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Specimens of a mixed population of Sargassum spp. were collected from Reunion Rocks, KwaZulu-Natal, South Africa over a period of one year. Three general shapes of receptacle were recorded for Sargassum elegans, S. incisifolium and an undescribed species of Sargassum: i) terete, ii) three-cornered and iii) twisted receptacles respectively. The number of conceptacles on the receptacles was enumerated and related to the dry weight of the receptacles. It was found that conceptacle number per receptacle correlated well to the weight of the receptacle and that, each receptacle type had a different number of conceptacles per unit weight Relationships were found to vary from one season to the next, however, it was found that the three-cornered receptacle type developed a greater number of conceptacles per unit weight than the terete receptacle type. Reproductive:somatic biomass ratios indicated that the three-cornered receptacle type had a lower reproductive expenditure than the terete receptacle type in terms of biomass. Ecological and possible taxonomic implications are discussed.

Positron annihilation spectroscopy for chemical analysis (PASCA) has been applied to differentiate a multicomponent system from the individual constituents. The model catalysts used for this study were a Pt ion exchanged with mordenite and then extruded with Al2O3 and Pt impregnated onto a formed mordenite-Al2O3 extrudate. Differences were observed between the extrudates and mixed blends of the individual components. This result suggests that the extrusion may modify the location or interaction of the Pt and that PASCA has potential for the characterization of multicomponent catalysts.

Caulerpa taxifolia (Vahl) C. Agardh is an invasive marine alga in the northern Mediterranean Sea where it poses a serious threat to indigenous fauna and flora. Caulerpa taxifolia obtained through the aquarist trade in South Africa was grown under controlled temperature and irradiance conditions. Two separate univariate studies were performed: i) Temperature treatments of 15°, 20°, 25° and 30 °C, ail at 90 μmol photons.m - 2 .s - 1 irradiance and ii) irradiance treatments of 20, 75 and 130 μmol photons.m - 2 .s - 1 all at 25 °C. The optimum temperature for maximal stolon and assimilator extension was 25 °C; the alga showed growth as high as 30 °C with slight growth occurring as low as 15 °C. Growth of C . taxifolia was similar over the range of irradiance values studied. Maximum mean stolon and assimilator extension were recorded at an irradiance of 75 μmol photons.m - 2 .s - 1 . Caulerpa taxifolia commonly available in the South African aquarist trade was shown to have a wide temperature tolerance range, well within the range experienced by the east coast of the country.