M.Sc. (Environmental Management) / Wetlands play a significant role in our environment as they provide a variety of goods, services and benefits to living species ranging from humans, animals and plants to microorganisms. Despite their importance, wetlands have somewhat been neglected over the past few years which has led to a rapid deterioration of wetland conditions and functions. Wetlands provide unique functions that cannot be provided by any other ecosystem; their value was recognised in the 1960s. Prior to this realisation the value of wetlands had been seriously underestimated to the extent where they were even previously labelled as “wastelands”. The reality is that to date minimal measures have been put in place to assist in the rehabilitation and future conservation of wetlands. The lack of wetland management and monitoring can be attributed to the fact that very little is known about the functioning of some of the wetland systems. Endorheic wetlands have recently been emerging as ecosystems of importance. Very little is known about endorheic wetlands and their ecological functioning. To date a fair amount of studies have been conducted on the pans in Mpumalanga and in the Free State but minimal information exists on the pans in the North West Province. The objectives of this study were therefore to compare the abiotic and biotic composition of pans in Mpumalanga and North West Provinces, in order to contribute to the knowledge which will eventually assist in devising rehabilitation measures and future conservation of pans in the area. Three different water ecosystem components were studied; these included aquatic invertebrate communities, water quality and sediment characteristics. The collected water samples were taken to an accredited laboratory to be analysed. When compared between the two provinces, the water-quality results indicated differences between provinces as well as among individual pans. However, most of the pans in both provinces show characteristics of being dystrophic alkaline systems. The invertebrates were collected using sweep nets and stored in jars containing 5% neutrally buffered formalin and a staining agent (Rose Bengal). The sediment characteristics were determined by using standard techniques and results showed that there were no obvious similarities between the different pans in the different provinces. Water-quality analyses were performed on samples taken during both winter- and summer-sampling surveys and these samples were analysed by a reputable laboratory. Based on the analyses of the invertebrate community samples, 25 taxa were identified; results show similarities in the structure of communities in both provinces with the exception of one or two different species. Sampling was conducted over a period of two seasons at all sampling points and several species were found belonging to different families. Invertebrates sampled in Mpumalanga pans were similar to those reported in previous studies done in the area and most of the invertebrates sampled in Mpumalanga and the North West are known to be commonly found in temporary habitats. Spatial and temporal variations in invertebrate assemblages were determined; this analysis displayed differences in the different variables (biotic, physical and chemical) tested over the two seasons. The pans in Mpumalanga were dominated by coarse sand. Large amounts of coarse sand accompanied by poor water quality were observed in MP Pan A in Mpumalanga Province; this could be an indication of somewhat poor catchment management. The results of the abiotic and biotic comparison show that there are minor similarities and differences among the selected pans studied in each province. The knowledge acquired can now be utilised to enhance the available literature on these pans. Long-term studies have to be done to better understand the ecological functioning of the pans in the North West Province in order to devise mitigation measures as well as appropriate rehabilitation strategies and conservation measures.

M.Sc. (Aquatic Health) / The Bojanala Platinum District (BPD) in North West Province (NWP) is a well-established mining and agricultural region of South Africa. These activities result in surface runoffs that are likely to pollute nearby freshwater impoundments, including the Roodekopjes (RD) and Vaalkop Dams (VD). These impoundments support subsistence fishing, where the fish caught, are often the sole source of dietary protein for local communities. The aim of this study was two-fold: firstly, to assess the health status of the fish in these impoundments by (i) conducting a necropsy-based macroscopic evaluation, (ii) calculating appropriate biometric indices, and by (iii) performing a semi-quantitative histology-based fish health assessment (HBFHA) on selected target organs of two freshwater fish species, namely Clarias gariepinus (Sharptooth Catfish) and Cyprinus carpio (Common Carp). Secondly, the edibility (safe for human consumption) of these fish species was to be determined by (i) quantifying the bioaccumulation of selected organic and inorganic toxicants within the muscle of the fish collected and (ii) assessing the resultant potential health risk/s through consumption toward consumers of these fish. In addition, in situ physico-chemical parameters were measured and samples of water and sediment were collected for laboratory analysis at each of the assessed impoundments. Otoliths and scales were also collected for age estimation. Tissue samples for histology were fixed in formalin (liver, kidney & heart) and Bouin’s (gills, gonads & skin) solution and processed for light microscopy analysis using standard histological techniques. Water, sediment and muscle samples were analysed for organic and inorganic toxicants by accredited laboratories using ICP-MS & ICP-OES. Results from the two assessment sites (RD & VD) were assessed against a reference site, the Marico-Bosveld Dam (MBD).

