芡实分区刈割试验对陈瑶湖后生浮游动物群落结构的影响

Abstract

陈瑶湖流域是长江中下游重要的水禽省级自然保护区，近年来随着农业的发展，湖区存在芡实种植过密，汛期影响行洪的隐患，对湖区的水生态系统结构与功能的稳定性造成严重影响。为研究芡实分区刈割试验对陈瑶湖后生浮游动物群落结构的影响，于2019年8月期间对陈瑶湖后生浮游动物进行调查。共鉴定出后生浮游动物15科22属40种，其中轮虫12属26种，枝角类8属11种，桡足类2属3种，群落结构主要以轮虫为主，后生浮游动物种类分布时空上无显著差异（P>0.05）。共发现优势种8属10种，分别为萼花臂尾轮虫（Brachionus calyciflorus）、角突臂尾轮虫（Brachionus angularis）、剪形臂尾轮虫（Brachionus forficula）、螺形龟甲轮虫（Keratella cochlearis）、囊形单趾轮虫（Monostyla bulla）、蹄形腔轮虫（Lecane ungulata）、针簇多肢轮虫（Polyarthra trigla）、迈氏三肢轮虫（Filinia maior）、长额象鼻溞（Bosmina longirostris）和广布中剑水蚤（Mesocyclops leuckarti）。后生浮游动物密度和生物量平均值分别为（1681.49±205.73）个/L和（7.8±1.52） mg/L，密度和生物量峰值均出现在初期的未刈割区，最低值均出现在后期的河道。后生浮游动物密度的空间分布呈现未刈割区 > 刈割区 > 河道的特征，时间变化呈现刈割初期 > 前期 > 中期 > 后期的趋势，生物量的时空变化趋势与密度一致。ShannonWiener多样性指数、Margalef丰富度指数和Pielou均匀度指数变化范围分别为1.67-3.42、1.64-3.57和0.41-1.13.统计分析结果表明TN、TP、NH₄⁺-N、Chl.a、EC和SD是影响浮游动物群落结构的主要因子。综合生物和理化指标判别陈瑶湖水体已处于中污染状态；营养状态参数结果表明，陈瑶湖已处于中度富营养状态。;Chenyao Lake basin is an important waterfowl Provincial Nature Reserve in the middle and lower reaches of the Yangtze River,In recent years, with the development of agriculture, there are some hidden dangers in the lake area, such as planting too much Euryale ferox, affecting the flood discharge in flood season, and seriously affecting the stability of the structure and function of the aquatic ecosystem in the lake area.In order to study the effects of mowing experiment in different areas of Euryale ferox on the community structure of metazoan zooplankton in Chenyao Lake, the metazoan zooplankton was investigated in August 2019. A total of 40 species of metazooplankton belonging to 22 genera, 15 families were identified. Among them, 26 species belong to 12 genera of Rotifer, 11 species belong to 8 genera of Cladocera and 3 species belong to 2 genera of Copepoda,The community structure was dominated by Rotifers,There was no significant difference in the spatial and temporal distribution of metazoan zooplankton (P>0.05). A total of 8 genera and 10 species of dominant species were found,including Brachionus calyciflorus, B. angularis, B. forficula,Keratella cochlearis, Monostyla bulla, Lecane ungulata, Polyarthra trigla, Filinia maior, Bosmina longirostris and Mesocyclops leuckarti. The average animal density and biomass of metazoan zooplankton were (1681.49 +205.73) ind/L and (7.8+1.52) mg/L respectively,The peak values of density and biomass appeared in the initial stage of no mowing area and the lowest values all appeared in the later stage of channel.The spatial distribution of the density of metazoan zooplankton showed the characteristics of no mowing area > mowing area > river channel, while the temporal change trend was in the initial stage > early stage > middle stage > late stage. The trend of spatial and temporal variation in biomass and density was consistent. The Shannon Wiener diversity index, Margalef richness index and Pielou evenness index of the metazoan zooplankton community were 1.67-3.42, 1.64-3.57 and 0.41-1.13, respectively. The results of Redundancy analysis and Pearson correlation analysis showed that TN, TP, NH₄⁺-N, Chl a, EC and SD were the main factors affecting the community structure of zooplankton. According to the comprehensive biological and physical and chemical indicators, Chenyao Lake was in a state of moderate pollution. The results of nutritional parameters indicated that Chenyao Lake was in a state of moderate eutrophication.