ecological engineering 35 ( 2 0 0 9 ) 1637–1645 available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/ecoleng Water quality improvement and phytoplankton response in the drinking water source in Meiliang Bay of Lake Taihu, China Fei-Zhou Chen a,∗ , Xiao-Lan Song a,b , Yao-Hui Hu a , Zheng-Wen Liu a , Bo-Qiang Qin a a State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Beijing East Road 73, Nanjing 210008, China b Graduate School of Chinese Academy of Sciences, Beijing 100039, China article info Article history: Received 7 March 2007 Received in revised form 24 December 2007 Accepted 1 January 2008 Keywords: Lake Taihu Drinking water source Ecological restoration External loading Microcystis abstract Water quality experienced changes throughout the 3-year ecological engineering experi- ment in the drinking water source in Meiliang Bay of Lake Taihu. Average concentrations of TN, TP, NH 4 + , BOD 5 and transparency in the drinking water source during the period of July–December 2005 were 1.85, 0.13, 0.23, 3.03 mg L -1 and 27.5cm, respectively, decreas- ing by 47.9%, 21.2%, 83.3%, 54.4% and 24.2%, compared to concentrations from the same period in 2003. Concentrations of chlorophyll a and COD were 89.9 gL -1 and 6.45 mg L -1 , increasing by 27.9% and 17.7%, compared to the values in 2003. Cyanobacteria (mainly Micro- cystis) dominated the phytoplankton community in the ecological engineering area during July–December 2005. Densities of cyanobacteria and Microcystis were higher in 2005 than in 2004 and higher inside the engineering area than outside. Density percentages of cyanobac- teria and Microcystis to total algae were above 90% and 60% during the bloom period. Average density of flagellate algae was higher during July–December 2005 than in 2004. Changes in water quality in the engineering area resulted mainly from the weakening of waves, decrease in concentrations of suspended solids, and assimilation of mass algae and periphytons. In spite of initial improvement of water quality, cyanobacterial bloom still determined the phy- toplankton dynamics and variations. Additionally, nutrient concentration still remained at a high level without control of external loading. Therefore, a more holistic approach and long-term management should be adopted in Lake Taihu. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Since the 1980s, China has faced a great water quality prob- lem. Many lakes, especially urban lakes, have deteriorated because of eutrophication due to excessive nitrogen, phos- phorus, organic matter and other pollutants. Since that time, national and regional governments have been making efforts ∗ Corresponding author. Tel.: +86 25 86882106; fax: +86 25 57714759. E-mail address: feizhch@niglas.ac.cn (F.-Z. Chen). in lake restoration. Governments and many researchers have adopted many measures to restore and manage the different kinds of lakes. Several lake restoration projects have been car- ried out in Lake Taihu (Pu et al., 1993), Lake Dianchi (Li et al., 2005), Lake Wuli (Chen et al., 2006), Lake Mochou (Pu et al., 2001), and other small lakes (Tu et al., 2004) in China. Lake restoration has included the restoration of water body, littoral zone, and land. Owing to the difficulty of 0925-8574/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.ecoleng.2008.01.001