南宁邕江网箱养殖区浮游生物种群结构特征

浮游生物是评价水体质量的一项重要生物指标,为了解广西南宁邕江网箱养殖区的水质状况,于2009年9月-2010年9月在金陵至清川桥江段网箱养殖区设置2个监测断面,每两个月采样1次,对其水质和浮游植物种群组成、密度和优势种变化进行了系统研究.结果表明:邕江网箱养殖区共检出浮游植物8门98属(种),绿藻、硅藻分别占浮游植物总种数的42.8％、24.5％；共检出浮游动物4大类44属(种),优势种为轮虫类,占浮游动物总种数的43.2％.总体看来,邕江网箱养殖区浮游生物种数夏秋季节多,冬春季节少；浮游生物密度与种数季节变化趋势一致.邕江网箱养殖区综合营养状态指数(TLI)介于59.28-66.87之间,属于中度富营养化水平.Shannon-Wiener多样性及均匀度指数分别介于1.35-1.56和0.2275-0.2586之间,表明邕江网箱养殖区在监测期内处于中营养—富营养状态,这与采用相关加权综合营养状态指数法的评价结果一致.

CHARACTERISTICS OF PLANKTON COMMUNITY STRUCTURE IN THE FISH CAGE CULTURE AREA OF YONGJIANG RIVER

Plankton is an important biological indicator for water quality assessment. In order to understand the water trophic status in the fish cage culture area of Yongjiang River, Nanning City of Guangxi Province, the population composition, quantity and dominant species of plankton were studied based on bimonthly sampling from September 2009 to September 2010. All data were collected from two sampling sites located between Jinling River and Qingchuan River, which was the main cage culture area in Yongjiang River. The results indicated that a total of 8 phyla and 98 species of phytoplankton were identified. The species numbers of Chlorophyta and Bacilla riophyta represented for 42.8% and 24.5% of total species richness. Four phylums and 44 species of zooplankton were identified, in which rotifer dominates 43.2%. In general, more plankton species were found in summer and autumn than that in winter and spring. The seasonal variations of plankton density and species number were identical. The comprehensive trophic level index (TLI) values were between 59.28 and 66.87, which means that the water quality in the fish cage culture area of Yongjiang River was in between mesotrophic and nutritious level. The Shannon-Wiener diversity varied from 1.35 to 1.56, while evenness indices from 0.2275 to 0.2586, it means that the relevant water quality was in between mesotrophic and nutritious level. The studies show that the water trophic status evaluation results of the fish cage culture area along Yongjiang River detected by TLI was consistent with that of the Shannon-Wiener diversity index and evenness indices.