中文摘要：

于2011年7月（夏季）和10月（秋季）对大亚湾近岸海域粒径分级叶绿素a浓度进行分析,研究了浮游植物的粒级结构特征及环境影响因素。结果表明,夏季叶绿素a平均浓度为4.07μg/L;秋季叶绿素a平均浓度为5.09μg/L,高值均出现在澳头附近水域,低值出现在大鹏澳附近水域。各粒级浮游植物叶绿素a浓度对叶绿素a总量的贡献存在季节差异。夏季大亚湾水体以微型浮游植物（nanophytoplankton,2～20μm）占优势,占叶绿素a总量的47.8%;小型浮游植物（microphyto-plankton,20～200μm）和微微型浮游植物（picophytoplankton,〈2μm）的贡献率分别为31.2%和22.5%。秋季以小型浮游植物占优势,占叶绿素a总量的62.9%;微型和微微型浮游植物所占比例分别为18.1%和19.0%。秋季营养盐对浮游植物的生长是充足的,粒径较大的小型浮游植物对光照和营养盐具有竞争优势,夏季浮游植物受到营养盐的限制。浮游植物分粒级叶绿素a和环境因子的相关分析结果表明,夏季盐度是影响大亚湾近岸水域浮游植物粒级生物量分布和组成的重要环境因子,秋季,小型浮游植物生物量与营养盐显著相关,微型浮游植物与温度显著正相关。

英文摘要：

Size-fractionated chlorophyll-a（Chl a） were determined in coastal water of Daya Bay in July and October 2011,with the aim of investigating the distribution of phytoplankton size structure and the environmental factors that affected this distribution.The average Chl a concentrations in summer and autumn were 4.07 g/L and 5.09 g/L,respectively.The Aotou showed highest total Chl a concentrations and Dapeng Ao showed the lowest values in both summer and autumn.In summer,the phytoplankton in the Daya Bay was dominated by nanophytoplankton,accounting for 47.8% of the total Chl a concentration,followed by microphytoplankton（31.2%）,and picophytoplankton（22.5%）.In autumn,microphytoplankton become the dominant fraction（62.9%）,and the levels of the nanophytoplankton and picophytoplankton were approximately equal.Nutrient concentrations were assumed to be saturated for phytoplankton growth in autumn,thus microphytoplankton may be at a competitive advantage for nutrient and light.In summer,phytoplankton assemblages were limited by nutrients.Correlation Analysis of size-fractionated chlorophyll a with environmental factors showed that salinity was the main factor affecting the distribution and composition of size-fractionated phytoplankton biomass in summer,whereas microphytoplankton and nanophytoplankton were correlated with nutrient and temperature,respectively,in autumn.