岱衢洋海域2010~2011年网采浮游植物群落特征与水质评价

基于2010年春季（5月）、夏季（8月）、秋季（11月）和2011年冬季（2月）对岱衢洋海域进行的4个航次网采浮游植物的调查资料，对该海域浮游植物的种类组成、优势种、细胞丰度分布以及生物指数与环境因子的相关性进行调查研究，并用富营养化指数、水质综合指数、浮游植物多样性指数进行水质状况评价.经初步分析，共鉴定出浮游植物50属116种，其中硅藻门37属92种，甲藻门10属20种，绿藻门和蓝藻门各2种.全年浮游植物优势种主要为硅藻门的琼氏圆筛藻（Coscinodiscus jonesianus）、星脐圆筛藻（Coscinodiscus asteromphalus）和中肋骨条藻（Skeletonema costatum）.浮游植物种类数呈现由近岸向远岸递减的趋势，季节差异极显著（p=0.008<0.01），春季最少（33种），冬季最多（71种）.浮游植物细胞丰度呈北高南低的趋势.夏季浮游植物细胞丰度最高，达67.66×10⁶ cells·m^-3，春季最低，为0.12×10⁶ cells·m^-3，两季节差异极显著（p=0.003<0.01）.夏季靠近衢山岛一侧的D03和D05站位，尖刺拟菱形藻（Pseudo-nitzschia pungens）大量增殖，但未达到赤潮水平.冬季岱衢洋海域的浮游植物多样性指数最高，物种较丰富.春季均匀度指数最高，多样性指数也较高，但丰富度指数最低.相关性分析表明，浮游植物群落分布与水温、盐度、透明度、叶绿素a及营养盐等环境因子存在一定的相关性.富营养化指数表明，整个海域夏冬季多数站位均未发生富营养化，春秋季均处于富营养化状态，且春季富营养化最严重，多数站位处于中度富营养化状态.水质综合指数表明，整个海域处于轻污染状态，且夏冬秋季水质明显优于春季.浮游植物多样性指数表明，该海域除秋季处于重中度污染状态外，其他季节均处于轻中度污染状态.

Community structures and water quality evaluation of the net-phytoplankton in Daiquyang,Zhejiang Province

Marine phytoplankton, as the primary producers of the marine ecosystem, which undertake the material cycle and energy flow by converting solar energy into organic energy through photosynthesis, have an important influence on marine fishery resources and global climate change. Based on the data from four seasonal oceanographic surveys in Daiquyang during spring (May), summer (August), autumn (November) of 2010, and winter (February) of 2011, the species composition, dominant species, cell abundance distribution of phytoplankton, the biotic index and their correlations with environmental factors were analyzed.Furthermore, seawater quality was evaluated by means of eutrophication index (E), water comprehensive pollution index (A_com) and phytoplankton diversity index (H'). A total of 116 species of 50 genera were identified, among which, 92 species belonged to 37 genera of diatoms, 20 species belonged to 10 genera of dinoflagellates, 2 species belonged to chrysophyta, and 2 species belonged to cyanophyta. In the whole year, the dominant species were Coscinodiscus jonesianus, Coscinodiscus asteromphalus and Skeletonema costatum. The number of species had a trend decreasing from the inshore to the offshore, and varied significantly among different seasons (p=0.008<0.01) with the least in spring(33 species) and the most in winter (71 species). In addition, on the spatial distribution, the cell abundance was higher in the north than in the south. There was an obvious annual change in the cell abundance, with the highest in summer (67.66×10⁶ cells·m^-3) and the lowest in winter(0.12×10⁶ cells·m^-3), which varied very significantly between summer and spring (p=0.003<0.01). Pseudo-nitzschia pungens could multiply rapidly in summer in stations D03 and D05 near Qushan island, but did not cause red tides. In winter, the diversity index was the highest, and the number of species was richer. In spring, the evenness index was the highest among four seasons, but the richness index was the lowest. Correlation analysis demonstrated that the distribution of phytoplankton community had definite correlations with water temperature, salinity, water transparency, chlorophyll a, nutrient and other environmental factors. Eutrophication index (E) showed that eutrophication would not be induced at most investigation stations in summer and winter, but induced in spring and autumn. Worse still, eutrophication was more serious in spring, most stations were in moderate. Water comprehensive pollution index (A_com) showed that the whole area was in the state of slight pollution, water quality in spring was worse than other seasons. Phytoplankton diversity index (H') showed that autumn was in the state of heavy moderate pollution, and other seasons were basically in light moderate pollution.