Controlling cyanobacterial blooms by managing nutrient ratio and limitation in a large hypereutrophic lake： Lake Taihu, China

• Published in: 环境科学学报：英文版 no. 1; pp. 80 - 86
• Main Author: Jianrong Ma Boqiang Qin Pan Wu Jian Zhou Cheng Niu Jianming Deng Hailin Niu
• Format: Journal Article
• Language: English
• Published: 2015
• Subjects: 太湖; 富营养化湖泊; 控制; 浮游植物生物量; 管理目标; 营养比例; 营养素; 蓝藻水华
• ISSN: 1001-0742; 1878-7320

Excessive nitrogen（N） and phosphorus（P） loading of aquatic ecosystems is a leading cause of eutrophication and harmful algal blooms worldwide, and reducing nutrient levels in water has been a primary management objective. To provide a rational protection strategy and predict future trends of eutrophication in eutrophic lakes, we need to understand the relationships between nutrient ratios and nutrient limitations. We conducted a set of outdoor bioassays at the shore of Lake Taihu. It showed that N only additions induced phytoplankton growth but adding only P did not. Combined N plus P additions promoted higher phytoplankton biomass than N only additions, which suggested that both N and P were deficient for maximum phytoplankton growth in this lake（TN：TP = 18.9）. When nutrients are present at less than 7.75–13.95 mg/L TN and 0.41–0.74 mg/L TP, the deficiency of either N or P or both limits the growth of phytoplankton. N limitation then takes place when the TN：TP ratio is less than 21.5–24.7（TDN：TDP was 34.2–44.3）, and P limitation occurs above this. Therefore, according to this ratio, controlling N when N limitation exists and controlling P when P deficiency is present will prevent algal blooms effectively in the short term. But for the long term, a persistent dual nutrient（N and P） management strategy is necessary.