Effects of ammonia and substrate on the community composition of the epiphytic algae

In order to understand epiphytic algae community succession in the eutrophication process,the community compositions of epiphytic algaes were investigated by using macroscopic counting method under the different ammonia concentrations (0. 5,1. 5,2. 5,5 and 10 mg·L-1). The results showed that with the same epiphytic algae species inoculated,the epiphytic algal community composition varied under different ammonia concentrations. The genus of Navicula (Bacillariophyta),Gomphonema(Bacillariophyta) and Chroococcus (Cyanophyta) were dominated in the low ammonia concentration,while the genus of Navicula,Gomphonema and Ankistrodesmus(Chlorophyta) were dominated in the high ammonia concentration. At the same ammonia concentration,the abundance of dominant epiphytic algae genus was determined by the characteristic of substrates. For instance,the abundance of dominant genus on the glass slide was less than that on the Potamogeton crispus. However,the substrate could affect both the abundance and the species composition of the dominant epiphytic algae genus under high ammonia concentration. For instance,the relative abundance of the Stigeoclonium on the glass slide(65%) was much higher than that on the Potamogeton crispus(1%). It was indicated that the community composition of the epiphytic algae could be effected by both the ammonia and the substrate.