As summer rolls around, the coastal city of Qingdao in east China's Shandong Province is again facing an annual invasion of green algae, or enteromorpha prolifera that transforms its coastline into a large swathe of green. /VCG Photo

The algae bloom washed up on the shores covered about 477 square kilometers of land in the Yellow Sea and Bohai Sea area as of June 27, Xinhua said. /VCG Photo

While the algae is not known to be harmful to people, it consumes large amounts of oxygen that can cause extensive damage to marine life. /VCG Photo

Ever since the first outbreak in 2007, the region has suffered algae attacks every summer, with different explanations given, such as climate change, industrial pollution and seaweed farming. /VCG Photo