Primary Productivity Of Benthic Algae In Liangzi Lake And The Efficiency Of Water Treatment By Cladophora Oligoclona

Eutrophication phenomenon is one of the most serious problems in China and has caused deterioration of water quality. It restricts the development of economic and does the negative effect on human's life. It is important to monitor the water environment termly and to find the effective treatment measurement. This research studied the primary productivity of benthic algae in Liangzi Lake to provide basic information for the protection of the lake. We also studied the efficiency of Cladophora oligoclona in water treatment under different conditions to explore the potential value of this algae in water body protection.Beizui and Qianhaidi were the two sample stations in Liangzi Lake and water chemical index, Chl a content and the primary productivity were investigated in 7 months. The results indicated that Liangzi Lake is an oligotrophic lake and the water quality is at II~III class. The primary productivity of the benthic algae measured by CO2 assimilating rate of the communities at the two sample stations in 7 months suggested that benthic algae at the littoral zone got the higher primary productivity. The mean value at sunny day were 0.2~0.5g C/m2·d,the highest could reach 1gC/m2·d. P/R coefficient of community was about 1.0, which indicated the benthic community belonged to the stable community. The bio-index of water quality including is very useful in monitoring and assessing water body, but also need further study. Using chlorophyll a and primary productivity to monitor and assess the water environment was very useful but more further study need to be done.The removal efficiency of nitrogen and phosphorus in different lake with different trophic states by Cladophora oligoclona and the inhibition to bloom-forming algae were studied in this paper. The results indicated that for little natural water body, the removal rate of TN was 13.5% ~ 45.8%, the removal rate of NH4-N were 33.3% ~ 50.0%. For East Lake, the removal rate of TN, NH4-N, TP and SRP per day were 45.3%～59.3%, 36.1%～48.7%, 31.8～38.6% and 27.7%～ 33.6%, respectively. For Yue Lake Cladophora oligoclona could inhibit growth of Microcyatia flos-aquae. It could be concluded that Cladophora oligoclona could survive different environment with different nutrient status, and it could be useful to purify the water.