Lake

Lake Tanganyika :

[Satellite Images] [Large Scale Maps]

Lake Tanganyika is one of the rift lakes of Africa and is confined by four Countries :

North-East by Burundi

West by Democratic Republic of Congo

South by Zambia

South-East by Tanzania

First made known to Europeans in mid 1800's by English explorers Richard Burton and John Speke.
Area is 34,000 sq. Km and is the seventh largest lake in the world.
Longest freshwater lake on Earth. Length of 650 km and a maximum width of 80 km.
Second deepest lake on Earth. Maximum depth of 1433m, which is 642m below seal level.
The bottom (not the shores) is covered by a thick layer of sediment, several hundred metres thick.
Almost all life in the lake is in the upper 200 m of the water column. No mixing of lower waters which remain dead - either too high in hydrogen sulphide or too low in oxygen to support life. It is suggested that this "fossil" water may be as old as 200 million years.
Temperature is a constant 26.6°C all year round.
Temperature of lower regions of the water column are only 3°C colder than the surface - an unexplained phenomenon.
Approximately 90% of annual precipitation evaporates.
Lake shores consist of alternating sandy beaches and rocky outcrops.
Water chemistry is uniform throughout the lake. The pH ranges from 8.8 to 9.3
There is virtually no plant growth.
Isolation of lake and age of waters has led to the evolution of unique fish populations. More than 350 species of fish inhabit the lake and many of them are endemic - 98% are unique to the lake.
Regarded as an evolutionary showcase due to its age and stability.
The Lake has the following habitats :

Surge habitat
Confined to the upper 3 metres of the water column. Main characteristics are relative abundance of food and turbulent water. The width of this habitat varies greatly and is dependent on the inclination of the coastline. Water is well oxygenated. A slightly higher pH range is observed due to the rapid removal of CO2 due to the turbulence. Temperature is constant, even in the extreme shallows as a result of the continuous mixing of these upper layers.

Shallow precipitous rocky habitat
Characterised by the piling of rocks forming complicated network of caves. Rocks are free of sediment and the algae flourishes. This abundance of food and competition for living space means that the fish species here are strong and aggressive in order to secure a territory. J. marlieri, J. transcriptus and J. dickfeldi are found here.

Deep rocky habitat
Characterised by the sediment covered rocks and small patches of mud and sand between the rocks. This habitat is deeper than 20 metres and light is subdued. Algae growing on the rocks is significantly reduced and tends to be brown in colour.

Intermediate habitat
Characterised by a sandy bottom with numerous rocks which provide shelter for this species rich environment. There is a gradual inclination of the bottom. A thin layer of sand covers the biocover. Most heavily populated between 5 and 40 metres. This habitat harbours the most species rich communities of the lake. J. regani and J. ornatus are found here.

Shallow sediment-rich habitat
Characterised as a mixture of sand and mud and rocks on a gradually shelving shore. Typically the habitat is no deeper than 3 metres. These habitats are commonly near the mouths of rivers and consequently there is a muddy sediment covering. Water plants are found here. Algae feeding cichlids are not common here.

The predominant fish life in the lake is cichlids. The main reasons are :

secondary fish - highly tolerant towards dissolved salts.

closed swim bladder - filled by a gland that extracts oxygen from the blood so there is no need to reach the surface.

mouth brooding and parental care of the young.