OSTREIDAE, Rafinesque, 1815

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 : 2496-2497

Family OSTREIDAE

Ostrea edulis Linnaeus, 1758 Introduced

This well-known European flat oyster is identified by a cup-shaped lower valve and flat upper one. It has been widely distributed around the world by the aquaculture industry. For example, populations are now common in areas along the Nova Scotia, Maine and Massachusetts coasts, following its introduction to the Gulf of Maine in the 1940s ( Robinson, Griffiths, McQuaid et al. 2005). It was intentionally introduced to Knysna in 1946 without success ( Korringa 1956). Surveys by us in 2008 found a reproducing population in the Alexander Bay oyster dams on the west coast of South Africa ( Haupt et al. 2010a).

Crassostrea gigas (Thunberg, 1795) Introduced

A deep lower valve, flat upper valve and undulating margins are the identifying features of this oyster, which is widely cultured around the world in both marine and estuarine habitats. Originally from Japan, populations are now widespread, notably in Europe, Australia and New Zealand. It was introduced to South Africa for culture purposes in 1955, but it was not until 2001 that wild populations were first detected ( Robinson, Griffiths, Tonin et al. 2005). Naturalized populations are currently known from the Breede, Goukou and Knysna Estuaries, all along the southern coast ( Haupt et al. 2010b).