22.3.1 Carcinus maenas (European Shore Crab)
Carcinus maenas has a broad distribution on four continents, but is native to the
north Atlantic and Baltic regions, and possibly to North Africa (see Robinson et al.
2020, Chap. 9; Hampton and Griffiths 2007). In South Africa, its distribution is
restricted to two harbours on the Cape Peninsula—Table Bay and Hout Bay (Mabin
et al. 2017). Between 2015 and 2016, a pilot management programme was
conducted in Hout Bay harbour, as part of a PhD project on C. maenas. The results
of the surveys suggested that although eradication may be feasible if sufficient
management effort was to be applied, C. maenas is not spreading outside harbours,
or into undisturbed habitats (Mabin et al. 2017). No further control is planned for this
species.
22.3.2 Tetrapygus niger (Chilean Black Urchin)
Although not the result of a control operation, the presence and subsequent disappearance of Tetrapygus niger in South Africa deserves mention. The urchin was
recorded at an onshore oyster farming facility in Alexander Bay on the north west
coast of South Africa in 2007 (Haupt et al. 2010). Since the initial observation,
oyster farming has ceased at Alexander Bay and the facility has been abandoned. In
2014 a re-survey of the two oyster farm dams in which the urchins has been recorded
as well as nearby intertidal and subtidal habitats was performed by researchers
(Mabin et al. 2015). No living T. niger were found in the dams or on the shore
and the population is thought to be extinct (Mabin et al. 2015). The 2014 survey was
funded by the Department of Environmental Affairs (DEA) through the
South African National Biodiversity Institute (SANBI) Marine Programme. Haupt
et al. (2010) judged the likely source of the urchins to be the importation of oyster
spat from Chile. Since the farming operations have ceased, re-introduction through
this pathway is unlikely.
22.4 Terrestrial Invertebrates
22.4.1 Otala punctata (Freckled Edible Snail)
Otala punctata is a helicid snail native to the Western Mediterranean and invasive in
the United States, Argentina, Uruguay and Chile. Herbert and Sirgel (2001) recorded
the eradication of O. punctata introduced to the Western Cape. The first population was
found at Tygerberg Hospital near Cape Town in December 1986 and the second
population at the Cape Town docks in January 1987 (see also Janion-Scheepers and
Griffiths 2020, Chap. 7). An eradication programme was started promptly under the
636
S. J. Davies et al.
Carcinus maenas has a broad distribution on four continents, but is native to the
north Atlantic and Baltic regions, and possibly to North Africa (see Robinson et al.
2020, Chap. 9; Hampton and Griffiths 2007). In South Africa, its distribution is
restricted to two harbours on the Cape Peninsula—Table Bay and Hout Bay (Mabin
et al. 2017). Between 2015 and 2016, a pilot management programme was
conducted in Hout Bay harbour, as part of a PhD project on C. maenas. The results
of the surveys suggested that although eradication may be feasible if sufficient
management effort was to be applied, C. maenas is not spreading outside harbours,
or into undisturbed habitats (Mabin et al. 2017). No further control is planned for this
species.
22.3.2 Tetrapygus niger (Chilean Black Urchin)
Although not the result of a control operation, the presence and subsequent disappearance of Tetrapygus niger in South Africa deserves mention. The urchin was
recorded at an onshore oyster farming facility in Alexander Bay on the north west
coast of South Africa in 2007 (Haupt et al. 2010). Since the initial observation,
oyster farming has ceased at Alexander Bay and the facility has been abandoned. In
2014 a re-survey of the two oyster farm dams in which the urchins has been recorded
as well as nearby intertidal and subtidal habitats was performed by researchers
(Mabin et al. 2015). No living T. niger were found in the dams or on the shore
and the population is thought to be extinct (Mabin et al. 2015). The 2014 survey was
funded by the Department of Environmental Affairs (DEA) through the
South African National Biodiversity Institute (SANBI) Marine Programme. Haupt
et al. (2010) judged the likely source of the urchins to be the importation of oyster
spat from Chile. Since the farming operations have ceased, re-introduction through
this pathway is unlikely.
22.4 Terrestrial Invertebrates
22.4.1 Otala punctata (Freckled Edible Snail)
Otala punctata is a helicid snail native to the Western Mediterranean and invasive in
the United States, Argentina, Uruguay and Chile. Herbert and Sirgel (2001) recorded
the eradication of O. punctata introduced to the Western Cape. The first population was
found at Tygerberg Hospital near Cape Town in December 1986 and the second
population at the Cape Town docks in January 1987 (see also Janion-Scheepers and
Griffiths 2020, Chap. 7). An eradication programme was started promptly under the
636
S. J. Davies et al.