Austroglanis gilli and A. barnardi are endemic to the Clanwilliam-Olifants System in the Western Cape, South Africa. The populations of each of these species are considered to be threatened by various anthropogenic activities, which include inappropriate agricultural practice and impacts of alien invasive fish species. The purpose of this thesis was to assess the life-history of these two endangered species in order to contribute to understanding their biology. Such information is vital for the development of strategies for their conservation. Marginal zone and marginal increment analyses from sectioned lapilliar otoliths of both A. gilli and A. barnardi showed a unimodal peak, suggesting a single annulus formation. The oldest specimens of A. gilli and A. barnardi were 12+ and 14+ years, respectively. The growth of A. gilli and A. barnardi was relatively slow and was best described by the von Bertalanffy growth curve as: L, = 131.56(1 - exp(- 0.27(t - 1.18 ))) for male and L, = 113.86(1 - exp(- 0.43(1- 0.74))) for female A. gilli from the Rondegat River. In the Noordhoeks River, growth was L, = 99.67(1 - exp(- 0.53(t - 0.35))) for male and L, = 96.60(1 - exp(- 0.64(t - 0.11 ))) for female A. gilli, and L, =71.02(1-exp(-0.26(1-3.07))) and L, = 69.50(1-exp(-0.36(1 - 1.88))) for male and female A. barnardi, respectively. The average natural mortality for the combined sexes was estimated using catch curve analysis at 0.37 ± 0.12 per year for A. gilli from the Rondegat River, and at 0.71 ± 0.05 and 0.39 ± 0.04 per year for A. gilli and A. barnardi from the Noordhoeks River, respectively. For A. gilli in the Rondegat River, the first maturity was estimated at 3.3 years (97.3 mm SL) for males and 3.1 years (94.3 mm SL) for females. In the Noordhoeks River, the first maturity for A. gilli was estimated at 2.0 years (71.9 mm SL) for males and 1.7 (66.4 mm SL) for females, and for A. barnardi at 2.0 (55.0 nun SL) for males and 2.9 years (58.9 mm SL) for females. Maturity corresponded closely to the asymptotic sizes from the von Bertalanffy curves, suggesting a shift in energy use from somatic growth to gonad development. Macroscopic assessment of the state of gonads, the Ganado-somatic index and histological examinations revealed that both A. gilli and A. barnardi have a single spawning season. The presence of oocytes in different stages of development in each of the ovaries of mature females collected between November and January suggested asynchronous, iteroperous serial spawning. The resorption of yolk was observed from ovaries collected between February and March and no vitellogenic oocyte was visible from ovaries collected between April and August. A similar trend was observed for males, with spermatozoa filling the lumen between November and January and some residual spermatozoa being present in the lumens soon after the breeding season. Spermatocytes and spermatids were dominant in the testes until October. An Index of Relative Importance revealed that A. gilli feeds predominantly on the benthic macroinvertebrate larvae of Ephemeroptera (particularly Baetidae), Diptera (particularly Chironomidae and Simuliidae) and Trichoptera. Austroglanis barnardi feeds predominantly on dipteran larvae (particularly Chironornidae and Simuliidae). Chi square contingency tables showed a significant difference in the dominant prey items of A. gilli and A. barnardi in the Noordhoeks River (X₂= 53.79, d.f. = 4, p > 0.001) and A. gilli between Rondegat and Noordhoeks rivers (x₂ = 34.74, d.f. = 4, p > 0.001). The Spearman's rank correlation test showed no shifts in the diet of A. barnardi from Noordhoeks River and A. gilli from Rondegat River with a change in size and season (p>O.OS). However, there was a shift in the diet of A. gilli from the Noordhoeks River which could suggest a distinct patchiness of benthic macroinvertebrates between the riffle feeding areas used by juveniles and other biotopes used by adults. The occurrence, in stomach contents, of other prey items from a wide variety of taxa and the presence of allochthonous material from the terrestrial environment could suggest an opportunistic feeding guild for both Austroglanis species. The life-history traits of A. gilli and A. barnardi, which are charaterized by slow growth, long life span and low relative fecundity, indicate that both species are relatively precocial and K-selected. The population of a precocial species is relatively stable and if population numbers were to be greatly reduced, they would require a long time to rebuild. An urgent conservation intervention is therefore recommended for Austroglanis spp. so as to maintain the diversity of populations within these species. The creation of protected river reserves and raising public conservation awareness may minimise activities that result in altered river hydrology and the destruction of complex benthic habitats.

