New images show an algal bloom in the Caspian sea that’s so big it can be seen from space. The recently released images taken by South Korea’s Kompsat-2 satellite in 2012 show green waters in a shallow northern section of the sea, known as the Vogel Delta, which indicate an algal bloom is happening there. According to the European Space Agency, high levels of phosphorus, such as those found in fertilizers, detergents and unfiltered sewage, cause algal blooms such as this. Once they take hold, algal blooms deplete oxygen levels and can choke our other important forms of life such as the sturgeon that live in the Caspian Sea.

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The area where the algal bloom is happening lies close to an area of Kazakhstan that’s rich in minerals and fossil-fuel reserves, often called the country’s ‘treasure’ peninsula. Earth Snapshot notes that industrial and agricultural modification of the area has resulted in massive wetland loss, while discharges of large amounts of industrial waste and sediment into the relatively shallow section of sea help the algal blooms flourish.

Related: NASA team discovers massive algal bloom under Arctic ice

With just over 143,000 square miles of surface area, the Caspian Sea is the largest land-locked body of water on Earth–larger than Germany. The Caspian Sea is no stranger to algal blooms such as this; a similar bloom happened in 2005 and impacted more than 7,700 square miles.

Via ESA

Images via ESA and eutrophication&hypoxia, Flickr Creative Commons