discovery rate of 6.5 species per decade. Notably, since 2000, 27 further new species
have been recognised, a discovery rate of 15 species per decade. While increased
attention to marine invasions has undoubtedly contributed to the accelerating trend
in recognised introductions, the fact that new introductions continue to be noted in
historically well-studied and frequently-surveyed regions such as Saldanha Bay
(Peters and Robinson 2018) suggests an increase in the rate of new introductions.
A large proportion of species (44%) introduced to the coast of South Africa
originate from the North Atlantic Ocean (Fig. 9.2) with most being native to the
coasts of Europe, the United Kingdom and northern Africa. Interestingly, only 15%
of introduced species have their origins in the southern hemisphere. This pattern is
Fig. 9.1 The taxonomic breakdown of alien taxa known from along the South African coast
Table 9.1 (continued)
Taxonomic
group
Species
Ecoregion
Southern Benguela Agulhas Natal Delagoa
CHORDATA
Ascidiacea
Diplosoma listerianum
√
√
√
Microcosmus squamiger
√
√
RHODOPHYTA
Antithamnionella
spirographidis
√
√
Asparagopsis armata
√
√
√
Asparagopsis taxiformis
√
√
CHLOROPHYTA
Cladophora prolifera
√
Codium fragile
√
√
9 Coastal Invasions: The South African Context
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