【摘要】 利用2008年4月(春季)和8月(夏季)在杭州湾生态监测区调查海域获得的浮游植物样本,分析了浮游植物的种类组成、优势度、丰度及多样性、均匀度的变化趋势,并将分析结果与该海域2005~2007年春、夏季的浮游植物各数据资料进行了对比,结果表明,2008年春、夏季调查区鉴定出的浮游植物数量达61种,隶属于5个门29属,以硅藻门为最多,有21属49种;其次是甲藻门,4属7种;蓝藻门,2属2种;绿藻门,1属2种;金藻门,1属1种。中肋骨条藻Skeletonema costatum和琼氏圆筛藻Coscinodiscus jonesianus为调查区主要的浮游植物优势种。以S13和S36站位的连线为界,将调查海域划分为南、北两个观测区,2008年春季,南观测区内的浮游植物丰度高于北观测区,夏季情况则恰好相反,表明浮游植物的丰度分布受季节变化影响。该海域中浮游植物的多样性指数(H′)和均匀度指数(J′)均偏低,2008年4月和8月的多样性指数平均值分别为1.31和1.58,均匀度指数平均值分别为0.324和0.413。2005~2008年春、夏季,该海域浮游植物群落组成不稳定,单优藻类优势度呈明显上升趋势,生物多样性呈现下降趋势,生态风险有加大趋势。更多还原

【Abstract】 Hangzhouwan Bay is a typical strong-tide bay in bell-mouth shape located to the northeast of Zhejiang Province,south of Shanghai and west of the East China Sea.It is also an ecological barrier in guarding against and mitigating marine disasters.Phytoplankton is the base of marine ecosystem.The study of its distribution,biodiversity and variation trend is of great importance for the assessment of ecosystem health and maintenance of the ecological safety and sustainable development of the ecosystem in Hangzhouwan Bay.On the basis of the data of phytoplankton collected in this ecology-monitoring area in April and August,2008,combined with the data from 2005 to 2007,the species composition,abundance distribution,diversity and their inter-annual variation are analyzed.The results showed that of the 61 identified species of phytoplankton that belong to 29 genera of 5 phyla,Bacillariophyta was the richest with 49 species from 21 genera,accounting for 80.3 % of the total species number,and the next was Pyrrophyta with 7 species from 4 genera accounting for 11.5 %;Cyanophyta 2 species from 2 genera accounting for 3.3 %;Chlorophyta 2 species from 1 genus accounting for 3.3 % and Chrysophyta 1 species from 1 genus accounting for 1.6 %.The dominant species of the phytoplankton in April were Skeletonema costatum,Coscinodiscus jonesianus,Biddulphia sinensis,Coscinodiscus oculus-iridis and Nitzschia lorenziana.But in August they were S.costatum,C.jonesianus,and Chaetoceros abnormis.S.costatum and C.jonesianus were not only the dominant species of phytoplankton in this area,but also the dominant species in the bays along the coastal areas of the Yellow Sea and the East China Sea.If the surveyed area was divided into southern and northern parts with the line between sampling stations S13 and S36 as the boundary,the phytoplankton abundance in April was higher in the southern part than in the northern part and contrary in August,which showed an evident seasonal variation of the phytoplankton abundance distribution.The biodiversity were low in this area with the diversity indexes of 1.31 and 1.58 in April and August respectively.The evenness indexes in April and August were low too,which were 0.324 and 0.413 respectively.Comparison with historical data(from 2005 to 2008) showed that the phytoplankton community composition was not stable,the dominance of single dominant phytoplankton was becoming increasingly evident and the biodiversity index presented a declining tendency in Hangzhouwan Bay.更多还原