夏季北部湾的浮游植物群落

SUMMER PHYTOPLANKTON COMMUNITY IN THE BEIBU GULF

根据2009年8月份对北部湾(18°N^22°N,107°E^110°E)海域12个采水站位的调查,分析夏季调查区浮游植物的群落结构特征。通过Uterm hl方法共鉴定出浮游植物4门60属90种(不包括未定种),群落组成以硅藻为主,其次是甲藻。浮游植物生态类群以广温广布型种为主,调查区的优势种为菱形海线藻(Thalassionema nitzschioides)、柔弱角毛藻(Chaetoceros curvesitus)、尖刺伪菱形藻(Pseudo-nitzschia pungens)和萎软几内亚藻(Guinardia flaccida),此外蓝藻门的铁氏束毛藻(Trichodesmiumthiebaultii)也作为优势种出现。调查区细胞丰度介于0.330~19.765×103/L,平均为4.677×103/L。调查区表层浮游植物丰度由近岸区向湾中部逐渐降低,而且甲藻在调查区的近岸站位出现高值。调查区浮游植物丰度在垂直方向随着水深的增加而递减。Shan-non-Wiener多样性指数和Pielou均匀度指数在调查区的近岸站位出现低值区,群落结构稳定性较差。

Phytoplankton samples were taken from the Beibu Gulf（18°N^22°N,107°E^110°E） in August,2009.The phytoplankton species composition,community structure,and its spatial distribution were reported.A total of 4 phyla 60 genera and 90 taxa were identified according the Uterm hl method in the survey area.The major groups were diatom and dinoflagellate.Most of the phytoplankton ecotype was temperate coastal species,while the warm-water species and oceanic species were rarely presented.The dominant species in the survey area were Thalassionema nitzschioides,Chaetoceros sp.,Pseudo-nitzschia pungens,Guinardia flaccida,and Trichodesmium thiebaultii.The cell abundance of phytoplankton ranged from 0.330 to 19.765×103cell/L,with an average of 4.677×103 cell/L.The phytoplankton cell abundance reduced from coastal area to the center.Vertically,the phytoplankton cell abundances were concentrated in surface water and decreased rapidly down to the bottom.The Shannon-Wiener index and Pielou＇s evenness index were low in the coastal area of the survey area,which indicated the community structure of phytoplankton was unstable.