Ecological Study Of The Periphyton Of Lake Erhai

Periphyton,the algae grown on all kinds of substrata in water, is the important primary producer in aquatic environment,and plays important roles in aquatic ecosystem.In order to evaluate the function of periphyton in the littoral zone of Lake Erhai,the epiphyte community in watershed of Lake Erhai was investigated,and the effects of some environment variables impact chl a, dry weight and ash-free dry weight and biodiversity.The investigation show that the standing crop of Erhai Lake is higher than that of Xihu Lake and Cibihu Lake.The chl a of Erhai Lake is significantly higher than that of Xihu Lake and Cibihu Lake.The dominant species of Erhai Lake are Cladophora glomerata,Diatoma vulgare and Psephonema aenigmat,compared with the Navicula spp, P.aenigmat in Xihu Lake and N.spp,Cymbella spp, Fragilaria spp. in Cibihu Lake Cibihu,respectively. The chl b of Erhai Lake is generally preceded,and the ratio of chl b/c is significantly greater than that of Cibihu Lake(P<0.05),which show that Erhai Lake has more proportion of green algal than the other two Lakes.Otherwise,the ratio of chl c/a appear to the sites of Xihu Lake, Cibihu Lake subsequently,which proclaim that the relative amount of diatom is Xihu Lake>Cibihu Lake>Erhai Lake.The same answer is obtained in algal cell count result,which display Cladophora glomerata was more in Erhai Lake,on the other hand,more Cyclotella spp,Navicula spp, Cymbella spp were found in Xihu Lake and Cibihu Lake. CCA analyses were conducted to evaluate the relationship between the abundance of periphyton and the environment factors,which showed that TP concentration in water were the main factors affecting the species distribution in Erhai drainage area.The effects of waves,depths,types of substrata,roughness and water quality impacted on the biomass and biodiversity of periphyton attached on artificial substrata reveal that the waves had bigger influence. The reduction of biodiversity due to waves is significantly(P<0.05),and lower the biomass(P<0.05), simultaneity.The reason may be that only some kinds of periphyton which had powerful capacity of attachment can grow on the substrata,thereby the biodiversity of algae reduced. Types of substrata has little effects on the biomass of periphyton,but roughness can elevate the biodiversity(P<0.01). The biggest biomass turn up on the depths of 0 m and 0.5m,moreover,the biodiversity is preceded 1.5m depth,significantly(P＜0.01).So 0m-0.5m is the most optimum depth for periphyton.P is beneficial to the growth of periphyton, thus the biomass and biodiversity in Gusheng area contain more P concentration in the water is much higher than that in Xiahe area(P<0.01).