中文摘要：

为掌握昌黎黄金海岸国家级自然保护区近海岸水域生态环境的变化趋势,于1999—2013年对该保护区海域开展了连续15年的生态调查工作。结果表明：保护区浮游植物共计3门23科43属136种,其中硅藻116种,甲藻19种,金藻1种;种类数年际变化呈下降趋势,优势种年际变化差异极显著;15年中浮游植物细胞密度出现两个高峰期;种类数年际变化与p H呈显著负相关关系（r=-0.565,P〈0.05）,而年际的Shannon-Wiener指数（H＇）与盐度呈显著正相关关系（r=0.521,P〈0.05）,这表明影响浮游植物种类组成的主要因素为p H和盐度;浮游植物种类数与浮游动物密度呈显著负相关关系（r=-0.553,P〈0.05）,这可能与两者间的捕食关系有关。

英文摘要：

Charactdristics and variation trend of phytoplankton community were investigated in Changli Golden Beach National Ocean Nature Preserve from February, May, August, and November of 1999 to February, May, August, and November of 2013. A total of 136 phytoplankton phyla, including 116 species in Bacillariophyta, 19 species in species was found, belonging to 43 genera, and 3 Fyrrophyta and only 1 species in Chrysophyta. There was annual downward trend in species number as elapse of the 15-year survey, with significant difference in num- ber of predominant species. Two peaks of phytoplankton cell density were observed during the 15-year survey, and annual change in species number was inversely related to pH （ r = -0. 565, P〈0.05 ）. However, the annual change in Shanon-Wiener index （H＇） was significantly positively related to salinity （r= 0. 521, P〈0.05 ）, indicating that pH and salinity were the main environmental factors influencing phytoplankton species composition. The phyto- plankton species composition was negatively correlated with zooplankton abundance（ r=-0. 553, P〈0.05 ） ,which may be involved in the predator-prey relation between them.