GONYAULACACEAE

Mead, A., Carlton, J. T., Griffiths, C. L. & Rius, M., 2011, Introduced and cryptogenic marine and estuarine species of South Africa, Journal of Natural History 45 (39 - 40), pp. 2463-2524 : 2470-2471

Family GONYAULACACEAE

Alexandrium tamarense -complex Introduced (Group I sensu Lily et al. 2007)

Saxitoxin-producing Alexandrium dinoflagellates are responsible for paralytic shellfish poisoning, which was unambiguously first reported from South Africa in 1948 ( Sapeika 1948). South African populations are genetically members of Group I of a monophyletic clade with origins in the northern hemisphere ( Lily et al. 2007). Reports of possibly historical paralytic shellfish poisoning incidents in South Africa, as early as 1888 ( Sebastian et al. 2005; Lily et al. 2007), do not preclude introduction by ballast water, which was already in international use by that time ( Carlton 1985). This complex includes several other species, including Alexandrium catenella . It seems probable that the modern-day (twentieth century) occurrences of Alexandrium tamarense in South Africa may be linked to increased shipping traffic during and after World War II.

Alexandrium minutum Halim, 1960 Introduced (Global clade sensu Lily et al. 2005)

Alexandrium minutum was first recorded in South Africa in 2003 when it formed a bloom in Cape Town Harbour ( Pitcher et al. 2007). Molecular analysis indicates that it groups with a monophyletic “global clade” found in Europe and in Western Australia, which Lily et al. (2005) suggested was native to Europe. Pitcher et al. (2007) suggest that “the same consideration can be made of the South African population present at Cape Town Harbour, moreover because this species has not been previously reported in the region.” Despite this comment, Pitcher et al. (2007) concluded their paper by noting that the phytoplankton flora of southern Africa is poorly known, and that “it is difficult to assess whether this first record of Alexandrium minutum in South African waters represents a new introduction to the region.” Nevertheless, we are compelled by the global genetic picture that paints a path back to the European-Mediterranean theatre as the biogeographic roots of this clade, which was probably dispersed through ballast water.