The Rietvlei Dam near Pretoria, South Africa, provides drinking water for the city and for the wild life in the Rietvlei Nature Reserve, and is also used for recreational fishing. The dam is part of the Sesmyl Spruit system, which has a history of pollution, the major sources of which are industrial, agricultural and sewage from informal human settlements upstream of the reserve. With a large wetland separating the upstream Marais Dam and the Rietvlei Dam, the system has a high conservation priority status because of the high number of bird species that breed and roost in the various habitats. As part of a big aquatic health project in the Zoology Department, Rand Afrikaans University, aimed at finding suitable biomarkers for water quality monitoring in the system, this study was done to identify the major internal helminth parasites of the sharptooth catfish, Clarias gariepinus, that can be used in fish health assessment studies, and to determine their prevalence and intensity in the Rietvlei Dam. Fish were collected during one sampling survey and examined for endoparasites, also noting any ectoparasites that are recorded in routine fish health studies. Five species of helminths were identified: the adult cestodes, Polyonchobothrium clarias (intestine and stomach), Proteocephalus glanduliger (anterior intestine), the adult nematode Procamallanus laevionchus (stomach), larvae of the nematode Contracaecum sp. and many trematode metacercariae encysted in the muscles, of which only Ornithodiplostomum sp. was successfully excysted and identified. This trematode is recorded in South Africa for the first time, but could not be specifically identified because the reproductive system was still immature. Examination of piscivorous birds in the area or experimental infection of young birds are the only means by which the adult trematodes can be obtained. The adult cestodes and nematodes had specialised structures for attachment to the stomach and/or intestinal mucosa, adaptations associated with pathological effects in the host. Polyonchobothrium clarias had a crown of 26-30 hooks on its rostellum, and this number differs from those of specimens described from catfish in other African countries. Scanning electron microscopy showed that the rostellum of the P. clarias specimens from Rietvlei Dam was different from that of specimens from other localities in South Africa. Proteocephalus glanduliger in C. gariepinus from Rietvlei Dam differed in strobila size and size of glandular organ from specimens described by Janicki (Egypt) and Mashego (South Africa), the present specimens being much longer but with smaller glandular organs. Procamallanus laevionchus is a common parasite of catfish from many African countries, including South Africa, and scanning electron microscopy showed some form of transverse markings and presence of papillae-like structures at the posterior end of female specimens, an observation which was not described in previous studies. Larval Contracaecum are also common in C. gariepinus and other fish species, and adults have been identified in several species of fish-eating birds from South Africa. The sample size of fish collected in this survey was too low for a full health assessment index (HAI) study to be undertaken. Polyonchobothrium clarias and Contracaecum, however, were highly prevalent in the host species, and Contracaecum and Ornithodiplostomum occurred at high intensity (up to 44 and 140 respectively). Endoparasites of C. gariepinus can therefore be used in the fish HAI as a bioindicator of water quality. Only two ectoparasitic species were found on C. gariepinus: Argulus japonicus (skin and fins) and Lamproglena clariae (gills). Most water quality variables from the dam were within the target limits recommended by the Department of Water Affairs and Forestry, but the levels of inorganic nitrogen (nitrate and ammonia) and phosphorus (orthophosphate) exceeded the limit. If uncontrolled, these may lead to eutrophication of the dam. With the parasite species and diversity known, it is recommended that fish health assessments should be conducted along pollution gradients in the system to determine whether it can be incorporated into the suite of biomarkers for water quality monitoring of the Sesmyl Spruit system. / Prof. A. Avent-Oldewage

Water resources are frequently under inspection as pollution increases. Therefore an urgent need has arisen for sensitive bio-monitoring tools in toxicant impact assessment to indicate the effect of pollution on fish health in polluted aquatic ecosystems. Histopathological assessment of fish tissue allows for early warning signs of disease and detection of long term injury in cells, tissues or organs. Various biochemical and biological studies of fish have been used to assess the consequences of environmental toxicants on fish, but histology is able to enhance and add quality to the research carried out by identifying cellular alterations and quantifying the results. The aim of this study was to assess the degree of pollution in the Marais Dam (MD) and Rietvlei Dam (RVD) in the Rietvlei Nature Reserve (RNR) by