中文摘要：

分析了2004年2月珠江口小型原生动物（包括鞭毛虫、纤毛虫和异养甲藻）的分布特征，探讨了环境因子对其分布的影响。结果表明，鞭毛虫在珠江口的丰度为3．4×10^3～25．6×10^3个／mL，异养甲藻的丰度为11～312个／mL，纤毛虫的丰度为7～172个／mL。高丰度的原生动物主要集中在广州附近盐度为2～5的河口上段，而低丰度在外海盐度超过30的下段区域，原生动物的3个类群的丰度均从上段往下段呈递减的趋势。原生动物的分布特征与浮游植物叶绿素a的分布特征相似，原生动物也与细菌呈显著的正相关，表明细菌和浮游植物影响着原生动物在珠江口内的分布。冬季温度对原生动物的分布不具有直接的影响作用，而营养盐可能是通过影响浮游植物及细菌的分布而间接对原生动物的分布产生影响。原生动物的丰度表明珠江口部分水域已处于富营养化和超营养化状态。

英文摘要：

Based on the data obtained from a cruise in Feb. 2004, abundance, spatial distributions and controlling factors of nanoflagellates, heterotrophic dinoflagellates and ciliates in the surface layer in the Pearl River estuary were studied. Nanoflagellates abundance ranged from 3.4×10^3 to 25.6 ×10^3 cells/mL, while heterotrophic dinoflagellates ranged from 11 to 312 cells/mL and ciliates were from 7 to 172 cells/mL, respectively. High abundance of these protozoa was observed at upper stream of the estuary near the Guangzhou waters with low salinity （2 to 5 psu）. Low abundance was observed at lower stream of the estuary with high salinity （〉30 psu）. The three groups of protozoa abundance decreased from upper estuary near Guangzhou to lower estuary. The distribution patterns of these protozoa abundance were similar to that of chlorophyll a, and they had a significant relationship with bacteria, indicating that phytoplankton and bacteria influence protozoa distribution patterns. Temperature and nutrients were not direct factors influencing protozoa distribution. High abundance of protozoa suggested that the Pearl River Estuary was eutrophic water.