太湖湖滨带浮游植物群落特征及指示种筛选

针对太湖湖滨带,均匀布设49个点位,分别于2009年12月、2010年4、8月开展浮游植物及水质监测。结果显示,湖滨带浮游植物群落多样性整体较低,优势种从枯水期到丰水期呈"鱼腥藻-鱼腥藻-微囊藻"的演变趋势;西北部湖区(竺山湖、梅梁湾、西部沿岸)浮游植物密度明显高于东南部湖区(东部沿岸、东太湖、南部沿岸);湖滨带浮游植物群落结构与湖体相似,密度比湖体高1个数量级;RDA排序筛选出在显著水平上解释浮游植物分布的最小变量组合为TN、CODMn、SS、p H、SD,且方差分解指出TN是相对最重要的变量;当物种适合度为50%~100%时,与TN具有较好梯度响应关系的是四尾栅藻及弓型藻,并且这2个种与TN、TP及综合营养状态指数的组合变量也有较好的梯度响应关系,具备指示太湖湖滨带富营养化的可能,但定量指示意义尚待进一步研究。

Community Structure of Phytoplankton and Selection of Indicator Species in the Littoral Zone of Lake Taihu

To explore the characteristic of phytoplankton communities and their response to ecological changes in the littoral zone of Lake Taihu, we carried out an investigation on phytoplankton and water quality among December 2009, April 2010 and July 2010. The density of Cyanobacteria was much higher than that of other taxa, with the dominance of Mycrocystis sp. gradually significant from dry season to wet season. In spatial, the algae density of Zhushan Bay, Meiliang Bay and west lake side zone was obviously higher than East Taihu Lake, east and south lake side zone, but the diversity was low throughout the whole littoral zone of Lake Taihu. Compared with other studies, the community structure in the littoral zone was similar to that of major body of Lake Taihu, as well as spatial and temporal distribution characteristics. However, due to the effects of wind, water flow and aquatic vegetation, algae accumulation was more likely to occur in the littoral zone of Lake Taihu. Multivariate analysis was used to study the stress response between algae and water quality. The maximum gradient length was 1.88, calculated by detrended correspondence analysis(DCA), and the linear ordination model was acceptable. Redundancy analysis(RDA) indicated that the minimum combination including TN, COD_Mn, SS, pH, SD can significantly explain the variations of the phytoplankton communities. The result of variance partitioning showed that TN was the most important variable affecting phytoplankton community in the littoral zone of Lake Taihu. Under a species fit range from 50% to 100%, Scenedesmus quadricauda and Schroederia sp. were finally selected as the indicator species. The abundance of Scenedesmus quadricauda decreased as the TN increased, and the abundance of Schroederia sp. increased as the TN increased. They still had a good stress response to phosphorus and trophic state index(TSI), but the quantitative dose-response was not as yet fully understood.