安庆西江浮游动物群落结构及江豚生存状况评估

为了解安庆西江浮游动物群落结构, 进而评价江豚(Neophocaena asiaeorientalis asiaeorientalis)的生存状况, 于2015年4月至2016年1月对西江浮游动物和环境因子进行了季节性调查。研究结果表明: (1)共采集浮游动物55种, 其中原生动物13种、轮虫27种、枝角类9种、桡足类6种。4个季节间浮游动物种类数差异较大, 夏季种类数最多, 为39种; 冬季种类数最少, 仅为16种。(2)全年浮游动物平均密度和生物量分别为4115 ind./L和1.735 mg/L, 且均以原生动物和轮虫为主。方差分析结果表明, 不同季节间浮游动物密度和生物量均存在显著差异, 且夏季浮游动物密度和生物量均显著高于其他3个季节。(3)全年共记录优势种12种, 其中原生动物4种、轮虫6种、桡足类2种; 不同季节间浮游动物优势种的组成差异明显。(4)采用浮游动物生物量对水质的评价结果显示西江水体处于中营养状态; 运用Shannon多样性指数和Margalef多样性指数对水质的评价结果显示西江水体处于α-中污状态, 表明西江水质基本上满足江豚生存需求。(5)依据浮游动物的现存量, 估算出西江食浮游动物鱼类的渔产力为54340.2 kg, 相应地可满足36头江豚的营养需求。研究结果不仅有助于了解长江故道这种特殊水体浮游动物的群落特征, 还对迁地保护区江豚的保护有重要意义。

COMMUNITY STRUCTURE OF ZOOPLANKTON AND ITS RELATIONSHIP WITH SURVIVABILITY OF THE YANGTZE FINLESS PORPOISE IN XIJIANG OXBOW,ANQING CITY

The Xijiang Oxbow in Anqing City belongs to the old course of the Yangtze River. It is the third ex situ conservation zone for Yangtze finless porpoise (YFP, Neophocaena asiaeorientalis asiaeorientalis) in China. To understand the community structure of zooplankton and assess the survivability of the YFP, a field investigation of seasonal variation of zooplankton and environmental parameters was conducted in Xijiang Oxbow from April 2015 to January 2016. The results showed that: (1) a total of 55 species were identified, and the number of species belonging to Protozoa, Rotifera, Cladocera and Copepoda was 13, 27, 9 and 6, respectively. The number of zooplankton species varied greatly between seasons, with the most number during summer (39 species) and the least number during winter (16 species). (2) The annual average density and biomass of zooplankton in Xijiang Oxbow were 4115 ind./L and 1.735 mg/L respectively, both of which were dominated by Protozoa and Rotifera. One-way ANOVA analysis showed that the density and biomass of zooplankton were significantly higher in summer compared with other seasons. (3) A total of 12 main species were recorded throughout the whole year, including 4 Protozoa, 6 Rotifera, and 2 Copepoda. The dominant species composition differed between seasons. (4) The assessment results of water quality showed that the Xijiang Oxbow was classified as mesotrophic level considering the biomass of zooplankton, and α-mesosaprobic using Shannon-Weiner species diversity and Margalef species richness index. It was indicated that the water quality satisfied the living requirement for YFP. (5) Based on the standing crop of zooplankton, it was estimated that the fish productivity in Xijiang Oxbow is about 54340.2 kg, which could meet the nutrition requirements of 36 YFPs. The results of this study not only improved the understanding of the community structure of zooplankton in Oxbow waters, but also have important implication to the protection of YFP in ex situ reserve.