An integrated analysis of dynamic characteristics of harmful algal bloom in fresh water in China

Eutrophication and harmful algal bloom(HAB) is a global issue.Fresh water in reservoirs and lakes in China has experienced critical eutrophication due to human activities and global warming.To indentify the HAB characteristics,dynamics and potential causes,an integrated analysis was conducted using a comprehensive database of reported HAB events.The results showed that occurrence of HAB in China expanded both spatially and temporally during 1985-2009.The underestimated HAB occurrence increased from 1-2 to about 10 times each year from 1980s to 2000s.HAB events mostly occurred in populated area(i.e.lakes and reservoirs in lower Yangtze River and coastal region) where great nutrients were loaded.Interactive effect of human activities(e.g.,fertilizer application,animal feeding,hydropower station construction) and climate warming has substantially resulted in change of hydrogeochemical conditions(nutrient enrichment,N:P ratio decline),which resulted in the risk of HAB forming in reservoirs and lakes.The control of eutrophication will likely require integrated basin-marine reductions in both N and P,and interdisciplinary understanding of the key physical,chemical and biological factors that determine the HAB process in target aquatic systems.