The Mooi River catchment, in particular the Wonderfonteinspruit (WFS), has been the subject of a large number of studies regarding significant pollution sources, generally attributed to mining in the area. However, very little is known about the hydrochemistry of the surface water of the Klerkskraal, Boskop and Potchefstroom Dams in the Mooi River catchment. The aim of this study was to identify any hydro-chemical changes that occurred in the water quality of Klerkskraal, Boskop and Potchefstroom Dams during the period 1995 to 2010. Self-organised mapping (SOM) of the data emphasized the influence of mining-related effluents on the quality of the freshwater resources of the Boskop Dam and Potchefstroom Damrelative to Klerkskraal Dam which is located upstream of mining-related influences and which could therefore serve as a reference site. High concentrations of SO4 together with high electrical conductivity (EC) and total dissolved solids (TDS) values were evident in these dams as compared to Klerkskraal Dam. Concentrations of nutrients such as PO4, NH4 and NO3+ NO2 were however low in all three reservoirs. In Klerkskraal Dam, which is situated above the confluence of the WFS, a strong direct relationship between EC and total alkalinity (TAL) was exhibited. This suggests that Klerkskraal Dam is still a water source displaying natural unpolluted conditions, where increases in EC, TDS and TAL can be explained by natural dissolution of the bedrock. Boskop Dam presents a dam impacted by pollutants with no direct correlation between EC and TAL. During the current study both SO4 concentrations as well as Na+ concentrations exhibited a decline from 1995 until 2010 in Boskop Dam. This suggests that, although Boskop Dam still carries the burden of mining pollution via the WFS, the pollution levels of the freshwater of Boskop Dam have decreased between 1995 and 2010.

An ecologically healthy Mooi River system is important for maintaining the quality of potable water of Potchefstroom and surrounding areas. However, this system is under constant threat from anthropogenic pollution arising from both agricultural and mining activities in its catchment. A survey of planktonic algal and cyanoprokaryote assemblages in Klerkskraal, Boskop and Potchefstroom reservoirs was undertaken during 1999–2000 and 2010–2011. In all three dams, total algal and cyanoprokaryote concentrations were lower during the second survey (2010–2011), suggesting an improvement in ecosystem health. However, results also show a change from a Chrysophyceae-dominated community to one dominated by Bacillariophyceae. Increased numbers of diatom species that usually occur in eutrophic impoundments ( Melosira varians, Cyclotella meneghiniana and Aulacoseira granulata ) indicate an increase in the trophic status of the reservoirs, especially that of Boskop Dam, a trend mirrored by increases in conductivity as well as phosphorus and ammonium concentrations in all three reservoirs. It can therefore be concluded that although the ecosystem health of the Mooi River system is currently still good, further increases in nutrients such as phosphorus can cause proliferation of problem species (detected in enrichment cultures) and a deterioration of its water quality. Keywords : Mooi River reservoirs, algal communities, cyanoprokaryotes, water quality

The aim of this study was to determine the efficacy of ozone in water purification processes at the Midvaal Water Company, which uses the hypertrophic Middle Vaal River for source water. It was found that pre- and intermediate ozonation had no significant effect on pH, conductivity, dissolved organic carbon (DOC) and total organic carbon (TOC). Chlorophyll-a, total chlorophyll, spectral absorbance coefficient (SAC 254) and total algal cells were not influenced by pre- ozonation (as desired) but were greatly reduced after intermediate ozonation. The dissolved air flotation step which occurs after pre-ozonation and prior to intermediate ozonation contributed to an average total chlorophyll removal of 74%. The effect of ozonation on the removal of manganese, iron and aluminium could not be determined during this study since these elements were present in relatively low concentrations in the source water. Intermediate ozonation had variable effects on the removal of Cyanophyceae, Dinophyceae, Euglenophyceae and Chlorophyceae, but Chrysophyceae, Bacillariophyceae and Cryptophyceae were greatly reduced after this stage.

The aim of this study wasto look at the changes in the water quality of Boskop dam over a period from 2000 to 2010 inorder to use it as a baseline for any change in water quality that may occur if proposed mining activities take place.

The aim was to investigate the presence of cyanobacteria as well as algae on minetailings storage facilities that have undergone rehabilitation for different periodes of time aswell as to correlate the presence of these species with the physical and chemical characteristicsof the mine tailings.

The presence and abundance of cyanobacteria and algae in the air on mine tailings storage facilities that is rehabilitated for different periods were determined.

We studied the diversity of algae (desmids and diatoms) and cyanoprokaryota in freshwater and aerophytic biotopes in the Drakensberg (South Africa and Kingdom of Lesotho).Diversity, species composition and distribution of the taxa, their ecological characteristics, level of endemism and perspectives of taxonomical studies are being discussed.Special attention was paid to the study of desmids which are poorly investigated in the Drakensberg.Our work on the mountain tarns around the Giant's Cup area (UKhahlamba-Drakensberg National Park) revealed a total of 86 species from 18 genera of saccoderm and placoderm desmids (87 intraspecific taxa).Desmids belonging to the families Mesotaeniaceae (3 species), Gonatozygaceae (2), Closteriaceae (9) and Desmidiaceae (72 species, 73 intraspecific taxa) were identified.Most diverse families are: Gonatozygaceae (2), Closteriaceae (9) and Desmidiaceae (72 species, 73 intraspecific taxa).As the result of our studies 1 genus (Teilingia Bourr.) and 28 species (3 species and 2 varieties from them will be described as new for science) were recorded in Southern Africa for the first time.Our data revealed a high algal diversity in the Drakensberg and confirmed that the Drakensberg (together with the Cape region, Waterberg, Caprivi Strip, Swaziland, Karoo and Namib deserts) is one of the most diverse algal areas in Southern Africa.

In 1991 Oscillatoria simplicissima replaced Microcystis aeruginosa in the Vaal River, South Africa. This study explored the reason for this succession by looking at the photosynthetic performance of these two cyanoprokaryotes at different temperatures, light intensities and N:P ratios. Microcystis aeruginosa showed higher growth rates and chlorophyll a concentrations than O. simplicissima for most treatments, except the N-deficient treatments. It seems that M. aeruginosa can maintain growth under a range of different conditions and can keep forming mass occurrences, but has high light requirements for photosynthesis and maintenance and can tolerate a much higher light intensity without experiencing photo-inhibition. Oscillatoria simplicissima, on the other hand, is able to harvest available light more efficiently at 25 degrees C and 15 mu mol m(-2) s(-1), experiences less damage or loss at antenna level and retains more of its electron transport capabilities than Microcystis, giving it a competitive edge over M. aeruginosa under these environmental conditions.

Oscillatoria simplicissina is a filamentous blue green alga that was identified in the Vaal River in South Africa. The magnitude of its blooms causes a decline in water quality as well as problems in extracting and purifying water. The species was classified as Oscillatoria simplicissima under the order Nostocales and the family Oscillatoriaceae due to its simple unbranched trichome without heterocysts and akinetes. However, it was reclassified under the species Microcoleus lyngbyaceaus because of the thick outer walls of its terminal cells. The classification was again changed to Phormidium simplicissimum. Therefore, apart from looking at the ultrastructure of this organism this investigation also tried to unravel the classification of this species.