Chinese sea is covered with algae covering nearly 29,000 km2

China's Yellow Sea is suffering from invasive algae at an extremely fast speed, with nearly 29,000 square kilometers covered by algae, according to Chinese officials on July 4.

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The pictures show the swimmers playing and playing in the blue wave in Qingdao - not the usual blue, but the green of the algae. Meanwhile, bulldozers operate continuously to bring tons of algae to destruction.

Algae covers a public bathing area in Qingdao, Shandong Province - (Photo: AFP)

Photo taken from above shows a large area of ​​Qingdao sea covered by algae - (Photo: AFP)

On its website, the China Ocean Administration said the algae has a scientific name, Enteromorpha prolifera . It appeared a week ago and now spreads to an area of ​​28,900 square kilometers.

The biggest algae occurrence in the past was in 2008, when they spread to a sea of ​​13,000 square kilometers.

Xinhua quoted Qingdao officials as saying it had removed about 7,335 tons of algae.

The appearance of algae is often caused by the abundance of nutrients in water, especially phosphorus.

"There must be something that makes the marine environment change, but we do not have clear scientific evidence for this yet," said China Daily, quoted by Chinese journalist Bao Xianwen .

The algae are not toxic and do not harm water quality. However, their presence leads to an imbalance in the ecosystem by consuming large amounts of oxygen and producing hydrogen sulphide.