determining the health status of the sharptooth catfish, Clarias gariepinus, using fish histology as a bio-monitoring tool.The MD and RVD situated within the Sesmyl Spruit serve to provide the area with water and are separated by a natural wetland. The dams were chosen for their elevated levels of toxicants. Four sampling surveys, two low flow and two high flow, were carried out over a period of two years. During each survey twenty fish were sampled per dam. Water and sediment were sampled for metal and endocrine disrupting chemical analysis. A standardized health assessment protocol employed to determine the effects of the toxicants included analysis of blood constituents, fish necropsy, calculation of condition factor and organosomatic indices, and a qualitative and quantitative histological assessment of three target organs: the gills, liver and gonads. These organs were removed and processed according to standard techniques for histological assessment. Histopathological alterations of each organ were identified (qualitative assessment) and subsequently quantified by means of a standard methodology of criteria to assess and compare fish health (quantitative assessment). The total index (Tot-I) values from the quantitative histological assessment were statistically analyzed using the ANOVA method. Potential endocrine disrupting chemicals and metals in the water of both dams were present at levels that could be toxic. The degree of pollution was more severe in MD than RVD. Examination of tissue from the gills, liver and gonads revealed marked histopathological alterations. The quantitative histological assessment indicated that fish collected from MD were in a significantly more severe histopathological condition than those of RVD. These results indicate that the wetland may still function as a natural filter. The qualitative and quantitative histological assessment objectively compared C. gariepinus specimens from MD and RVD and the effects of the toxicants on the health of the fish. / Dr. G.M. Pieterse

Eutrophication is a nutrient enrichment of dams and lakes. Increased eutrophication in dams results in blooms of cyanobacteria. Cyanobacteria are troublesome as they form massive surface scums, impart taste and odour to the water. Some strains of cyanobacteria such as Microcystis aeruginosa are dangerous to humans and animals. They produce toxins that can kill animals drinking the contaminated water and have also been implicated in human illnesses. The study investigated the effectiveness of techniques deployed in controlling cyanobacterial growth in Rietvlei, Roodeplaat and Hartbeespoort Dams. This was done by interpreting data from April 2010 to March 2012. The conditions in the three dams show that Microcystis produced toxins in the summer season and all the variables analysed were favourable for the production of toxins. The methods deployed to rehabilitate the dams do not completely solve the problems of toxins experienced by the dams. / Environmental Sciences / M. Sc. (Environmental Management)

Eutrophication is a nutrient enrichment of dams and lakes. Increased eutrophication in dams results in blooms of cyanobacteria. Cyanobacteria are troublesome as they form massive surface scums, impart taste and odour to the water. Some strains of cyanobacteria such as Microcystis aeruginosa are dangerous to humans and animals. They produce toxins that can kill animals drinking the contaminated water and have also been implicated in human illnesses. The study investigated the effectiveness of techniques deployed in controlling cyanobacterial growth in Rietvlei, Roodeplaat and Hartbeespoort Dams. This was done by interpreting data from April 2010 to March 2012. The conditions in the three dams show that Microcystis produced toxins in the summer season and all the variables analysed were favourable for the production of toxins. The methods deployed to rehabilitate the dams do not completely solve the problems of toxins experienced by the dams. / Environmental Sciences / M. Sc. (Environmental Management)

The Ceratium species occurring in the Vaal River since 2000, was identified as Ceratium hirundinella (O.F. Müller) Dujardin as proposed by Van Ginkel et al (2001). Ceratium hirundinella is known to cause problems in drinking water purification and has been penetrating into the final drinking water of Rand Water since 2006. Ceratium hirundinella is associated with many other water purification problems such as disrupting of the coagulation and flocculation processes, blocking of sand filters and algal penetration into the drinking water. Ceratium hirundinella also produce fishy taste and odorous compounds and causes discolouration of the water. The aims of this study were to determine the main environmental factors which are associated with the bloom formation of C. hirundinella in the source water and to investigate the influence of C. hirundinella on the production of potable water. In order to optimise treatment processes and resolve problems associated with high C. hirundinella concentrations during the production of potable water, jar testing and chlorine exposure