中文摘要：

基于2005年3月-2006年11月对马鞍列岛海域进行的采样调查及后续实验，探讨了该海域浮游植物优势种类的粒径分布及其季节变化特点，分析了水温、营养盐、悬浮物等环境因子对浮游植物粒径变化的影响。结果表明，马鞍列岛海域浮游植物粒径组成主要受琼氏圆筛藻（Coscinodiscus jonesianus（Grev．）Ostf）、窄隙角毛藻（Chaetoceros affinis Lamx）、拟旋链角毛藻（Chaetoceros pseudocurvisetus Mangin）、中华盒形藻（Bidduphia sinensis Greville）、佛氏海毛藻（Bidduphia sinensis Greville）以及夜光藻（Noetiluca scientillans）等优势种的季节变化趋势所影响，分布范围在8．7μm～396．7μm之间，其中小型浮游植物比例为65．2％，硅藻和甲藻的平均粒径分别为44．3μm和141．5μm，浮游植物平均粒径的最小和最大值分别出现在8—11月和3—5月；硅藻粒径组成与水温成显著线性负相关（R^2=0．64、P〈0．01），与该海域限制性营养盐氮的浓度成显著正相关（R^2=0．65、P〈0．01），硅藻体积与水温及氮营养盐的关系为当水温上升1℃，体积减小6．5％，而当氮营养盐上升1μg/L时，体积增大0．37％。甲藻粒径组成对悬浮物浓度的显著负线性相关大于硅藻，其粒径变化与悬浮物浓度的数值对应关系约为悬浮物浓度每升高1mg／L甲藻粒径减小1．73％，硅藻粒径的降低幅度为甲藻的1／2。

英文摘要：

Based on the date of a series of investigations in Ma＇an Archipelago from May. 2005 to Nov. 2006, we explored the seasonal variation of equivalent spherical diameter （ESD） about phytoplankton dominant species, and analyzed the influence factors like water temperature, nutrition and suspended solid on the variation. The results show that the ESD of the phytoplankton in Ma＇an Archipelago was affected by the seasonal variation of Coscinodiscus jonesianus （Grey.） Ostf, Chaetoceros affinis Lamx, Chaetoceros pseudocurvisetus Mangin, Bidduphia sinensis Greville, Thalassiothrix frauenfeldii （Grun.） Grunow, Noctiluca scientillans and so on. The range of the ESD of phytoplankton in this area was from 8.7μm to 396.7 μm, 65.2% was micro-phytoplankton, and the average ESD of diatom and dinoflagellate were 44.3 μm and 141.5 μm, respectively. The maximum and minimum average ESD of phytoplankton showed up in Aug. to Nov. and Mar. to May, respectively. ESD of diatom was positive linear correlation with temperature （R^2 = 0.64, P 〈 0.01 ）, and was negative linear correlation with N-nutrition （ R^2 = 0. 65, P 〈 0.01 ）. The relationships between the ESD＇s change rate and water temperature and N-nutrition were -6.5%℃ and 0.37%/μg/L, respectively. The ESD of phytoplankton was negative linear correlation with suspended solid, and the correlation of dinoflagellate was more distinct than diatom. When increasing the concentration of suspended solid ling/L, the ESD of dinoflagellate was reduced 1.73%, and the reducing rate of diatom was half of dinoflagellate.