Water beetles associated with reservoirs on Table Mountain, Cape Town: implications for conservation

Abstract

Table Mountain maintained internationally high global conservation priority with respect to the aquatic Coleoptera. The study site displayed an overall 77% endemism with 65% of species provisionally of high IUCN international conservation status. Reservoirs were shown to have a dramatic negative impact on the endemic and endangered water beetles of Table Mountain. This comprised of an overall species loss of 73%, all endemics, and a 64% loss of high conservation status species in the Hydraenidae, Dryopidae and Elmidae. Further hydrological alteration in the region was not recommended and the necessary inclusion of water beetles in future EIA assessments stipulated. The necessity for bioinventory methodology in addition to standard netting methodology was conclusively illustrated. A Balanced Scorecard approach to conservation decisions based on species level data including appropriate bioinventory survey methodology, recent survey data, IUCN status, and levels of endemism was proposed. The differentiation of species communities with altitude produced a division between upland and lowland communities on Table Mountain. Distinct differences between the reservoir impacted and natural upland water beetle communities were demonstrated.