitrogen-fixation species, widely distributed in the survey waters, but mainly at the eastern waters, with the maximum biomass of 1.8×107cells•m-3 at station E206. Hydrological data and phytoplankton data in other layers had been analyzed contrastively. The results showed that the distribution of Trichodesmium erythraeum had relationship with the infall of Kuroshio current, and its distribution was affected by water mass and ocean current.