秦山岛周边海域浮游植物群落的季节变化

Seasonal Variation of Phytoplankton Community in Qinshan Island Surrounding Waters

秦山岛位于海州湾中部,周边海域有4条河流汇入,平均水深小于5 m,兼具海岛、河口及滨海湿地的生态系统特征和功能。2015年8月(夏季)、11月(秋季)、12月(冬季)和2016年4月(春季)对秦山岛周边海域5个断面(A~E)20个站位(St.1~St.20)的浮游植物群落进行周年调查。4航次共鉴定出浮游植物6门149种,其中硅藻121种,占总种数的81.21%;甲藻22种,占14.77%;蓝藻3种,占2.01%;绿藻、金藻、裸藻各1种,占0.67%。冬季St.16种数最多,为38种,秋季St.8最少,为3种,年均值21.8种;季节平均种数依次为冬季>春季>夏季>秋季;硅藻比例夏季最低,冬季最高,甲藻比例秋季最低,夏季最高。夏季St.12密度最高,为68.10×10^(4) ind./m 3,秋季St.8密度最低,为0.06×10^(4) ind./m 3,年均值12.90×10^(4) ind./m 3;季节平均密度依次为夏季>冬季>春季>秋季;夏季主要优势种链状亚历山大藻(Alexandrium catenella)、格氏圆筛藻(Coscinodiscus granii)及夜光藻(Noctiluca scientillans)的最大值集中分布于B和C断面的St.8,St.12和St.7,密度高且优势度大,但赤潮风险较低。多样性指数冬季St.15最高,为4.54,夏季St.8与St.20最低,为0.75,年均值3.36;多样性指数的季节平均值依次为冬季>春季>秋季>夏季。调查结果表明,秦山岛周边海域浮游植物群落结构存在明显的季节变化,但断面间群落参数差异不显著。

Qinshan Island is located in the middle of Haizhou Bay.There are four rivers in the surrounding waters,with an average depth of less than 5 m.It has the characteristics and functions of island,estuary and coastal wetland ecosystem.Phytoplankton community in Qinshan Island sea area was seasonally surveyed in Aug.2015(summer),Nov.2015(autumn),Dec.2015(winter)and Apr.2016(spring).A total of 149 species from 6 phylums were identified,including 121 species of Bacillariophyta accounting for 81.21%of total species,22 species of Pyrroptata accounting for 14.77%of total species,3 species of Cyanophyta accounting for 2.01%of total species.Furthermore,there was 1 species of Chlorophyta,Chrysophyta and Euglenophyta,accounting for 0.67%of total species respectively.Maximum species number(38)was collected in St.16 in winter,whereas the minimum(3)was collected in St.8 in autumn,and annual average species number was 21.8.Seasonal average species number from more to less in proper order was winter>spring>summer>autumn.Ratio of Bacillariophyta minimized in summer and reached to peak in winter.However,ratio of Pyrroptata minimized in autumn and reached to peak in summer.Cell density of St.12(68.10×10^(4) ind./m 3)in summer reached to the annual peak,whereas the density of St.8(0.06×10^(4) ind./m 3)in autumn was the minimum,and annual average cell density was 12.90×10^(4) ind./m 3.Seasonal average density from more to less in proper order was summer>winter>spring>autumn.Alexandrium catenella,Coscinodiscus granii and Noctiluca scientillans were the most dominant species in summer.Maximum density of the 3 species was appeared in St.8,St.12 and St.7 of section B and C,the dominance of the 3specis in the 3 stations was significantly high.However,the HABs(harmful algal blooms)risk of the 3 stations was relatively low.Shannon-Weiner index of St.15(4.54)in winter reached to the annual peak,and St.8and St.20 showed the annual lowest Shannon-Weiner index in summer.Annual average Shannon-Weiner index was 3.36.Seasonal average Shannon-Weiner index from more to less in proper order was winter>spring>autumn>summer.The result showed that phytoplankton community structure in Qinshan Island sea sreashowed significant seasonal variation,however,the 5 section showed no significant difference in community parameters.