Marine bioinvasions in South Africa – status and states of knowledge

Marine bioinvasions in South Africa – status and states of knowledge
Charles L. GRIFFITHS1, Tamara B. Robinson2
1Centre for Invasion Biology, Department of Biological Sciences, University of Cape Town, Rondebosch 7701
2Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Matieland, 7602

This presentation aims to gives an updated overview of the current status and state of knowledge of marine bio-invasions in South Africa. The last major published reviews of this topic were those of Mead et al. in 2011. Since then, four species have been removed from the introduced list, one being reassigned as cryptogenic, two having become locally extinct and one being transferred to the terrestrial list. Six species have also been formally added to the list, while others (several barnacles, a porcelain crab, a littoral earwig and a starfish) have been reported, but are yet to be formally included in the list. We introduce these new species and summarize the taxonomic composition of the introduced biota, review their probable vectors of introduction, their areas of origin, their current distributions patterns and their rates of introduction. By applying standardized terminology to categorise the 89 formally accepted species as either ‘alien’ (i.e. species whose presence is attributable to human mediated transport) or ‘invasive’ (i.e. species having self-replacing populations over several generations and which have spread from their point of introduction) we currently recognise 36 alien species and 53 invasive species. We also reflect on the research done on this topic in South Africa to date. Numbers of publications are increasing, but are focussed on few species and largely on distributional studies, with little emphasis of mode of introduction or impacts, and little experimental work.  We conclude by identifying 10 species we consider most in need of further investigation.