中文摘要：

基于2003--2010年间对胶州湾分粒级叶绿素口浓度的连续观测，系统研究了胶州湾浮游植物粒级结构的季节变化、年际变化及长期变化特征。结果表明，胶州湾表层浮游植物粒级组成以小型和微型浮游植物为主，其浓度由东北部和北部向湾中间及湾外逐渐递减。不同区域分粒级叶绿素a浓度的季节与年际变化规律相似。小型和微型浮游植物表现出明显的双峰型季节变化，小型浮游植物的高峰值通常出现在冬季，而微型浮游植物则出现在夏季。长期变化结果表明，冬季小型浮游植物所占比例自90年代起表现为增加的趋势，而夏季的变化规律与冬季相反，自1998年开始，小型浮游植物所占比例下降，微型浮游植物比例有所上升。春季和秋季小型和微型浮游植物的贡献率没有表现出明显的升高或降低趋势，但微微型浮游植物的贡献率在2000年之后显著低于2000年之前。统计分析结果表明，温度、营养盐浓度与结构是影响胶州湾浮游植物粒级结构变动的重要因素。

英文摘要：

On the basis of the monthly observation of concentrations of size-fractionated Chl.a during 2003--2010, the phytoplankton size structure and its seasonal, annual, and long term changes in Jiaozhou Bay were studied. Results indi- cated that the micro- and nano-phytoplankton were the main components in the phytoplankton community in Jiaozhou Bay. The concentration of Chl.a decreased from the north and northeast to the middle and the south of the bay. The seasonal and annual changes of the size-fractionated Chl.a concentrations were similar in different areas of the bay. The micro- and nano-phytoplankton showed a seasonal change of double-peak, with the micro-phytoplankton peak in winter and nano- phytoplankton peak in summer. The percentage of the micro-, nano- and pico-phytoplankton in different areas were similar. The results of the long term changes indicated that the percentage of the micro-phytoplankton was increasing since 1990s in the winter, and the nano-phytoplankton percentage increases in the summer. The percentage of pico-phytoplankton sig- nificantly decreased after 2000. The temperature, the concentration and structure of nutrients were important factors af- fecting the change of the size fractionated Chl.a in Jiaozhou Bay.