Lake Natron Basin Wetland of International Importance (Ramsar Convention)

Description

Lake Natron is a salt lake located in northern Tanzania, close to the Kenyan border, in the eastern branch of Africa's Great Rift Valley. The lake is fed by the Ewaso Ng'iro River but also by mineral-rich hot springs and is quite shallow, less than three meters (10 feet) deep, and varies in width depending on its water level, which changes due to high levels of evaporation, leaving high levels of salt and other minerals. The surrounding country is dry and receives irregular rainfall. Temperatures in the lake 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).

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 also often colored red or pink by the salt-loving microorganisms that live there.

Salt marshes and freshwater wetlands around the edges of the lake do support a variety of plants.

The high temperature (up to 41°C) and the high and very variable salt content of the lake does not support most wildlife. However it is an important habitat for flamingos and is home to endemic algae, invertebrates and even fish that can survive in the salty water.

The lake is the only regular breeding area in East Africa for the 2.5 million endangered Lesser Flamingoes. As salinity increases, so do the number of cyanobacteria, and the lake can support more nests. These flamingoes, the largest flock in East Africa, gather along saline lakes in the region, where they feed on Spirulina (a blue-green algae with red pigments). Lake Natron is a safe breeding location for Lesser Flamingoes, because its caustic environment is a barrier against predators trying to reach their nests. Greater Flamingo also breed on the mud flats.

Even more amazing than the ability of the flamingoes to live in these conditions is the fact that two endemic fish species, the alkaline tilapias (Alcolapia latilabris and A. ndalalani; A. alcalica is also present in the lake, but not endemic), thrive in the waters at the edges of the hot spring inlets.

The area around the salt lake is not inhabited but there is some herding and some seasonal cultivation. Threats to the salinity balance from increased fresh water influxes will come from more projected logging in Natron watersheds and a planned hydroelectric power plant on the Ewaso Ng'iro across the border in Kenya. 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. There is no formal protection.

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.

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 more than 50 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, Conservation Programme Manager at BirdLife International's Africa Secretariat.

As per communication as on June 2008 Tata Chemicals shall not proceed with the Natron Project and further re-examination of this project will be subject to the Ramsar Wetlands plan which is currently under preparation.

Because of its unique biodiversity, Tanzania named the Lake Natron Basin to the Ramsar List of Wetlands of International Importance on July 4, 2001. The lake is also the World Wildlife Fund East African halophytics ecoregion.

There are a number of campgrounds near the lake, which is also the base for climbing Ol Doinyo Lengai