Ph.D. (Zoology) / Please refer to full text to view abstract

M.Sc. / The water quality monitoring project undertaken on the Blyde River in Pilgrim's Rest and surrounding area, provided information on various parameters. These included the macro variables (pH, temperature, conductivity, dissolved oxygen concentration, oxygen saturation percentage and turbidity), micro variables (ionic and metal concentrations) and fauna (fish and invertebrates). Field and experimental data were integrated to form a realistic and representative picture of the general state of health of the Blyde River. The macro variables (pH, temperature, conductivity, dissolved oxygen concentration, oxygen saturation percentage and turbidity) were all within the guideline limits as provided by the Department of Water Affairs and Forestry. The ionic concentrations (calcium, magnesium, sodium, chloride and nitrate) were acceptable and conformed to guideline values. The aquatic macro-invertebrate and habitat quality survey indicated that most of the sampling sites could be described as good. Sampling site 2 (next to reduction works) was classified as poor. This is the result of mining activity at this specific site situated at the rock dump at Peach Tree Creek. The extensive disturbance of the habitat is the result of 130 years of mining activities. The metal concentrations in the Blyde River exceeded the guideline limits, except for manganese. Aluminium toxicity is pH dependent, and increases with a decrease in the pH. The alkaline pH in the Blyde River acts as a buffer against the aluminium toxicity. The lead concentration in the Blyde River exceeded the Department of Water Affairs and Forestry guideline limit. Lead is hazardous to most forms of life. Zinc is toxic to fish and aquatic organisms at relatively low concentrations. Although nickel is a natural element of the earth and water, mining activities cause nickel emissions and an increase in the nickel concentrations in water systems. Copper is regarded as a highly toxic metal if present in high concentrations. Iron is not easily absorbed by aquatic organisms and because of its limited toxicity and bioavailability, described as a noncritical element. Chromium is biologically inert. Despite of a lack of information on the concentrations of metals in the Blyde River before the onset of mining activities at Pilgrim's Rest, it is clear that the extensive disturbance of the habitat at Peach Tree Creek and Vaalhoek, and to a lesser extent at Delvers' Creek exists. Present and past mining activities in the Pilgrim's Rest area resulted in the deterioration of the water quality in the Blyde River. Rehabilitation of the area around the rock dump at Peach Tree Creek will have to be done to prevent seepage from the rock dump and disturbed area to the river. Measures, such as the construction of paddocks and berm walls to collect seepage before it reaches the river, will have to be implemented. The water will then have to be treated before releasing it into the river. The acute, sub-lethal toxicity tests with nickel and lead were conducted based on the concentrations as derived from water samples taken from the Blyde River, during the monitoring phase of the project. The results of the blood physiological experimentation indicated that normal physiological functioning were disturbed when fish were exposed to sub-lethal concentrations of lead and nickel. Results indicated that stimulation of the immune system, osmotic stress and hypoxic conditions arise after lead and nickel exposure. Hypoxia arises because of a deficiency in the amount of oxygen reaching bodily tissues. Osmotic stress is a result of affected gill and kidney functioning. The metabolic variables indicated that the metabolism of trout was affected, because of stress associated with metal exposure. The nervous system functioning was also, affected, as derived from the enzymatic variables. Taking these factors into consideration, the normal functioning and survival of rainbow trout (Oncorhynchus mykiss) is hindered. The acute, lethal toxicity tests of nickel on rainbow trout (Oncorhynchus mykiss) and chubby head barb (Barbus anoplus) were performed using nickel concentrations as determined in the Blyde River. The 100% mortalities recorded, when exposing the fish to these concentrations, indicated that the Blyde River provides a buffer action against the toxic effect of nickel on the aquatic organisms. Should this buffer action be disturbed, for instance a sudden drop in water pH, the toxicity of nickel will increase and have detrimental effects on the aquatic organisms. Further deterioration of the water quality in the Blyde River should be avoided at all cost. Large scale yellow fish (Barbus marequensis) were only found at sites below sampling site no 8, which is alarming and a further confirmation of habitat degradation. To prevent further degradation of the water quality in the Blyde River annual biomonitoring in conjunction with experimental studies are suggested to obtain information, which enables effective managerial decision making. Measurements should be taken to reduce the impacts of mining and agricultural activities, if future studies indicate further water quality degradation. Objectives regarding the health of the aquatic environment should be set and actions taken to prevent the impactors from doing further harm. The Pilgrim's Rest area can be developed for Eco-tourism, and therefore the aim should be to create awareness of the river and its surroundings and involve people in the conservation thereof.

