Meet Natron – the red lake in Tanzania that turns animals to ‘stone’

Lake Natron lies along the East African Rift System, a divergent tectonic plate boundary that is slowly splitting the African Plate apart.

Located in northern Tanzania, Lake Natron is like a caustic soda bath due to its volcanic geology, maintaining a water pH of around 10.5 nearly as caustic as ammonia solution. As a result, animals that die on its shores become preserved as calcified mummies.

This unique geology means that Lake Natron was formed by volcanic processes that produce large quantities of sodium carbonate and calcium carbonate. These salts and other minerals flow into the lake from the surrounding hills and enter the water through hot springs, according to Live Science. Since the lake has no outlet to rivers or oceans, its chemical concentration remains high throughout the year.

Few animals can survive the lake’s extreme salinity and high pH levels, and its waters can severely burn the skin and eyes of creatures that try to drink or enter it. However, some species have adapted to these harsh conditions including lesser flamingos (Phoeniconaias minor) and tilapia and thrive in and around the lake.

In fact, Lake Natron is the world’s most important breeding site for lesser flamingos. The majority of East Africa’s 1.5 to 2.5 million lesser flamingos which make up about 75% of the global population hatch in this lake, according to Tanzania’s Wildlife Management Authority. These birds have tough skin and scaly legs that protect them from chemical burns.

Besides being extremely alkaline, Lake Natron is also very shallow water temperatures can reach up to 60°C (140°F) during the hottest times of the year, according to NASA’s Earth Observatory.

The lake is about half a meter deep and 15 kilometers wide, but it shrinks or expands depending on the season. Less rainfall and river inflow during the dry season lead to its shrinkage and the reverse occurs in wetter times.

As the lake shrinks, salt-loving microorganisms multiply. Haloarchaea (salt-loving organisms without a nucleus) and cyanobacteria (blue-green algae) can turn the lake various shades of red, thanks to pigments in their cells. These same pigments give lesser flamingos their distinctive pink hue, as the birds feed almost exclusively on the blue-green algae, according to NASA’s Earth Observatory.

“KORÇA BOOM”