Invasive vertebrates of South Africa

Abstract

From an economic point of view, agriculture and tourism, along with mining production, are South Africa’s largest economic sectors. However, South Africa is becoming increasingly reliant on ecotourism as an economic growth sector, which is, in turn, reliant on maintaining the productive and aesthetic value of South Africa’s protected areas and interstitial landscapes. This, together with other important human bene¢ts gained from maintaining biodiversity (e.g., ecological services, harvesting of wild species, aesthetically and culturally), suggests that key role players responsible for policy making in the country are faced with particular challenges where conservation and economic development needs are in con®ict (see e.g., reference1). Yet, at the same time, vertebrate introductions that result in invasions have the potential to alter these valuable environments. For example, considering the anthropogenic movement of ungulate species (both alien and extralimital) in South Africa, known for their recreation and food source value, Spear and Chown2 have shown that their movement has led to a 1.34% increase in the similarity of ungulate assemblages at a quarter-degree grid-cell resolution. At least 21 invasive ¢sh species are present in South Africa. While the impact of these species on aquatic ecosystems has been profound, resulting in the extirpation or localized extinction of a number of indigenous ¢shes, amphibians, and invertebrates, alien invasive ¢shes drive a large recreational ¢shery that has signi¢cant economic value. As a result of these positive economic contributions of certain invasive vertebrates, the implementation of legislation governing the importation and movement of both alien and extralimital species in South Africa will require careful consideration of the trade-offs between economic gain and biodiversity loss.