Search

Marthasterias glacialisare found in the cool-temperate waters of the north-eastern Atlantic Ocean, in the subtropical waters of the Mediterranean Sea and along the south-western tip of Africa. The South AfricanMarthasteriaspopulation includes two morphotypes, a smooth, spinelessrarispinaform and a spinyafricanaform, that have been described as separate species, subspecies, orformaby various authors over the past century. To test whether these two morphotypes represent separate species, and whether either, or both, are conspecific with the North-East Atlantic species, 78Marthasteriaswere collected from the Cape Peninsula of South Africa. Morphological comparisons between individuals of the two forms showed no significant clustering of samples, indicating that there is no morphological separation of the two South African forms into distinct groupings. Theafricanaandrarispinaforms were also shown to be genetically indistinguishable, using a fragment of the mitochondrial cytochromecoxidase subunit I (COI) gene and the nuclear internal transcribed spacer 1 (ITS1). In addition, the COI sequences were also compared to those from European specimens, and phylogenetic reconstruction and intra- and interspecific levels of divergence suggested that the South African specimens form a single group that is genetically distinct from the EuropeanM. glacialis. Although the allopatric distribution, high genetic divergence (more than 3% for the COI fragment) and morphological differences suggest that the South African form should be raised to species status under the nameMarthasterias africana, further work must assess an independent genetic marker (nuclear) to support raising the COI clade to species level. TrueM. glacialishave a spine-armament pattern of a series of three or more regular spine rows down the length of each arm, whereasM. africanaare either covered in many irregularly spaced spines, or have an extraordinarily bare surface with only two spine rows per arm.Marthasterias africanamay also have an actinal spine simulating the presence of a third inferomarginal spine. This work tentatively resolves the taxonomic dispute, elucidates the separation and amalgamation of the two African forms and suggests a single, uniquely South AfricanMarthasteriasspecies that might be distinct from the north AtlanticM. glacialis, although further analyses to test reproductive isolation between the North-East Atlantic and South African forms are required. [ABSTRACT FROM AUTHOR]

South Africa lacks a commercial oyster hatchery. To inform the sourcing of seed for future hatchery establishments, we compared half-sib Pacific oysterCrassostrea gigascohorts from hatcheries in Namibia and Chile. We measured oyster growth, mortality, condition and feeding organ morphology in Algoa Bay (AB, Eastern Cape) and Saldanha Bay (SB, Western Cape), South Africa, from July 2011 to June 2012. Within SB, 14.3% of mean daily sea temperatures exceeded this species’ thermal optimum of 19 °C, compared to 50.5% in AB. Food abundance (mean daily chlorophyllaconcentration) in SB (7.8 mg m–3) was double that in AB (3.9 mg m–3) where, presumably to increase particle clearance rates in a relatively phytoplankton-poor environment, oysters had larger gill:palp surface area ratios. Plankton fatty acid profiles (indicators of food quality) differed between locations. In AB, instantaneous growth rates differed between cohorts, and trends varied seasonally. Within both locations, condition index was usually higher in Chilean oysters, whereas shell density was higher in Namibian oysters. In AB only, Chilean seed suffered substantially higher summer mortalities than Namibian seed, suggesting that the latter are more suited to temperatures in AB. AB should also be assessed for culture of the indigenous oyster species that occur there. [ABSTRACT FROM AUTHOR]

A catfish captured in the Breede River (33°56'41.6"S 20°4'45.6"E) in South Africa was identified using morphological and genetic techniques as the giant pangasius, Pangasius sanitwongsei Smith 1931, a new record for South Africa. The wild-caught specimen was a genetic match to juveniles purchased from the pet trade, and most likely originated from a release by an aquarist. Pangasius sanitwongsei is not on the list of fishes currently permitted for import into South Africa, and its presence in the pet trade illustrates the difficulty associated with preventing illegal introductions. [ABSTRACT FROM AUTHOR]