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The inland water fishes of Africa

 | 
Didier Paugy
, 
Christian Levêque
, 
Olga Otero

Fish communities in small aquatic ecosystems: caves, gueltas, crater and salt lakes

Didier Paugy e Christian Levêque

Abstract

Small aquatic ecosystems generally have several and biological characteristics. Except for their size, they time, extreme ecosystems. For example, soda lakes have similar physical are, most of the very high salinity and/or alkalinity; crater lakes are deep with a low level of oxygen in the deep layers of the water; in gueltas and chotts, the water is perennial in only a few and the temperature is high; in caves, organisms live in permanent darkness. In relation with these severe conditions, fish have developed physiological and behavioural adaptations that allow them to survive and perpetuate. Thus, specific and usually endemic species inhabit these environments. In some cases, small species flocks exist, as can be observed in the Great Lakes of East Africa. Finally, most of these environments are vulnerable to even minor disturbances. Continued vigilance, protective measures and conservation recommendations must be a high priority to protect them from actual or potential local threats.

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Estratto del testo

Strictly speaking, the crater lakes and the graben/horst lakes are different, while they both owe their formation to tectonic events.

A crater lake is a lake that formed in a volcanic crater or a caldera. In Africa, most of the crater lakes are located in dormant or extinct volcanoes, and tend to be freshwater. The water clarity in such lakes can be exceptional due to the lack of inflowing streams and sediment. Crater lakes are well represented in tropical Africa, especially in the Guinean rainforest zone of Cameroon, where there may be 36 or more (McGregor Reid & Gibson, 2011). There are also crater lakes in Eastern Africa, mainly high-mountain crater lakes in Ethiopia (Degefu et al., 2014), but the natural fish richness is generally very low or non-existent.

A graben is the result of a block of land being downthrown, producing a valley with a distinct scarp on each side. Grabens often occur side-by-side with horsts. Horst and graben structures are indicative of tensional forces and ...

Autori

Research director at IRD. He has published numerous works on the systematics, distribution, and ecology of West African fresh water fishes, and expanded the collections of the MNHN in Paris.

Research director at IRD. He has published numerous works on the systematics, distribution, and ecology of West African fresh water fishes, and expanded the collections of the MNHN in Paris.

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