钦州湾表层水分粒级Chl a分布特征及其影响因素

于2014年1月（冬季）和10月（秋季）对钦州湾海域进行了综合调查，分析了该海区分粒级Chl a的分布特征及其影响因素。结果表明，冬季Chl a平均浓度为2.38μg/L，秋季Chl a浓度显著升高，平均浓度为6.96μg/L。浮游植物粒级结构具有明显的季节变化特征，冬季浮游植物粒级组成以微型浮游植物为主，平均占Chl a总量的73.0%，小型和微微型浮游植物所占的比例分别为14.9%和12.1%；秋季，小型、微型和微微型浮游植物对Chl a总量的贡献率分别为42.3%、44.7%和12.9%。浮游植物平均粒级指数秋季（23.55μm）显著大于冬季（11.23μm）。从空间分布上看，在高营养盐含量区域大粒径的浮游植物占有优势，而其他靠近外海一侧的站位则以微型浮游植物为主。温度、营养盐和悬浮物是影响钦州湾海域浮游植物粒级Chl a分布和组成的重要环境因子。

Distribution of size-fractionated Chlorophyll a and its controlling factors in the surface waters of Qinzhou bay

The distribution of size structure of phytoplankton biomass in surface waters, as measured by chlorophyll a (Chl a), was studied in Qinhou bay during winter and autumn in 2014. In winter and autumn, average total Chl a concentration was 2.38μg/L and 6.96μg/L, respectively. Phytoplankton biomass was dominated by nano-phytoplankton in winter, accounting for 73.0% of the total Chl a concentration, followed by micro-phytoplankton with 14.9% and pico-phytoplankton with 12.1%. In autumn, micro-, nano-and pico-phytoplankton contributing to 42.3%, 44.7% and 12.9% of the total Chl a concentration respectively. The average size index of phytoplankton was higher in autumn (23.55μm) than in winter (11.23μm). As a general trend, lager phytoplankton (>20μm) contributed significantly to the biomass in nutrient-repleted waters, and the relative proportions ofnano-and pico-phytoplankton increased from the north to the south in the study area.Temperature, nutrients and suspended solids seems to be the main factors controlling the distribution and variation of size-fractioned Chl a in the surface waters of Qinzhou bay.