Thesis (M.Sc. (Zoology)) -- University of Limpopo, 2020 / Water pollution has been one of the major concerns all over the world for at least the past two decades. In South Africa, the Olifants River System is one of the most polluted river systems. Anthropogenic activities being carried out within the Olifants River Catchment area pose threats to the aquatic ecosystem. The Upper and Middle catchments are being characterised by intensive mining, industries, agricultural practices and inadequate sewage treatments. Thus, the aim of this study was to investigate the influence of mining activities on the water quality and health status of the Steelpoort River, a tributary of the Olifants River System. This was achieved through assessing the quality of water by analysing physico-chemical parameters, macro nutrients and metals at four selected sites, determining the response of macro invertebrate assemblages to water quality using the South African Scoring System (SASS) version 5 and determining the diversity of fish using the Fish Response Assessment Index (FRAI). Sampling of water, sediment, macro-invertebrates and fish was done seasonally (August 2017 – May 2018) at four selected sites. Site 1 and site 2 were located upstream while site 3 and site 4 were located midstream and downstream respectively. Water and sediment samples were analysed by WATERLAB (PTY) LTD by means of Inductively Coupled Plasma Optical Spectrometry (ICP-OES). Macro-invertebrates were sampled following the SASS protocol. Macro-invertebrates were identified, counted and recorded then released back to the river. Fish were sampled following the FRAI index protocol. The results obtained indicated that the system variables; pH, water temperature, dissolved oxygen and total dissolved solids fell within the target water quality range (TWQR) for aquatic ecosystems. However, some concentrations of macro-nutrients recorded were above the TWQR. These include ammonium at site 3 and nitrogen at sites 2, 3 and 4 which indicated that there was a variation in the influx of macro-nutrients into the river at different river sections. The higher concentrations of ammonium and nitrogen may adversely affect the functioning and survival of biological communities. The metal results indicated that most metals (As, B, Ba, Cd, Cu, Pb, Ni and Cr) fell within the recommended water and sediment quality guidelines (DWAF 1996c; CCME 2012). Chromium concentrations recorded in sediment were above the sediment quality guideline at all the selected sites (CCME 2012). Iron and Zn were also above the guideline values at all selected sites. In terms of physico-chemical parameters and metal concentrations indicated that the water quality of the Steelpoort River was fairly good. The macro-invertebrates were also analysed; their abundance, distribution and family richness indicated that there was a deterioration of water quality from upstream to downstream which may be an indication of increase in influx of pollutants and modifications in the stream such as flow, cover and microhabitat. The highest macro invertebrate abundance and richness was at site 1 while the lowest was at sites 3 and 4. Site 3 was highly modified while site 1 was the least modified site. The Ephemeroptera, Plecoptera and Trichoptera index (EPT) and Ephemeroptera, Plecoptera and Trichoptera/Chironomidae ratio (EPT/C ratio) analysis also confirmed that the water quality of the Steelpoort River is deteriorating from upstream to downstream. Site 1 had the highest value of EPT while site 2 had the highest value of EPT/C. Site 3 had the lowest value for both EPT and EPT/C ratio. The higher EPT and EPT/C ratio indicate the presence of highly sensitive taxa. The Canonical Correspondence Analysis (CCA) indicated a strong correlation between metals (Pb, Cr, Mg, As and Se) and macro-invertebrates (Pleidae, Ecnomidae, Athericidae, Synlestidae, Lestidae and Pyralidae). The SASS 5 results also indicated deterioration of water quality from upstream to downstream with the highest values of SASS score and Average Score Per Taxon (ASPT) being recorded at site 1 followed by site 2 while the lowest SASS score and ASPT were at site 3 followed by site 4. The use of fish as biological indicator also supported the same pattern of water quality deterioration and influx of pollutants which was previously indicated as increasing from upstream to downstream of the Steelpoort River. Site 1 had the highest fish abundance, while site 4 had the lowest fish abundance. However, the fish species richness was highest at site 4 while the lowest species richness was at site 1. The Shannon Weiner Diversity Index also supported that site 4 had the highest fish species richness while site 1 had the lowest species richness. The FRAI results indicated that different sites were in different Ecological Categories (EC). The ECs showed a trend from higher EC category upstream to lower EC category downstream. Site 1 had an EC of C followed by site 2 with an EC of C/D, site 4 with EC of D and then site 3 with the lowest EC of D/E. This might serve as an indication of decrease in habitat availability, increase of pollutants input and increase in stream modification. The CCA showed a weak correlation system variables and fish species. However, a strong correlation was observed between most metals and most fish species with the exception of Mesobola brevianalis Boulenger, 1908, Chiloglanis pretoriae Van Der Horst, 1931, Labeobarbus marequensis Smith, 1841 and Enteromius neefi (Greenwood, 1962). In conclusion, the water in the Steelpoort River is still in relatively good condition. However, increasing mining, industrial and agricultural practices in the catchment area results in increase of pollutants input into the river system. All the four selected sites were contaminated to some degree, with site 3 being the most affected site and site 1 being the least affected site. For this reason, it is important to continuously monitor the health status of the Steelpoort River and to educate the nearby communities who rely on this river for water supply about the quality of the water from the Steelpoort River. / DSI-NRF SARCHI (Ecosystem Health)