M.Sc. (Zoology) / Sediment contamination occurs as a result of various anthropogenic activities; mainly through mining-, agricultural- and industrial practices. Many of the contaminants arising from these activities enter the aquatic system and precipitate from the surrounding water, binding to sediment particles. In the sediment compartment, these contaminants reach concentrations much higher than in solution with the overlying water. Even though the quality of the overlying water may prove acceptable in accordance to water quality uidelines, an aquatic system may still be at risk from the contaminated sediment. If the contaminated sediment were to be disturbed through flooding, bioturbation or changes in the water chemistry, these contaminants will desorb into the water column and as a result be detrimental to life forms in contact and dependent on that water source. Monitoring sediment has been a widespread initiative internationally and has led to the development of various sediment toxicity test methods, including different bioassays. This study focused on sediment bioassays such as the Phytotoxkit-F and Ostracodtoxkit-F, and the Diptera bioassay to assess the sediment quality of the Tweelopiespruit-Rietspruit-Bloubankspruit (TRB) river system in Gauteng, South Africa. This river is known to be impacted by acid mine drainage (AMD) since late August 2002. Exposure of the bioassays to river sediment from preselected sampling sites (Site 1, closest to the mine, to Site 6, furthest from the mine, and Site 7, the reference site) provided an eco-toxicological estimation of the acute toxicity emanating from contaminants in the sediment. Physico-chemical analyses revealed high concentrations of metals and other contaminants in the water and sediment. A general linear decrease in contaminant concentrations was observed from Site 1 to Site 6. The results from the bioassays displayed a similar trend, since there were greater sensitivities (mortalities and growth inhibition) to sediments sampled closer to the mine. Due to high levels of contamination in sediments, compared to the overlying water, and the potential impact on aquatic organisms, sediment toxicity monitoring should be a compulsory requirement for environmental studies in South Africa

An understanding of species specific water quality requirements is essential for efficient production of aquaculture products, an aspect not well documented for the land-based culture of the South African abalone, Haliotis midae. In order for the industry to remain competitive in international markets, efficient use of water supplies and the development of water reuse technology is needed. This study assessed the changes in water quality between tanks in a tiered serial-use raceway in relation to accumulated biomass and water flow and estimated the flow index (FI) (L h⁻¹ kg⁻¹) at which growth becomes significantly affected. The effect of dietary protein level, supplementation of pure oxygen and addition of sodium hydroxide (NaOH⁻) on water quality and fundamental production parameters in the serial-use raceways was also assessed. The serial-use raceways were used as a tool to create a range of water quality conditions at which the growth, feed conversion ratio (FCR) and condition factor (CF) of "cocktail" size (60 – 70 mm) H. midae could be monitored. The metabolic activity of the abalone resulted in a deterioration in water quality between tanks in series. pH (r² = 0.99; p < 0.001) and dissolved oxygen concentration (r² = 0.99; p < 0.001) were positively correlated with flow index (pH = 7.38 FI°·°² ; dissolved oxygen = 6.92 FI°·°⁴), while free ammonia nitrogen (FAN) (r² = 0.99, p < 0.001) and nitrite (NO²⁻ - N) (r² = 0.93, p < 0.001) were negatively correlated with flow index (FAN = 8.02 FI⁻°·⁷¹). Nitrite concentrations increased over time indicating colonisation of Nitrosomonas bacteria on the basket surfaces. A flow index of 7.2 – 9.0 L h⁻¹ kg⁻¹ was estimated as the minimum to avoid significant reductions in weight and shell length gain and increases in FCR values. Total ammonia nitrogen (TAN) and FAN concentrations were significantly correlated to dietary protein (P) (t = 6.63, p < 0.0001 and t = 6.41, p < 0.0001, respectively) and flow index (t = 5.42, p < 0.0001 and t = 3.9, p < 0.0002, respectively) and could be estimated using the models TAN = 9.73 P – 110.3 log (FI), and FAN = 0.132 P – 1.10 log (FI). Mean FAN concentrations were 67 and 41 % lower in tanks fed a diet containing 22 and 26 % protein respectively, when compared to tanks fed a 33 % protein diet. Supplementation with pure oxygen (103 ± 8 % saturation) improved shell length gain (t = 3.45, p = 0.026) in abalone exposed to high FAN (2.43 ± 1.1 μg L⁻¹) and low pH (7.6 ± 0.13), relative to a treatment with no oxygen supplementation (92 ± 6 % saturation). Addition of a sodium hydroxide solution resulted in elevated mean pH in treatment raceways when compared to control raceways. The increased pH resulted in significantly higher weight gain (g abalone⁻¹) (F₁·₁₂ = 4.51; p = 0.055) and shell length gain (mm abalone⁻¹) (F₁·₁₂ = 4.56; p = 0.054) at an α-error level of < 5.5 %. In two trials, weight gain and shell length gain were significantly correlated to pH (p < 0.001), and multiple regression of pH, dissolved oxygen and FAN consistently revealed pH to be the best predictor of growth. It is therefore suggested that decreasing pH is the first limiting water quality variable for abalone in serial-use raceways. As a decrease in water pH is linked to respiration by the abalone and subsequent increase in dissolved carbon dioxide (CO₂) concentration, future studies should examine the effects of CO₂ on H. midae metabolic rate, calcification rate and health. The results of this study will contribute toward our understanding of the specific water quality requirements for H. midae in commercial aquaculture systems, and influence the design and management procedures for abalone water reuse systems.

