Lake withdrawal reveals giant microbialites

ISTANBUL

The loss of water due to global climate change in Lake Van, the world’s largest soda lake, has caused the emergence of “the world’s biggest microbialites” at the bottom of the water.

Only a small part of which was visible in the past years, microbialites were now completely revealed due to the receding waters.

Noting that Lake Van has a surface area of 3,710 square kilometers, Mustafa Akkuş, an assistant professor from Van Yüzüncü Yıl University, said, “[The lake] also has an extreme water quality. In other words, it is a very special ecosystem as there are sedimentary structures called microbialites formed at the base of this special ecosystem.”

“There is a calcium-rich freshwater outflow from the lake floor. The calcium in the fresh water and the soda bicarbonate in the lake combine and begin to precipitate, which causes the cyanobacteria and algae to become active and form gigantic tree-like structures on the lake floor,” he explained.

Microbialites in Lake Van are different from those in other parts of the world, Akkuş said. “Lake Van’s are the largest. While those in other lakes are 5-10 meters, those here reach up to 30-40 meters.”

In the basin of the lake overlooking the eastern province of Bitlis’ Adilcevaz district, huge tower-like alkaline microbialites of 40 meters in height have been discovered before.

Lake Van, the country’s largest, covers an area of one-third of the Marmara Sea. The water level in the lake, which has been experiencing the driest period in recent years, has decreased disturbingly.

While several major lakes in Central Anatolia are also facing an existential crisis due to global warming, the shoreline of Lake Van has begun a steady retreat, and replenishing precipitation seems to no longer maintain the basin’s water levels.

The lake earned Blue Flag status on July 4, 2018, after meeting the criteria of the eco-label awarded by the Foundation for Environmental Education (FEE), including water quality, environmental education and information, environmental management and safety.