Invasive Alien Aquatic Plants in South African Freshwater Ecosystems

South Africa has a long history of managing the establishment and spread of invasive floating macrophytes. The past thirty years of research and the implementation of nation-wide biological and integrated control programmes has led to widespread control of these species in many degraded freshwater ecosystems. Such initiatives are aimed at restoring access to potable freshwater and maintaining native biodiversity. However, in recent years, there has been a decline in populations of floating invasive plants, and an increase in the establishment and spread of submerged and emergent invasive plant species, which poses significant threats to aquatic ecosystems. This chapter highlights the vulnerability of South Africa's eutrophic systems to successful colonisation by this suite of new macrophytes following the successful biological control of floating invasive macrophytes, and explores a new regime shift in invasive populations partly driven by biological control. We suggest that a more holistic approach to the control of invasive plants would be required to ensure long-term ecosystem recovery and sustainability.