Blue-green algae have spread rapidly in Xingyun Lake near Kunming, the capital of Yunnan.

Early this month, experts from the Aquatic Organism Institute of the Chinese Academy of Sciences gathered to debate how to keep the algae under control, but the final solution is still under discussion, according to the environmental protection authorities in the city of Yuxi.

Some experts suggested raising fish and clams that can feed on the weed. Others suggested growing aquatic plants or using a microbial pesticide.

However, the temperature, rainfall and other local climatic and geographic conditions will have a direct bearing on the suitability of any proposed solution, said a bureau official who declined to be identified.

Scientists describe blue-green algae as an ecological cancer for water. The algae reproduce rapidly during hot weather in water that contains too many nutrients and they can severely pollute the water.

Blue-green algae are also known scientifically as cyanobacteria.

The algae sometimes make water appear green in colour and sometimes form a blue-green scum on the surface of the water. They also produce a foul smell. The algae are toxic and the toxins may kill pets and other animals and even be poisonous to humans.

According to experts, a combination of drought, high summer temperatures, reduced water flow and increased turbidity have all played their part in creating conditions for algae growth in Xingyun Lake.

(China Daily June 21, 2002)