Spatial and temporal variation in rotifer community structure and the response to environmental factors among different water bodies in Guangzhou City

Abstract

轮虫是水体中重要的浮游生物类群，对环境变化敏感，是水生态系统中食物链及微型食物网的关键环节.于2015年夏季（7月）和冬季（12月）对养殖池塘、水库、广州城市湖泊、珠江河口及珠江河段水域的轮虫和理化环境指标进行了调查分析，共发现轮虫26属、76种，其中裂痕龟纹轮虫（Anuraeopsis fissa）在7月河流水体占绝对优势，但12月数量明显减少.冬季珠江河段和河口水体群落多样性指数与均匀度指数较夏季高，群落结构较夏季稳定.调查水体轮虫丰度范围为33~2625 ind./L，城市湖泊夏季丰度较高，冬季有所下降，而养殖池塘轮虫丰度在冬季有所上升.群落结构相似性分析（ANOSIM）分析表明，不同类型水体之间差异显著，尤以湖泊与河流差异性最大，广布多肢轮虫（Polyarthra vulgaris）在湖泊贡献率最高，暗小异尾轮虫（Trichocerca pusilla）其次；裂痕龟纹轮虫在河流贡献率最高，优势种丰度差异是造成湖泊与河流群落结构差异的主要原因.统计分析表明，轮虫丰度与叶绿素a浓度呈正相关.冗余分析与ANOSIM分析发现广布多肢轮虫在流花湖等叶绿素a浓度较高的静态水体中易形成优势；裂痕龟纹轮虫和角突臂尾轮虫（Brachionus angularis）在珠江河段等总氮和总磷浓度高的富营养化流动水体中易形成优势.综合轮虫群落结构和水质特征，广州市水体富营养化严重，耐污性轮虫种类多，应加强城市水生态系统保护和管理.;Rotifers, a kind of essential plankton in aquatic ecosystem, is sensitive to environmental changes and playes an important role in food chain and microbial foodweb. Environmental factors and rotifer samples were collected from five type of water bodies (lake, pond, river, reservoir and estuary) in July and December, 2015, Guangzhou City. A total of 76 specie was identified, which belonging to 26 genera. The dominant species were Anuraeopsis fissa, in river in July and decreasing in December. The evenness index and the diversity index of river and estuary in winter were much higher than those in summer. Rotifer abundance ranged from 33 to 2625 ind./L. The abundances of rotifer in city lakes in summer were higher than those in winter, while opposite situation for the ponds. Analysis of similarities(ANOSIM) determined that the community structure was significant different among the different water bodies. These differences came from the abundance of dominant species, especially the river and lakes. Owing to the largest contribution rate of lakes made by Polyarthra vulgaris and that of river made by Trichocerca pusilla and A. fissa, the community structure of rotifers was significantly different. Statistical analysis showed that there was a positive correlation between chlorophyll-a concentrations and rotifer abundance. Redundancy analysis and ANOSIM analysis represented that P. vulgaris was more likely to dominated in lentic water, such as Lake Liuhua which contented of high chlorophyll-a concentration. A. fissa and Brachionus angularis were dominant in the Guangzhou segment of the Pearl River, the lotic waters with high total nitrogen and total phosphorus concentrations. In summary, the waters in Guangzhou City were eutrophic and measures should be taken to protect urban aquatic ecosystem.