Stream fish assemblage and habitat structure in a tropical African river basin (Nyagui River, Zimbabwe) |
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Authors: | Wilbert T Kadye Ngonidzashe A G Moyo |
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Institution: | Department of Biological Sciences, University of Zimbabwe, PO Box MP 167, Mount Pleasant, Harare, Zimbabwe;and Aquaculture Research Unit, University of Limpopo, Private Bag X1106, Sovenga 0727, South Africa |
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Abstract: | Few studies have been carried out on stream ecology in southern Africa although many species are endangered. This study investigated the stream fish assemblage and their habitat associations over a period of 3 months (October 2004 to January 2005), in view of the proposal to build a dam across the Nyagui River. Twenty-four fish species were collected and were separated into groups based on preferred microhabitats. The first group, dominated by Barbus paludinosus , comprised species collected from the upstream stations with slow flow, shallow depth (pools) and fine substrate type. Species associated with riffles, which included Chiloglanis neumanni , Labeobarbus marequensis and Opsaridium zambezense , comprised the second group on the downstream. The last group comprised species preferring pools with rock substrate and slow flow such as Pharyngochromis acuticeps and Pseudocranilabrus philander . The species were consistently associated with their habitat types throughout the sampling period. This relationship may be explained by the fish's morphological adaptations. Species richness increased from nine in the upstream section to twenty in the downstream section and this was related to increasing habitat complexity downstream. The construction of the Kunzvi Dam across the Nyagui River is likely to lead to loss of rheophilic species while cichlids and introduced species may increase. |
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Keywords: | conservation microhabitat ordination river species |
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