Balanus glandula: from North-West America to the west coast of South Africa
AbstractWe report the occurrence of the North-East Pacific intertidal barnacle Balanus glandula in the south-western African shores of the Atlantic Ocean. In addition, an attempt is made to trace the origin of the South African population by comparing the distribution of haplotype groups of two molecular markers, cytochrome oxidase subunit I (COI) and elongation factor 1 (EF1-α). The frequency of COI haplotypes in the South African specimens was most similar to that in specimens from Bodega Marine Laboratory and of Fort Bragg in Central California. Pairwise genetic distances demonstrated that the samples from Pillar Point were also similar to the Cape Town population. The frequency of EF1-α haplotype groups from Cape Town was most similar to that of Cape Blanco, Cape Meares and Westport Jetty, and, with lower p-values, to the populations of Cape Mendocino and Heceta Head. Pairwise genetic distances demonstrated that samples from Vancouver Island, Bodega Marine Laboratory and Heceta Head were also similar to the Cape Town population. Results indicate that the population of B. glandula from South Africa is most similar to the population from the northern portion of the Oregonian faunal province. It is possible that this is the origin of the South African population. As a result of this invasion, B. glandula out-competed the native African chthamalid species, Chthamalus dentatus. Thus, C. dentatus is presently very rare on the Atlantic South African shores.
Keywords: Balanus glandula, COI, competition, EF1-α, haplotypes, invasion, South Africa
African Journal of Marine Science 2008, 30(1): 85–92