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).
Flora
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.
Fauna
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 an endemic species of fish, the
alkaline
tilapia (
Oreochromis alcalicus), thrives
in the waters at the edges of the hot spring inlets.
Threats and preservation
The area around the salt lake is not inhabitated 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 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.
The lake
is also the World Wildlife Fund
East African
halophytics
ecoregion.
Visiting the area
There are
a number of campgrounds near the lake, which is also the base for
climbing Ol Doinyo
Lengai
See also
References
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