Water availability in Southern Africa is highly variable both in time and space, thereby exposing the region to high risks in water availability. This is further compounded by numerous human activities which have significant impact on water resources. The brunt of the risks associated with water scarcity is particularly heaviest on resourceconstrained farmers who depend largely on rain-fed agriculture for subsistence. With continuously increasing demands on the water resources, the need for a better understanding of the hydrological systems becomes crucial as it forms the gateway for providing reliable information for managing water resources. It is also increasingly becoming more important to address land and water linkages because land use decisions are water use decisions. Operational hydrology provides an insight into the effects of man-made changes, the foreseeable hydrological characteristics at a given site, and the long-term prediction of the future hydrological effects of human activities. This provides for a more holistic approach in managing land and water resources as well as the impact of land use on partitioning rainfall into streamflow. This report discusses the application of the SWAT model to the B72E - F quaternary catchments in the Olifants Water Management Area to assess streamflow generation and the effects of human-environment interactions on the hydrology. Results show an expected correlation between land cover and the hydrologic response where an increase in land cover corresponds to a reduction in the streamflow. Range grass shows a higher reduction in the streamflow followed by forestry with arid land giving the highest increase in streamflow. Prediction in the similar neighbouring and ungauged B72A catchment gives a MAR of 68mm. Additionally, a rigorous analysis of the concepts of a local hydrological model, HDAM, is done with respect to rainfall which is the main driver of the model. Modifications of some of the relationships used in the model are suggested with the potential of streamlining the model and making it more applicable in the region.

Thesis (Ph.D (Zoology)) --University of Limpopo, 2018 / Freshwater ecosystems are the most threatened systems globally, suffering from channel modification, over extraction of water and, of particular concern, pollution. In South Africa, Olifants River is categorised as the third most polluted river system. Acid mine drainage seeping from derelict and abandoned mines has been described as the primary stressor in the upper Olifants catchment. The increase of metal concentration in the water, sediment and fish tissues has been evident over the past few decades. As a result, there has been an increasing concern regarding the effects of increased metal concentrations on the health of fish and the safety of communities consuming fish from the polluted Olifants River system. This study used enzymatic and histopathologic biomarkers to assess the physiological response of Oreochromis mossambicus and Labeo rosae to environmental contaminants. The study further investigated the metal accumulation trend of across different fish tissues and assessed the edibility of O. mossambicus and L. rosae from Loskop and Flag Boshielo dams. Water, sediment and fish samplings were carried out concurrently during low flow and high flow seasons in 2014. Water and sediment sampling were done at the inflow, middle and dam wall. A minimum of 10 fish specimens for each species were collected from Loskop and Flag Boshielo dams during each sampling. For bioaccumulation analysis, liver, gill and muscle tissues were dissected out, wrapped with aluminium foil and frozen. Frozen samples were sent to SANAS accredited laboratory for metal analysis. For Histopathology, tissues were fixed in 10% neutral buffered formalin prior processing. Tissue processing was done at the Pathology laboratory of the University of Pretoria, Onderstepoort campus. For biomarker analysis, liver and brain tissues were fixed in liquid nitrogen in the field and transferred to the -80°C biofreezer at the University of Limpopo, Biotechnology Unit laboratory. Metal concentrations in the muscle tissue were used to calculate hazard quotient for human health risk assessment which was based on the assumptions that an adult weighting 70 kg consume 150 g portion once per week. Alkaline pH was observed in the water throughout the study. Most water constituents were within the guidelines at both dams. The water at Flag Boshielo Dam was oligotrophic with Loskop Dam showing mesotrophic conditions. Concentrations were below detection level for most metals; however, significant concentrations were recorded in the bottom sediment. Although Loskop Dam is being described as a repository for pollutants from the upper Olifants catchment, no significant