The present study aimed to investigate the changes of zooplankton community before and after the spring closed season in the Pearl River. Four ecological investigations annually were carried out on zooplankton and water samples at Fengkai, Zhaoqing and Modaomen of Pearl River before (March), during (April and May) and after (June) closed fishing in 2014 and 2015. The community structure, including the distributions of species composition, dominant species, standing crop and biodiversity, was investigated. The correlation between the community structure of zooplankton and the environmental factors was discussed. Records showed that there were 88 species of zooplankton and the dominant species were Brachionus calyciflorus, Mesocyclops leuckarti, Brachionus angularis, Brachionus angularis and Limnoithona sinensis. Zooplankton had an average abundance of three sampling points ranging from 2579 to 2957 ind·L-1, which was higher in May than April and that of March was followed and that of June was lowest. The average abundance of zooplankton of three sampling points was 0.871 mg·L-1, which was higher in March than May and that of April was followed and that of June was lowest. In the whole investigation period, the Shannon-Wiener diversity indexes and evenness indexes increased from March to June, and the average values of the Shannon-Wiener diversity indexes and evenness indexes were 2.85, 0.91, respectively. The results of principal component analysis (PCA) showed that the dominant species abundance in Fengkai was closely correlated with the total nitrogen content and pH value; the abundance of dominant zooplankton species inluding Brachionus calyciflorus, Brachionus angularis and Limnoithona sinensis in Zhaoqing showed very significantly positive correlation with the total nitrogen content and was significantly positively correlated with the total phosphorus content, the ammonia nitrogen content, permanganate index and chlorophyll a content, while significantly negatively correlated with water transparency and dissolved oxygen content; the dominant species abundance in Modaomen was closely correlated with environment factors, such as water transparency, dissolved oxygen content, the total phosphorus content, and chlorophyll a content. We concluded that zooplankton community changed obviously before and after the spring closed season in the Pearl River artery, which was influenced by many factors such as nutrients.%为探究珠江春季禁渔前后浮游动物群落变化特征,深入分析浮游动物群落对珠江春季禁渔的响应,为珠江流域的渔业资源和生物多样性保护积累基础数据,于2014—2015年3—6月,在西江上游至下游河口设置封开、肇庆和磨刀门3个采样点每年开展4次浮游动物及水质调查.分析了浮游动物的种类组成和优势种分布、浮游动物现存量和生物多样性指数的分布,探讨了浮游动物群落结构与环境因子的关系.调查期间共检出浮游动物88种(未包括无节幼体及桡足幼体).萼花臂尾轮虫(Brachionus calyciflorus)、广布中剑水蚤(Mesocyclops leuckarti)、角突臂尾轮虫(Brachionus angularis)、跨立小剑水蚤(Microcyclops varicans)以及中华窄腹剑水蚤(Limnoithona sinensis)等种类在禁渔前、中、后均占有较大优势.浮游动物平均丰度在2579~2957 ind·L-1范围内波动,3个采样点平均丰度变化趋势为:5月>4月>3月>6月,平均生物量变化趋势为:3月>5月>4月>6月.浮游动物生物多样性指数和均匀度指数从3—6月均总体呈现上升趋势,生物多样性指数和均匀度指数均值分别为2.85和0.91.PCA分析表明:封开浮游动物优势种类丰度与总氮和pH等环境因子显著相关;肇庆浮游动物优势种类丰度与总氮呈极显著正相关,与高锰酸盐指数和叶绿素a含量呈显著正相关,与溶解氧呈显著负相关;磨刀门浮游动物优势种类丰度与透明度呈显著正相关,与总磷呈显著负相关.可以看出,禁渔前后珠江干流浮游动物群落发生了明显变化,且受到营养盐等诸多因素的影响.
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