The influence of habitat structure and flow permanence on macroinvertebrate assemblages in temporary rivers in northwestern Zimbabwe |
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Authors: | Albert Chakona Crispen Phiri Christopher H D Magadza Luc Brendonck |
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Institution: | (1) University Lake Kariba Research Station, PO Box 48, Kariba, Zimbabwe;(2) University of Zimbabwe, PO Box MP167, Mt Pleasant, Harare, Zimbabwe;(3) Laboratory of Aquatic Ecology, KU Leuven, Deberiotstraat 32, Leuven, 3000, Belgium |
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Abstract: | Temporary rivers within the Nyaodza-Gachegache subcatchment in northwestern Zimbabwe were investigated to examine the role
of flow permanence and habitat structure on macroinvertebrate community composition. Macroinvertebrate communities of intermittent
and ephemeral rivers displayed significant differences in the number of taxa, macroinvertebrate abundance, Shannon and Simpson
diversity indices and in size class structure. Intermittent sites were characterised by higher numbers of taxa, diversity
and Ephemeroptera and Trichoptera richness compared to ephemeral sites. The fauna of ephemeral sites was dominated by a single
taxon (Afrobaetodes) (Ephemeroptera, Baetidae) whilst larger sized taxa (e.g. Elassoneuria (Ephemeroptera, Oligoneuriidae), Dicentroptilum (Ephemeroptera, Baetidae), Aethaloptera (Trichoptera, Hydropsychidae), Pseudagrion (Odonata, Coenagrionidae) and Tholymis (Odonata, Libellulidae) were exclusively restricted to intermittent sites. Clear differences were observed between sand,
gravel, cobble and vegetation habitats. Vegetation and cobbles supported distinct communities, with some taxa exclusively
restricted either to vegetation (e.g. Pseudagrion, Leptocerina (Trichoptera, Leptoceridae), Cloeon (Ephemeroptera, Baetidae), Afronurus (Ephemeroptera, Heptageniidae) and Povilla (Ephemeroptera, Polymitarcidae) or cobble (e.g. Aethaloptera and Dicentroptilum) habitats. In terms of ensuring optimum diversity within the subcatchment, we consider conservation of critical habitats
(cobbles and vegetation) and maintenance of natural flows as the appropriate management actions.
Handling editor: D. Dudgeon |
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Keywords: | Dry-land rivers Flow regime Macroinvertebrates Management |
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