Feeding of the exotic Louisiana red swamp crayfish,Procambarus clarkii (Crustacea,Decapoda), in an African tropical lake: Lake Naivasha,Kenya |
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Authors: | Smart Andrew C. Harper David M. Malaisse François Schmitz Sophie Coley Stephanie Gouder de Beauregard Anne-Christine |
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Affiliation: | (1) Department of Biology, University of Leicester, Leicester, LE1 7RH, U.K;(2) Present address: Duchy College, Rosewarne, Camborne, TR14 0AB Cornwall, U.K;(3) National Botanic Garden of Belgium, Domaine de Bouchout, B-1860 Meise, Belgium;(4) Laboratoire d'Ecologie, FUSAGx, Passage des Déportés 2, B-5030 Gembloux, Belgium |
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Abstract: | The Louisiana red swamp crayfish, Procambarus clarkii, has had a major impact on aquatic ecosystems in Europe and America where it has been introduced for human consumption. In Lake Naivasha, where it was introduced in 1970, it is suspected of causing the complete disappearance of native floating-leaved and submerged plants by 1982 and again by 1996; recovery of submerged plants occurred in between, concurrent with a decline in P. clarkii. Examination of the feeding of P. clarkii by microscopic analysis of gut contents collected from the lake confirmed information from both its native and exotic ranges; that it is an omnivore with green plants and insects the predominant items recognised. Feeding experiments confirmed this omnivory, with a preference from herbivory over carnivory. They further showed the importance of native plants as opposed to exotic water hyacinth Eichhornia crassipes. It is concluded that P. clarkii could well have accounted for the observed elimination of native plant species in Lake Naivasha; the cyclical nature of populations of submerged plant species and of P. clarkii in inverse proportion to each other lead us to hypothesise that P. clarkii is a `keystone' species in the lake ecosystem. |
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Keywords: | submerged aquatic macrophytes omnivory freshwater crayfish |
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