experiments were performed. Multivariate statistical analyses were performed to determine the main environmental variables behind C. hirundinella blooms. Ten years data (2000 - 2009) from the sampling point C–VRB5T in the Vaal River, (5 km upstream from the Barrage weir) were used for this investigation, because C. hirundinella occurred there frequently during the ten year period. In this study, it was found that C. hirundinella was favoured by high pH, Chemical Oxygen Demand (COD), orthophoshapte (PO4), and silica concentrations, as well as low turbidity and low dissolved inorganic nitrogen (DIN) concentrations. No correlation was found between C. hirundinella and temperature, suggesting that this alga does not occur during periods of extreme warm or extreme cold conditions, but most probably during autumn and spring. The results of the multivariate statistical analysis performed with historical data from Vaalkop dam, indicate that the dinoflagellate C. hirundinella seems to be favoured by low temperature and turbidity, and high DIN, Fe, Methyl–orange alkalinity, Cd, PO4, Conductivity, pH, hardness and SO4 concentrations. In order to optimise treatment processes such as coagulation, flocculation and sedimentation, jar testing experiments were performed to investigate different coagulant chemicals namely: cationic poly–electrolyte only, cationic poly–electrolyte in combination with slaked lime (CaO) and CaO in combination with activated silica. Water from four different sampling localities were chosen to perform the different jar testing experiments: 1) sampling point M–FOREBAY (in the Forebay, connecting the canal to the Zuikerbosch Purification plant) near Vereeniging due to its proximity to the Zuikerbosch treatment plant, 2) M–CANAL_VD (upstream from the inflow of the recovered water from Panfontein) to determine the influence of (if any) the recovered water from Panfontein on Forebay source water, 3) source water from Vaalkop Dam (M–RAW_VAALKOP) and 4) source water from Rietvlei Dam (water from both Vaalkop and Rietvlei Dams contained high concentrations of C. hirundinella at that time of sampling) to determine which coagulant chemical is the most effective in removing high concentrations of C. hirundinella cells during the production of drinking water. The jar testing experiments with Vaalkop Dam and Rietvlei Dam source water (rich with C. hirundinella) indicated that using cationic poly–electrolyte alone did not remove high concentrations of C. hirundinella efficiently. However, when CaO (in combination with cationic poly–electrolyte or activated silica) were dosed to Vaalkop Dam source water a significant decrease of C. hirundinella concentration was observed. This indicates that the C. hirundinella cells were “shocked or stressed” when exposed to the high pH of the CaO, rendering it immobile and thereby enhancing the coagulation and flocculation process. However, when 10 mg/L CaO in combination with poly–electrolyte was dosed to Rietvlei Dam source water the turbidity and chlorophyll–665 results indicated that this coagulant chemical procedure was ineffective in removing algal material from the source water. The jar testing experiments using the cationic poly–electrolyte alone or cationic poly–electrolyte in combination with CaO on M–FOREBAY and M–CANAL_VD source water, showed a decrease in turbidity, chlorophyll–665 concentration, and total algal biomass, with an increase of coagulant chemical. When CaO in combination with activated silica was dosed, the inherent turbidity of the lime increased the turbidity of the Vaalkop Dam, M–FOREBAY and M–CANAL_VD source water to such an extent that it affected coagulation negatively, resulting in high turbidity values in the supernatant. Regardless of the turbidity values, the chlorophyll–665 concentration and total algal biomass (C. hirundinella specifically in Vaalkop Dam source water) decreased significantly when CaO was dosed in combination with activated silica. Therefore it was concluded that a cationic poly–electrolyte alone is a good coagulant chemical for the removal of turbidity, but when high algal biomass occur in the source water it is essential to add CaO to “stress” or “shock” the algae for the effective removal thereof. However, when CaO in combination with activated silica was dosed to Rietvlei Dam source water a decrease in turbidity and chlorophyll–665 concentration was found with an increasing coagulant chemical concentration. These results confirm the fact that coagulant chemicals may perform differently during different periods of the year when water chemistry changes and that certain coagulant chemicals may never be suitable to use for certain source waters. For the effective removal of algae during water purification, it is recommended that cationic poly–electrolyte in combination with CaO are used as coagulant chemical at the Zuikerbosch Water Purification Plant. Turbidity is not a good indication of algal removal efficiency during jar testing experiments. If problems with high algal concentrations in the source water are experienced it is advisable to also determine the chlorophyll–665 