Algae pollution is a major threat to China's freshwater supply and ecosystem. Over the years, technology has become more effective at curbing algae blooms, but that will not be enough to cure the problem, ecologists said.

"The key to stopping algae pollution is controlling the sources of nutrients washing into Taihu," said Qin Boqiang, director of the Taihu Laboratory for Lake Ecosystem Research at the Chinese Academy of Sciences.

Zhu Guangwei, a biochemist at CAS's Nanjing Institute of Geography and Limnology, said more than 100 canals feed into the lake - one of China's largest freshwater bodies - which makes it extremely difficult to identify pollution sources.