The conservation value of artificial ponds in the Western Cape Province for aquatic beetles and bugs

[摘要] Freshwater insect species and their host ecosystems are widely threatened,particularly within agricultural and urban landscapes of Mediterranean areas,including that of the Western Cape Province, South Africa. The study heredetermined the biodiversity value of nineteen artificial ponds (temporary andpermanent) and two river margin sites in the Cape Floristic Region (CFR). The aimwas to determine aquatic beetle and bug abundance and species richness in theseponds, a topic which has been hardly explored in South Africa. Sites were sampledfrom September 2005 to September 2006. A total of 18 677 aquatic beetle and bugindividuals were sampled, representing 43 genera (28 beetle and 15 bug genera), 64species (44 aquatic beetle and 20 bug species). Different pond types had distinctspecies assemblages. The associated physico-chemical characteristics of these siteswere also investigated. The key environmental variable affecting aquatic beetle andbug distribution was naturalness (no human and environmental impact onwaterbody). The results showed that the most important determinant of aquaticbeetle and bug species richness across all sites was emergent macrophytes, such asTypha capensis and Persicaria decipiens. Artificial ponds in the CFR clearly increasethe area of occupancy for insects, and therefore play a major role in conservingthem. This is especially so when the ponds are at moderate temperatures (i.e. 19ºC). Although all ponds contributed to the aquatic beetle and bug diversity in theregion, they differed in relative value, depending on the combination of environmentalvariables affecting each pond.

[发布机构] Stellenbosch University