Chembe beach viewed from hills at Otter Point
Photograph Provided by by G.F.Turner |
Thumbi West Island viewed from Chembe Beach
Photograph Provided by by G.F.Turner |
| Photographs taken from Pages by G.F.Turner, Professor of Evolutionary Biology and Biodiversity, Dept of Biological Sciences University of Hull, UK- copyright unknown |
Malawi, a deep lake in south-east Africa, is a critical resource not only to the people of Tanzania, Mozambique and Malawi who rely on it for food, drinking water, irrigation and hydroelectricity but also as one of the most biologically diverse ecosystems on the planet. It contains more species of fish than any other lake in the world, with 300 already identified and double that number estimated more than in all of North America. The fact that most of these species are found nowhere else makes the lake a unique and irreplaceable scientific resource.
Lake Malawi is one of the oldest freshwater lakes in the world--the descendant of a body of water that has been continuously present in the Malawi rift valley for nearly a million years. Because they have had such a long time to evolve and diversify, virtually all of the hundreds of species in Lake Malawi are from the same flock in that they have a common ancestor that arrived there long ago from an inflowing river. Only lakes Baikal and Tanganyika, which also have species flocks, are older. Although its great age partially explains Lake Malawi's rich biodiversity, the question of why there are so many species in a single lake continues to draw scientists from all over the world to this unique resource. Source : The Green LaneTM, Environment Canada's World Wide Web site.
Lake Malawi (Nyasa) is the most southerly of the great African Rift Valley lakes. It is about 560 km long and has a greatest width of about 75 km. In contrast with Lake Tanganyika, it consists of a single basin with greatest depth of about 706 m near the western shore about 45 km north of Nkhata Bay. It lies between 9:30-and 14:30S at an altitude of about 500 m in a tropical climate. However it lies far enough south of the equator to experience marked seasonal variations in wind, temperature and precipitation.
The lake occupies part of the southern end of the Rift Valley system and is to a large extent delimited by faults, particularly to the north and on the eastern coast. In these areas the shores are steep and depths in excess of 200 m are found close inshore. At the southern extremity and along the southern half of the west coast the shoreline is more gently shelving. From here the bottom rises gradually to north and south and, except for a ridge some 20 m high at 10:25S, there is no trace of separate basins as in Lake Tanganyika.
In further contrast to Lake Tanganyika, where a depth of 200 m is found within 20 km of the southern extremity of the lake, in Lake Malawi such a depth is not encountered within 110 km of the southern end. Source : World Lakes Database. |
|
|
African Rifts /information.html |
|
