into the future of freshwater invasions in the country. As management of invasive
alien species is a legislated priority in South Africa, the likelihood of the importation
of alien freshwater biota, such as fishes, for intentional release is limited. Indeed
the number of naturalised fishes has been stable for several decades (Fig. 6.8).
It is also likely that the trend in discovery of new alien invertebrate taxa will
continue. This will be either the result of new invasions by contaminants or
stowaways in the international trade or, as was the case with the crayfish
P. clarkii, the result of discovery with increasing research effort. This is also
true for alien molluscs, most of which have been identified in KwaZulu-Natal
due to the greater search effort by the freshwater mollusc specialist Christopher
Appleton, who is based in this region.
Knowledge requirements for the management of invasive alien biota in freshwater environments include data on their taxonomic diversity, distribution and impact.
In South Africa, such knowledge is often limited to isolated case studies that lack the
geographic coverage required for effective decision-making. As a result, greater
investment in research securing contemporary data on all aspects of the invasion
process is an urgent requirement.
Acknowledgements We acknowledge use of infrastructure and equipment provided by the
SAIAB Research Platform and the funding channelled through the NRF-SAIAB Institutional
Support system. This study was partially funded by the National Research
Foundation—South African Research Chairs Initiative of the Department of Science and Technology (Inland Fisheries and Freshwater Ecology, Grant No. 110507). OLFW and TAZ acknowledge
support from the DSI-NRF Centre of Excellence for Invasion Biology. TAZ received support from
the National Research Foundation (Grant 103602) and thanks the South African Department of
Environment, Forestry, and Fisheries (DEFF) for funding the South African National Biodiversity
Institute noting that this publication does not necessarily represent the views or opinions of DEFF or
its employees. Thanks to Christopher Appleton and Gavin Snow for supplying literature. We thank
Linda Basson (University of the Free State) for providing photographs of parasitic protozoa and
Albert Chakona (NRF-SAIAB) for the photograph of the infestation of an Eastern cape Rocky.
References
Appleton CC, Miranda NAF (2015) Two Asian freshwater snails newly introduced into
South Africa and an analysis of alien species reported to date. Afr Invertebr 56:1–17. https://
doi.org/10.5733/afin.056.0102
Appleton CC, Forbes AT, Demetriades NT (2009) The occurrence, bionomics and potential impacts
of the invasive freshwater snail Tarebia granifera (Lamarck, 1822) (Gastropoda: Thiaridae) in
South Africa. Zool Med 83:525–536
Avidon S, Shelton JM, Marr SM et al (2018) Preliminary evaluation of non-native rainbow trout
(Oncorhynchus mykiss) impact on the Cederberg ghost frog (Heleophryne depressa) in
South Africa’s Cape Fold Ecoregion. Afr J Aquat Sci 43:313–318. https://doi.org/10.2989/
16085914.2018.1507898
Blackburn TM, Pyšek P, Bacher S et al (2011) A proposed unified framework for biological
invasions. Trends Ecol Evol 26:333–339. https://doi.org/10.1016/j.tree.2011.03.023
178
O. L. F. Weyl et al.
alien species is a legislated priority in South Africa, the likelihood of the importation
of alien freshwater biota, such as fishes, for intentional release is limited. Indeed
the number of naturalised fishes has been stable for several decades (Fig. 6.8).
It is also likely that the trend in discovery of new alien invertebrate taxa will
continue. This will be either the result of new invasions by contaminants or
stowaways in the international trade or, as was the case with the crayfish
P. clarkii, the result of discovery with increasing research effort. This is also
true for alien molluscs, most of which have been identified in KwaZulu-Natal
due to the greater search effort by the freshwater mollusc specialist Christopher
Appleton, who is based in this region.
Knowledge requirements for the management of invasive alien biota in freshwater environments include data on their taxonomic diversity, distribution and impact.
In South Africa, such knowledge is often limited to isolated case studies that lack the
geographic coverage required for effective decision-making. As a result, greater
investment in research securing contemporary data on all aspects of the invasion
process is an urgent requirement.
Acknowledgements We acknowledge use of infrastructure and equipment provided by the
SAIAB Research Platform and the funding channelled through the NRF-SAIAB Institutional
Support system. This study was partially funded by the National Research
Foundation—South African Research Chairs Initiative of the Department of Science and Technology (Inland Fisheries and Freshwater Ecology, Grant No. 110507). OLFW and TAZ acknowledge
support from the DSI-NRF Centre of Excellence for Invasion Biology. TAZ received support from
the National Research Foundation (Grant 103602) and thanks the South African Department of
Environment, Forestry, and Fisheries (DEFF) for funding the South African National Biodiversity
Institute noting that this publication does not necessarily represent the views or opinions of DEFF or
its employees. Thanks to Christopher Appleton and Gavin Snow for supplying literature. We thank
Linda Basson (University of the Free State) for providing photographs of parasitic protozoa and
Albert Chakona (NRF-SAIAB) for the photograph of the infestation of an Eastern cape Rocky.
References
Appleton CC, Miranda NAF (2015) Two Asian freshwater snails newly introduced into
South Africa and an analysis of alien species reported to date. Afr Invertebr 56:1–17. https://
doi.org/10.5733/afin.056.0102
Appleton CC, Forbes AT, Demetriades NT (2009) The occurrence, bionomics and potential impacts
of the invasive freshwater snail Tarebia granifera (Lamarck, 1822) (Gastropoda: Thiaridae) in
South Africa. Zool Med 83:525–536
Avidon S, Shelton JM, Marr SM et al (2018) Preliminary evaluation of non-native rainbow trout
(Oncorhynchus mykiss) impact on the Cederberg ghost frog (Heleophryne depressa) in
South Africa’s Cape Fold Ecoregion. Afr J Aquat Sci 43:313–318. https://doi.org/10.2989/
16085914.2018.1507898
Blackburn TM, Pyšek P, Bacher S et al (2011) A proposed unified framework for biological
invasions. Trends Ecol Evol 26:333–339. https://doi.org/10.1016/j.tree.2011.03.023
178
O. L. F. Weyl et al.