深圳湾浮游植物的季节变化

2008年2月至11月对深圳湾的浮游植物和理化环境因子进行了4个季度月的调查,结果共检出浮游植物150种（包括变种和变型）：春季66种、夏季72种、秋季54种、冬季50种,其中硅藻门36属108种,甲藻门14属36种,绿藻门3属3种,蓝藻门2属3种。优势种共有湖沼圆筛藻Coscinodiscus lacustris、中肋骨条藻Skeletonema costatum、夜光藻Noctiluca scientillans 3种：春季1种、夏季1种、秋季1种、冬季2种,优势种群由春夏季的湖沼圆筛藻演替至秋季的中肋骨条藻、冬季的中肋骨条藻和夜光藻,没有全年广布优势种;4季均出现的种类共有9种,其中硅藻8种,甲藻1种,各季节间共有种类数在13～31种,Jaccard种类相似性指数范围在0.12~0.35,季节更替明显。多样性指数和均匀度的变化范围分别为0.006~1.724和0.001~0.306,群落结构较脆弱。细胞密度在1.25×107~217.90×107 cells.m-3,夏季最高,春季次之,冬季最低,属季节单峰型变化,与一般亚热带春、秋季出现密度高峰不一致,这与深圳湾陆源营养物质的扰动有关,其无机氮和活性磷酸盐含量均劣于国家海水水质标准的四类水,因此,该海域水质营养类型属于亚热带富营养型。细胞密度与硅酸盐呈极显著的负相关,相关系数为-0.446（p〈0.01,n=36,双尾）,与水温呈显著的正相关,相关系数为0.371（p〈0.05,n=36,双尾）,与其他因子的相关性不明显。从优势种的种类数和多样性指数分析,深圳湾浮游植物的群落结构已趋于单一化,生态系统抗干扰能力极为脆弱。

Seasonal changes of the phytoplankton in Shenzhen Bay

From February to November 2008,seasonal investigation for phytoplankton community was carried out in Shenzhen Bay of Guangdong province,China.Among all 150 species founded in the bay,66 occurred in spring,72 in summer,54 in autumn,and 50 in winter.Therein,108 species in 36 genera belonged to Bacillariophyta,36 species 14 genera Pyrrophyta,3 species 3 genus Chlorophyta and 3 species 2 genera Cyanophyta.3 dominant species were scrutinized,of which 1 species in spring,1 in summer,1 in autumn and 2 in winter.The dominant species were mainly Coscinodiscus lacustris,Skeletonema costatum and Noctiluca scientillans.The succession of dominant species was from Coscinodiscus lacustris of spring-summer to Skeletonema costatum of autumn,Skeletonema costatum and Noctiluca scientillans of winter finally.No dominant species was spread widely in all seasons,while 8 Bacillariophyta and 1 Pyrrophyta species occurred in all seasons,and 13~31 common species in two seasons.The obvious seasonal succession was found based on the Jaccard index with a range from 0.12 to 0.35.The diversity index changed from 0.006 to 1.724,and the evenness indices from 0.001 to 0.306,which indicating the community composition was rather brittle in this area.The density of phytoplankton ranged from 1.25×107 cells·m-3 to 217.90×107 cells·m-3 with a descending order from summer to spring,autumn,and winter.The result was particular as phytoplankton often bloomed in spring or autumn in other sub-tropic areas,and its main reason was due to the perturbation of onshore nutrient.The concentrations of the DIN and phosphate were worse than the Ⅳ limit value of the Sea Water Quality Standard of China.Therefore,the water quality was of the subtropical eutrophic type.The density of phytoplankton was significantly negative related to the silicate,and the coefficient correlation was-0.446（p0.01,n=36,2-tailed）.Meanwhile,The density of phytoplankton was correlative to the water temperature with the coefficient correlation of 0.371（p0.05,n=36,2-tailed）.No obvious correlation was found with other factors.In terms of the dominant species and diversity index,the community composition of the phytoplankton had tended to the simplification,and the tamper-resistant capability was rather fragile in the ecological system in Shenzhen Bay.