长江中下游地区湖泊现代沉积硅藻分布基本特征

Distribution of Modern Lake Sediment Diatoms in the Middle and Lower Reaches of Yangtze River Catchment

首次对长江中下游地区45个湖泊表层沉积硅藻进行了分析.根据硅藻多属种百分含量在总磷浓度和营养梯度上的分布规律以及硅藻数据的降维对应分析(DCA)结果表明,硅藻组合响应于湖泊营养态的变化,尤其是当水体接近于富营养态时,硅藻组合出现迅速转变,即以附生、附生浮游、浮游和底栖种类的多生态型的硅藻组合迅速被富营养浮游种为优势的组合取代.由此提出当Cyclostephanos、Stephanodiscus等种类和Cyclotella meneghiniana、C.atomus组合出现可以预警湖泊水体富营养的发生.另外,硅藻组合还能很好地指示草型和藻型湖泊的特征,可望成为有效判识湖泊生态类型的工具.

The surface-sediment diatom assemblages of 45 lakes in the middle and lower reaches of Yangtze River region were examined for the first time. The diatom abundance distribution pattern along the gradient of total phosphorus concentration and nutrition, as well as the result from DCA using the diatoms data, indicated that the diatom assemblages were responsed towards the changes of lake nutrition states. The assemblage dominated by multi-ecotypes mainly with epiphytic, facultative planktonic, planktonic and epilithic taxa was replaced rapidly by nutrient tolerant planktonic taxa when the lake romes close to be eutropicated. Consequently it is proposed that the occurrence of the assemblages combined with the taxa of the genera Cyclostephanos, Stephanodiscus and Cy-clotella meneghiniana, C. atomus could be an alert to the lake eutropication. Moreover,the diatom assemblages perfectly denoted the characters of the macrophyte-dominant lakes and the algal-dominant lakes, and were likely to be an effective tool for judging the ecological type of lakes.