Phytoplankton Assemblages And Their Response To The Macrophyte Restoration In Typical Urban Lakes Of Guangdong, China

The paper reportes the phytoplankton assemblages of the main urban lakes in Guangdong province, and evaluates the trophic state and effects of ecological restoration of the lakes by analyzing species composition,cells density and biomass of phytoplankton. The results showe that Lu Lake, Dongshan Lake, Xing Lake, Hong Lake, Liwan Lake, Liuhua Lake, Yuanyang Lake, E Lake, Xianyi Lake and Dong Lake all have been polluted, and they all have became eutrophicated. The cells density of the lakes arranged between 2041.1×10~4cells/L to 7356.5×10~4cells/L, and all of them were beyond the eutrophication standard of 10~6cells/L; The biomass of phytoplankton were also very high, except Yuanyang Lake which had the value of 1.95mg/L, and were all beyond the eutrophication standard of 5mg/L and the maximum vqlue of 12.39mg/L was oberserved in Xin Lake. Meanwhile, the phytoplankton assemblages were dominated by Merismopedia elegans and M. granulata.Ecological restoration is an important way in management of eutrophic shallow lakes. Using Huizhou West Lake as a example, the paper studied the current trophic state and ecolosystem response of the lake to macrophyte restoration by comparing the restorated and un-restorated lake area.The results showed that after the sewage diversion and sediment dredging, the water qulity of the Huizhou West Lake had no significant improvement. The water transparency was only 31cm, the nitrogen and phosphorus content were still high, but the average phytoplankton cells density of the lake was 5958.63 × 10~4Cells/L, which was about 1/3 of Hangzhou West Lake. Meanwhile, the water bloom was seldom occurred in this lake which may be attributed to the low illumination due to high sediment resuspension caused by fish and boat activity in this lake. After the ecological restoration, the water quality was significantly improved. Comparing with the Ping Lake (un-restorated area), the water tranparency was increased greatly, the nitrogen and phosphorus content had a significant reduction in restorated lake area.. Tthe average cells density and biomass of restortated area were 71.22 × 10~4 cells/L...