M.Sc. Aquatic Health) / The Klip River runs past heavy urbanization and industrialization as a consequence it is possibly one of the most abused river systems in Gauteng and perhaps the country as a whole. Eight sites were selected along the course of the Klip River for biomonitoring purposes. The sites were selected to represent the upper, middle and lower reaches of the river, while sites representing point source pollution sources were also included. Various biomonitoring techniques have been included to determine the present ecological state of the Klip River. This includes biotic indices to assess the ecological integrity of the fish and invertebrate communities and the habitat. In addition, fish health was assessed using a variety of histological, biomarker and bioaccumulation based assessments. From the results it is evident that the sites on the Klip River represent the three main regions of a river including headwaters, middle reaches and a mature river. These natural changes in river ecology also caused natural variations in the habitat availability and the resultant biotic communities. There were, however, many changes not related to these natural variations but rather the numerous anthropogenic activities present on the river. The most noticeable change has occurred due to alteration in the flow regime. These changes are brought about by the many weirs and bridges in the system, return flow from the numerous settlements and agricultural activities and the various WWTW. These alterations in flow have caused serious erosion of the stream banks and may lead to siltation of the system. It is clear from the results of the sediment particle size analysis that there is an increase in the percentage contribution of medium and very fine sand below site 3. This is a good indication that the increased flow below the Olifantsvlei WWTW is already causing siltation. Ultimately this can lead to loss of riffle habitat within the river. These flow alterations have also caused an alteration to habitat availability and quality and as a result caused a modified invertebrate community. The macroinvertebrate community at all the sites (below site 1) consisted of taxa that are tolerant to pollution. This is also reflected in the poor SASS 5 and ASPT scores observed at the various sites. These tolerant organisms probably occur in the system due to an altered habitat template and a change in water quality. It is important to note that although the values obtained for the water quality variables are within the TWQR that the oxygen saturation at some sites decreased. These sites included the sites below the Olifantsvlei WWTW, after the confluence with the Rietspruit and the last monitoring site. The Fish Health Assessment Index scores were the highest at site 3 and decreased to site 8. This indicated that the fish condition improved from site 3 to site 8. However, there was a large variation in the index scores from the individual specimens. The results of this assessment cannot be compared to other studies as no fish health assessment index has been applied on the Klip River. This study will serve as a baseline assessment for future studies of the fish health of the Klip River. The results of the metal analysis in the fish muscle tissue indicated relatively low levels that correspond to levels measured by Kotze (1999) while still being lower than fish sampled from the polluted Olifants River. It is therefore recommended that further studies be completed on the fish health of the Klip River and that the fish health of specimens in the Klip River is compared to those of the Vaal River to determine the impact of the Klip River system on the Vaal River. As it has become clear that the Rietspruit also influences the water quality of the Klip River it is recommended that further studies be completed on the Rietspruit to determine the cause of the impacts. Because the histological alterations identified may be the result of a range of different biological and/or chemical stressors, it is difficult to assign specific causative agents for the various alterations identified. Based on the selected parameters investigated, the results show that fish in the Klip River appears to be in a relatively healthy condition and the organs seem to be in a functional state. Establishing a histology-based monitoring programme for fish health in the Klip River, by incorporating appropriate sample sizes and various fish species is recommended. Monitoring of biological responses for assessing the significance of pollutants has become a reasonable measurement in biomonitoring, and use of biomarker responses has played a significant role in this aspect. However, no biomarker has been validated as a unique tool to determine the effects of pollutants on organisms. Furthermore, it is necessary to understand how bioaccumulation and biomarkers relate to each other on exposure to specific pollutants and how it varies between species, to interpret the effects of pollutant exposure in both the field and laboratory. The results obtained in this study indicate that there are definite impacts on the entire system, although these have not altered fish biology and functionality to a large extent. However, sample size should be considered when evaluating individual biomarker responses, as a larger sample size will be more representative of the resident fish community’s response to the pollutants and other stressors. It is difficult to assign specific stressors for the various biomarker responses identified. It is recommended that further biomarker studies be undertaken on the Klip River to increase the level of confidence in the results obtained.

