Why is there a large area of dead fish in Shangtang River in Hangzhou?

On the morning of July 4th, the sun was shining in Hangzhou, but the Shangtang River was stinking. These dead fish are mainly concentrated on the water surface at the junction of Haining Changshu Community and Xucun, Henan Garden Street, Shangtang.

High temperature and hypoxia or main cause

Residents living by the river said that they saw a lot of fish floating on the water last Saturday, but they didn't pay special attention. Unexpectedly, two days later, I saw a large piece of dead fish floating on the river, and the smell of dead fish rotting made people hide their noses. Although there have been dead fish before, there are only a few, never seen such a large area.

What caused such a large area of dead fish?

The staff of the fishery administration department in Yuhang District analyzed that the low temperature and heavy rain in the past few days led to lack of oxygen on the water surface. "Under the influence of heavy rain, the organic matter in the bottom mud turns up, which leads to the fermentation of the river bed mud and absorbs a lot of dissolved oxygen, which reduces the oxygen content of the originally anoxic water body and easily leads to the death of fish.

Another possible reason is that the weather is too hot, the water level drops and the water quality is not as good as before. "

Residents along the river have speculated about the cause of death of fish. Some people think that the river is polluted, others think that there are too many algae in the water and the water is eutrophic.