Physa mosambiquensis (Clessin, 1886) rediscovered?

An exotic fresh-water gastropod recently discovered in South Africa is identified as Aplexa (Stenophysa) marmorata (Physidae) and is considered conspecific with a population known from West Africa since at least 1911 and a single record from Mozambique dating from 1886. It is speculated that these introductions could have occurred via the Portuguese slave trade during the 16th and 17th centuries. A key to A. marmorata, another introduced physid Physa acuta and the indigenous, sinistral genus Bulinus is presente

Oysters as vectors of marine aliens, with notes on four introduced species associated with oyster farming in South Africa

Translocated oysters are well known to act as vectors of marine alien species, but to date this topic has received scant attention in South Africa, despite the fact that oysters have been imported into this region since 1894. Surveys of oyster farms in South Africa revealed four newly-recorded alien species: the black sea urchin, Tetrapygus niger, from Chile; the European flat oyster, Ostrea edulis (thought to be extinct since its intentional introduction in 1946); Montagu's crab, Xantho incisus, from the North Eastern Atlantic seas of Europe, and the brachiopod Discinisca tenuis from Namibia. Oyster imports are the most likely vector of all these species. The biological attributes of each species, the possible threats posed by their introduction, and the needs for additional control measures to limit or prevent further introduction and spread of alien species via oyster culture are discussed.Centre of Excellence for Invasion Biolog

The history and status of oyster exploitation and culture in South Africa

Both wild and cultivated oysters are consumed in South Africa. Edible wild oysters include Striostrea margaritacea, Saccostrea cucullata, Ostrea atherstonei, and O. algoensis, all of which occur along the south and east coasts, but not on the west coast. Wild oysters are exploited commercially, recrcationally, and by subsistence fishers, with S. margaritacea being by far the most intensively targeted species. Commercial harvesting of S. margaritacea takes place along the southern Cape coast and in KwaZulu-Natal (KZN), with the southern Cape hosting 102 of the 145 commercial pickers. Data on total annual commercial catch of oysters in the various harvesting areas are presented, but these are minimum estimates, because collectors do not always comply with harvesting regulations or fully report catches. Subsistence harvesting remains largely unmanagcd, except in KZN, and is particularly prevalent in the eastern Cape Province. The culture of oysters is dependent on imported Crassostrea gigas spat, mostly from Chile. Accurate annual oyster production statistics arc only available since 1985, although approximately 2 million C. gigas oysters are known to have been cultured annually throughout the 1970s and early '80s. Since then, production increased steadily from 1985 to 1991, peaking at some 8 million individuals, then declined to 2–4 million individuals from the mid 1990s onward. Although the market for oysters has grown, production has not kept up with demand, largely because of a lack of suitable locations for oyster culture. Finding suitable sites for cultivation along the northern Cape Province coast and establishing local oyster hatcheries for C. gigas are suggested as future priorities for the industry.Centre of Excellence for Invasion Biolog