M.Sc. / The purpose of this study was to determine whether unpaved roads in commercial forests have a detrimental impact on aquatic macro-invertebrates in the receiving rivers associated with these roads. The upper section of the headwaters of the Motlhaka-Semeetse River was chosen as the Study Area because a portion is situated in the Wolkberg Wilderness area (natural area with no roads) and a portion in a commercial forestry plantation (high road network density). Stream conditions based on a rapid bio-assessment of aquatic macro-invertebrates using SASS5 were then compared between the two catchments amid 2002 and 2010. In order to support the SASS5 results, daily rainfall data from December 1959 to October 2010 was collated and compared to daily stream flow data from January 1960 to October 2010. In addition, geomorphological and instream habitat changes in the river between the two catchment areas were recorded, as well as the condition of stream crossings and their linkage to stream networks in the afforested catchment. The SASS5 results revealed that stream conditions at the upper unimpaired site were significantly better, visibly and statistically (p < 0.05) than conditions at the lower site within the forestry plantation. In addition, there were noteworthy changes in the catchment hydrology, the geomorphology and instream habitat between the natural and afforested catchments. Road network densities in commercial forests are mostly considerably higher than suggested in literature and exceed stream network densities. Roads increase the surface area for interception of rainfall and the runoff from this high density of roads results in modification of the catchment hydrology, geomorphology and instream habitat of receiving streams. This physical change to the receiving streams is one of the main reasons for the deterioration in SASS5 results, disproving the hypothesis that road networks in forestry areas have no impact on receiving aquatic ecosystems. Commercial forestry in South Africa needs to improve their road planning, layout, management and maintenance to reduce these environmental impacts. In doing so, the road network density will be reduced with considerable environmental and economic benefits.

This study’s main goal was to evaluate Bacillus subtilis inoculation and mine water irrigation effect on germination, growth, nodulation, physiology and shoot/grain quality of cowpea genotypes exposed to extreme climatic conditions (elevated temperatures). The first experiment evaluated the interactive effect of Bacillus subtilis (BD233) inoculation and elevated temperature on germination indices and plumule lengths of three genotypes (Asetanapa, Soronko and Nyira) of cowpea. The results showed that interaction between B. subtilis (BD233) and temperature significantly (p<0.05) influenced the germination indices (germination percentage (G%), germination index (GI) and germination rate index (GRI)) and plumule length of cowpea seedlings and genotype responses were significantly different. At elevated temperature (35oC), inoculation with B. subtilis (BD233) enhanced seed germination and growth of cowpea. The second experiment evaluated the effect of temperature on growth and nutritional content of cowpea incubated for seven days in a growth chamber. The results showed that when cowpea genotype, Soronko, was incubated at different temperature regimes, the whole plant biomass, shoot carbon and crude protein contents were significantly affected with temperature increases at all three stages of the plants’ life cycle. The results suggest that the pre-flowering (40 DAP) and flowering (90 DAP) stages of cowpea compared to post-flowering (123 DAP) are more susceptible to elevated temperatures (30-35oC). The third experiment evaluated Bacillus subtilis inoculation and mine water irrigation effect on growth, nodulation, physiology and nutritional content of cowpea under glasshouse conditions. The results revealed that the interaction of B. subtilis (BD233) inoculation and mine water (75% AMD) irrigation was significant for the growth, nodulation, stomatal conductance, chlorophyll contents and shoot/grain nutritional quality of cowpea genotypes. In comparison with control, generally, B. subtilis inoculation enhanced the growth, nodulation and yield of all tested cowpea genotypes and irrigation with mine water significantly influenced the mineral contents in both shoot and grain of cowpea. Taken together, findings in this study have implications for cultivation of cowpea, an important candidate for food/nutrition security in Africa, under future climate change scenarios. / Environmental Sciences / M. Sc. (Environmental Sciences)

A prospective ecological risk assessment method was developed evaluating the cumulative probabilistic impact of chemical stressors to aquatic organisms. This method was developed in response to the need to evaluate the magnitude, duration and episodic nature of chemical stressors on aquatic communities under environmental exposure scenarios. The method generates a probabilistic expression of the percent of an ecosystem's species at risk from a designated chemical exposure scenario.