富营养化对浅水湖泊轮虫种群结构影响研究

石臼湖和固城湖是长江中下游两个浅水湖泊，富营养化问题日益突出。为探索湖泊富营养化对轮虫的影响，于2012年平水期和枯水期对这两个湖泊轮虫种群结构进行了调查，并检测水体理化因子，分析轮虫分布与水环境因子及水体富营养状况的关系。水质检测结果显示，平水期石臼湖除个别点水体综合营养状态指数（TLI）〉50为轻度富营养状态外，大多数站点TLI50，处于轻度-中度富营养化状态。水生生物调查检出轮虫35种，其中石臼湖33种，固城湖27种，平水期种类多于枯水期。出现的轮虫以臂尾轮虫（Brachionus）和异尾轮虫（Trichocerca）居多，优势种主要有螺形龟甲轮虫（Keratella cochlearis）、广生多肢轮虫（Polyarthra vulgaris）、疣毛轮虫（Trichocerca sp.）、沟痕泡轮虫（Pompholyx sulcata）、异尾轮虫属和臂尾轮虫属等。轮虫平均密度3023.19 ind·L-1，平均生物量745.72μg·L-1。现存量季节变动明显，大部分站点平水期大于枯水期。轮虫多样性指数也是平水期大于枯水期，石臼湖轮虫多样性大于固城湖。水体综合营养状态指数（TLI）与轮虫种类数和多样性成显著负相关，随着富营养化加剧，轮虫种类减少，多样性降低。典范对应分析（Canonical Correspondence Analysis，CCA）表明，影响轮虫种群分布的主要环境因子为NH4＋-N、TN、TP和CODMn。按轮虫丰度分布与水环境因子的关系排序，2次调查的24个站点可大致分成3个组。轮虫种群结构受水体富营养状态影响，每组站点的代表性种类对水体营养状态有较好的指示作用。组1的代表性种类为曲腿龟甲轮虫，指示营养级别O-β；组2代表性种类萼花臂尾轮虫，指示的营养级别为β-α；组3以O营养级种类为主。

Impact of Eutrophication on Rotifer Community Structure in Shallow Lakes

Shijiu Lake and Gucheng Lake are two shallow lakes in the middle and downstream areas of the Yangtze River. The lake eutrophication in the lakes has attracted wide attention. To explore the influence of eutrophication on rotifers, an investigation on rotifer community structure were carried out in normal season and dry season in 2012. At the same time water quality parameters were tested to study the relationship between the rotifers distribution and water quality including the eutrophication status. The results showed that almost of sites in Shijiu Lake were mesotrophic （Trophic Level Index, TLI50）. However in dry season, both lakes were mesotrophic （TLI〉50）. The investigation of aquatic organism showed that 35 species of rotifers were detected in total. There were 33 species in Shijiu lake and 27 species in Gucheng lake. the species were more in normal season. The frequency of Brachionus and Trichocerca was the highest. The dominant species were Keratella cochlearis, Polyarthra vulgaris, Trichocerca sp, Pompholyx sulcata, Trichocerca sp and Brachionus sp. The average density of the rotifers was 3023.19 ind·L-1 and the average biomass was 745.72 μg·L-1. The seasonal changes were obvious in the standing crop. The standing crop in the normal season was higher than in the dry season in almost of the sites. Rotifers diversity index was higher in Shijiu lake. TLI was significantly negatively related to the rotifers species number and diversity. With the increasing of nutrient loading, rotifer species and diversity decreased. Further, Canonical Correspondence Analysis（CCA） showed that the main water qualtiy factors affecting the rotifer species distribution were NH4＋-N, TN,TP and CODMn. According to the sort of the relationships between the rotifer abundance and the water environment factors, 24 sites can be roughly divided into three groups. The results showed that Rotifer community structure was affected by eutrophication, and the representative species in each group had a good indication on the t