Lake Natron

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Lake Natron

Location	northern Tanzania
Coordinates	2°25′S 36°00′ECoordinates: 2°25′S 36°00′E
Lake type	saline
Basin countries	Tanzania

Southern half of Lake Natron. In the inset, numerous, near-white salt-crust "rafts" pepper the shallowest parts of the lake. In the top image, fault scarps and the Gelai Volcano can also be seen.

Lake Natron is a saline lake located in northern Tanzania, close to the Kenyan border, in Africa's Great Rift Valley. The lake is quite shallow, less than three meters (10 feet) deep, and varies in width depending on its water level.

The color of the lake is characteristic of those where very high evaporation rates occur. As water evaporates during the dry season, salinity levels increase to the point that salt-loving microorganisms begin to thrive. Salt-loving organisms include some cyanobacteria, tiny bacteria that grow in water and make their own food with photosynthesis as plants do. The red pigment in the cyanobacteria produces the deep reds of the open water of the lake, and orange colors of the shallow parts of the lake.

The alkali salt crust on the surface of the lake is often colored red or pink by the salt-loving microorganisms that live there. And the lake is the only breeding area for the 2.5 million endangered Lesser Flamingoes that live in the valley. As salinity increases, so do the number of cyanobacteria, and the lake can support more nests. These flamingoes flock along saline lakes in the region, where they feed on Spirulina (a blue-green algae with red pigments). Lake Natron is the only breeding location for Lesser Flamingoes because its caustic environment is a barrier against predators trying to reach their nests. The temperatures in the mud can reach 50 degrees Celsius (120 degrees Fahrenheit), and depending on rainfall, the alkalinity can reach a pH of 9 to 10.5 (almost as alkaline as ammonia). Even more amazing than the ability of the flamingoes to live in these conditions is the fact that an endemic species of fish, the alkaline tilapia (Oreochromis alcalica), thrives in the waters at the edges of the hot spring inlets.

Threats to the salinity balance from increased fresh water influxes will come from projected logging in Natron watersheds and a planned hydroelectric power plant. Although development plans include construction of a dike at the north end of the lake to contain the fresh water, the threat of dilution to this breeding ground may still be serious.

A new threat to Lake Natron is the proposed development of a soda ash plant on its shores. The plant would pump water from the lake and extract the sodium carbonate to convert to washing powder for export. Accompanying the plant would be housing for over 1000 workers, and a coal fired power station to provide energy for the plant complex. In addition, there is a possibility the developers may introduce a hybrid brine shrimp to increase the efficiency of extraction.

Mount Lengai seen from Lake Natron

According to Chris Magin, the RSPB's international officer for Africa 'The chance of the lesser flamingoes continuing to breed in the face of such mayhem are next to zero. This development will leave lesser flamingoes in East Africa facing extinction'. Currently a group of 20 East African conservation and environmental institutions are running a world wide campaign to stop the planned construction of the soda ash factory by Tata Chemicals Ltd of Mumbai, India and National Development Corporation of Tanzania. The group working under the umbrella name Lake Natron Consultative Group is being co-ordinated by Ken Mwathe, Head of Ecology at African Conservation Centre.

Because of its unique biodiversity, Tanzania named the Lake Natron Basin to the Ramsar List of Wetlands of International Importance on July 4, 2001.