concentrations of the supernatant water during the regular jar testing experiments, since it will give a better indication of algal removal. Chlorine exposure experiments were performed on water from Vaalkop Dam (M–RAW_VAALKOP) and Rietvlei Dam source water, to determine the possibility of implementing pre– or intermediate chlorination with the aim to render the cells immobile for more effective coagulation. The chlorine exposure experiments with Vaalkop Dam and Rietvlei Dam source water showed similar results. The chlorine concentration to be dosed as part of pre– or intermediate chlorination will differ for each type of source water as the chemical and biological composition of each water body are unique. When the effect of chlorine on the freshwater dinoflagellate C. hirundinella was investigated, it was found that the effective chlorine concentration where 50 % of Ceratium cells were rendered immobile (EC50) was approximately 1.16 mg/L for Vaalkop Dam source water. For the source water sampled from Rietvlei Dam, it was found that the EC50 was at approximately 0.87 mg/L. Results of analyses to determine the organic compounds in the water after chlorination revealed that an increase in chlorine concentration resulted in increase in total organic carbon concentration (TOC), as well as a slight increase in MIB and trihalomethanes (CHCl3). Pre– or intermediate chlorination seem to be an effective treatment option for the dinoflagellate C. hirundinella to be rendered immobile and thereby assisting in its coagulation process. The use of pre– or intermediate chlorination to effectively treat source waters containing high concentrations of C. hirundinella is a viable option to consider. However, the organic compounds in the water should be monitored and the EC50 value for each source water composition should be determined carefully as to restrict cell lysis and subsequent release of organic compounds into the water. / Thesis (M.Sc. (Environmental Science))--North-West University, Potchefstroom Campus, 2012.

The Ceratium species occurring in the Vaal River since 2000, was identified as Ceratium hirundinella (O.F. Müller) Dujardin as proposed by Van Ginkel et al (2001). Ceratium hirundinella is known to cause problems in drinking water purification and has been penetrating into the final drinking water of Rand Water since 2006. Ceratium hirundinella is associated with many other water purification problems such as disrupting of the coagulation and flocculation processes, blocking of sand filters and algal penetration into the drinking water. Ceratium hirundinella also produce fishy taste and odorous compounds and causes discolouration of the water. The aims of this study were to determine the main environmental factors which are associated with the bloom formation of C. hirundinella in the source water and to investigate the influence of C. hirundinella on the production of potable water. In order to optimise treatment processes and resolve problems associated with high C. hirundinella concentrations during the production of potable water, jar testing and chlorine exposure experiments were performed. Multivariate statistical analyses were performed to determine the main environmental variables behind C. hirundinella blooms. Ten years data (2000 - 2009) from the sampling point C–VRB5T in the Vaal River, (5 km upstream from the Barrage weir) were used for this investigation, because C. hirundinella occurred there frequently during the ten year period. In this study, it was found that C. hirundinella was favoured by high pH, Chemical Oxygen Demand (COD), orthophoshapte (PO4), and silica concentrations, as well as low turbidity and low dissolved inorganic nitrogen (DIN) concentrations. No correlation was found between C. hirundinella and temperature, suggesting that this alga does not occur during periods of extreme warm or extreme cold conditions, but most probably during autumn and spring. The results of the multivariate statistical analysis performed with historical data from Vaalkop dam, indicate that the dinoflagellate C. hirundinella seems to be favoured by low temperature and turbidity, and high DIN, Fe, Methyl–orange alkalinity, Cd, PO4, Conductivity, pH, hardness and SO4 concentrations. In order to optimise treatment processes such as coagulation, flocculation and sedimentation, jar testing experiments were performed to investigate different coagulant chemicals namely: cationic poly–electrolyte only, cationic poly–electrolyte in combination with slaked lime (CaO) and CaO in combination with activated silica. Water from four different sampling localities were chosen to perform the different jar testing experiments: 1) sampling point M–FOREBAY (in the Forebay, connecting the canal to the Zuikerbosch Purification plant) near Vereeniging due to its proximity to the Zuikerbosch treatment plant, 2) M–CANAL_VD (upstream from the inflow of the recovered water from Panfontein) to determine the influence of (if any) the recovered water from Panfontein on Forebay source water, 3) source water from Vaalkop Dam (M–RAW_VAALKOP) and 4) source water from Rietvlei Dam (water from both Vaalkop and Rietvlei Dams contained high concentrations of C. hirundinella at that time of sampling) to determine which coagulant chemical is the most effective in removing high concentrations of C. hirundinella cells during the production of drinking water. The jar testing experiments with Vaalkop Dam and Rietvlei Dam source water (rich with C. hirundinella) indicated that using cationic poly–electrolyte alone did not remove high concentrations of C. hirundinella efficiently. However, when CaO (in combination with cationic poly–electrolyte or activated silica) were dosed to Vaalkop Dam source water a significant decrease of C. hirundinella concentration was observed. This indicates that the C. hirundinella cells were “shocked or stressed” when exposed to the high pH of the CaO, rendering it immobile and thereby enhancing the coagulation and flocculation process. However, when 10 mg/L CaO in combination with poly–electrolyte was dosed to Rietvlei Dam source water the turbidity and chlorophyll–665 results indicated that this coagulant chemical procedure was ineffective in removing algal material from the source water. The jar testing experiments using the cationic poly–electrolyte alone or cationic poly–electrolyte in combination with CaO on M–FOREBAY and M–CANAL_VD source water, showed a decrease in turbidity, chlorophyll–665 concentration, and total algal biomass, with an increase of coagulant chemical. When CaO in combination with activated silica was dosed, the inherent turbidity of the lime increased the turbidity of the Vaalkop Dam, M–FOREBAY and M–CANAL_VD source water to such an extent that it affected coagulation negatively, resulting in high turbidity values in the supernatant. Regardless of the turbidity values, the chlorophyll–665 concentration and total algal biomass (C. hirundinella specifically in Vaalkop Dam source water) decreased significantly when CaO was dosed in combination with activated silica. Therefore it was concluded that a cationic poly–electrolyte alone is a good coagulant chemical for the removal of turbidity, but when high algal biomass occur in the source water it is essential to add CaO to “stress” or “shock” the algae for the effective removal thereof. However, when CaO in combination with activated silica was dosed to Rietvlei Dam source water a decrease in turbidity and chlorophyll–665 concentration was found with an increasing coagulant chemical concentration. These results confirm the fact that coagulant chemicals may perform differently during different periods of the year when water chemistry changes and that certain coagulant chemicals may never be suitable to use for certain source waters. For the effective removal of algae during water purification, it is recommended that cationic poly–electrolyte in combination with CaO are used as coagulant chemical at the Zuikerbosch Water Purification Plant. Turbidity is not a good indication of algal removal efficiency during jar testing experiments. If problems with high algal concentrations in the source water are experienced it is advisable to also determine the chlorophyll–665 concentrations of the supernatant water during the regular jar testing experiments, since it will give a better indication of algal removal. Chlorine exposure experiments were performed on water from Vaalkop Dam (M–RAW_VAALKOP) and Rietvlei Dam source water, to determine the possibility of implementing pre– or intermediate chlorination with the aim to render the cells immobile for more effective coagulation. The chlorine exposure experiments with Vaalkop Dam and Rietvlei Dam source water showed similar results. The chlorine concentration to be dosed as part of pre– or intermediate chlorination will differ for each type of source water as the chemical and biological composition of each water body are unique. When the effect of chlorine on the freshwater dinoflagellate C. hirundinella was investigated, it was found that the effective chlorine concentration where 50 % of Ceratium cells were rendered immobile (EC50) was approximately 1.16 mg/L for Vaalkop Dam source water. For the source water sampled from Rietvlei Dam, it was found that the EC50 was at approximately 0.87 mg/L. Results of analyses to determine the organic compounds in the water after chlorination revealed that an increase in chlorine concentration resulted in increase in total organic carbon concentration (TOC), as well as a slight increase in MIB and trihalomethanes (CHCl3). Pre– or intermediate chlorination seem to be an effective treatment option for the dinoflagellate C. hirundinella to be rendered immobile and thereby assisting in its coagulation process. The use of pre– or intermediate chlorination to effectively treat source waters containing high concentrations of C. hirundinella is a viable option to consider. However, the organic compounds in the water should be monitored and the EC50 value for each source water composition should be determined carefully as to restrict cell lysis and subsequent release of organic compounds into the water. / Thesis (M.Sc. (Environmental Science))--North-West University, Potchefstroom Campus, 2012.