differences (p>0.05) were observed for metal concentrations in sediment between the two dams. Coinciding with sediment metal concentrations, liver, gills and muscle have shown notable concentrations for both species at Loskop and Flag Boshielo dams. The common trend of liver accumulating higher metal concentration followed by gill and muscle (liver>gills>muscle) was observed for most metals on O. mossambicus and L. rosae at both dams. In contrast, lead, strontium and manganese showed higher concentrations in the gills. Muscle exhibited lowest concentrations for most metals. Remarkable trends on the activities of biomarkers, lactate dehydrogenase (LDH), glucose-6-phosphate dehydrogenase (G6PDH), glutathione-S-transferase (GST) and acetylcholinesterase (AChE) were detected for both species at Loskop and Flag Boshielo dams. Labeo rosae population have shown a significantly high (p<0.05) LDH activities at Loskop Dam and no significant difference (p>0.05) was observed for Oreochromis mossambicus. Glucose-6-phosphate dehydrogenase activities exhibited no significant difference (p>0.05) for both species between the two dams. Labeo rosae have shown a significantly high (p<0.05) GST activities at Loskop Dam whereas Oreochromis mossambicus exhibited no significant difference (p>0.05) between the two dams. Acetylcholinesterase (AChE) has shown no significant difference (p>0.05) for both species between the Loskop and Flag Boshielo dams. LDH, G6PDH and GST activities have shown relationship with metal concentrations, which makes them good biomarkers of metal exposure.The condition factor indicated that overall conditions of O. mossambicus and L. rosae from Loskop and Flag Boshielo dams were good. Hepatosomatic index results were not conclusive. Most histopathological alterations were recorded on both species at both dams, but with different magnitude of severity. Regressive changes were more prominent in the liver and gills of both species at Loskop and Flag Boshielo dams followed by progressive change. Gills of Oreochromis mossambicus exhibited moderate modifications (score >20) at Loskop Dam and slight modification (score <20) at Flag Boshielo Dam. Labeo rosae populations have shown slight modifications (score <20) in the gills at both dams. Both species have shown significant difference (p<0.05) on the gill index between the two dams. Liver index has also exhibited significant difference (p<0.05) for each species between Loskop and Flag Boshielo dams. Slight modifications (score <20) were observed in the liver for both species at Loskop and Flag Boshielo dams. Both species have shown to accumulate metals within their tissues with liver accumulating higher concentration for most metals, followed by gills and muscle, respectively. Although muscle showed to accumulate lesser metal concentrations, it still raise a serious concern as it is the tissue consumed by human. Lead, chromium, cobalt and antimony concentrations have been the only metals of concern in this river system over the past few years; nevertheless, the present study has shown that other metals viz. arsenic, silver and selenium have exceeded international levels for safe consumption. Given the metal concentration trend reported over the past two decade in fish tissues, there is a need for urgent intervention to address the acid mine drainage problem to ensure sustainable development of the Olifants River and safety of communities depending on it for their livelihood. / NRFand RAD

M.Sc. (Zoology) / The catchment area of the Olifants River is being subjected to increased agricultural and mining activities, industrial development and urbanisation. As a result of this, the water quality 'of the Olifants River and some of its tributaries (e.g. Selati River) has been deteriorating since 1983. This causes reason for concern as one of the downstream water users in the Olifants River catchment is the Kruger National Park, which requires of good quality to sustain its terrestrial and aquatic ecosystems It was therefore necessary to determine what extent activity midstream-or--tlie I Olifants River, especial y in the Phalaborwa area, influenced the water quality of the Olifants River. In this study, an evaluation was done of the water quality (physically and chemically of the Lower Olifants River inside of the Kruger National Park, as well as the Lower Selati River, a tributary of the Olifants River which flows through the Phalaborwa area. Special attention was paid to the metal concentrations in the water, sediment and fish. Water and sediment were sampled every alternate month from April 1990 to February 1992 at six sampling sites along the Lower Olifants River and one in the Selati River. Standard methods were used to determine the physical and chemical characteristics (e.g. pH, TDS, etc.) of the water. The fish species Barbus marequensis was also sampled every alternative month, but only at three sampling sites along the Olifants River and one in the Selati River. Organs and tissues that were dissected, included the gills, fat, liver, gonads, gut, muscle, skin, blood, vertebrae, kidney and bile, as well as the gut contents. In February 1992, additional sampling was performed at Pioneer Dam, a natural reference point used in this study. Atomic absorption spectrophotometry was used in the laboratory to determine the Cr, Cu, Fe, Mn, Ni, Pb, Sr and Zn concentrations in the water, sediment and fish samples. (The water quality of the Selati River was found to be stressful to aquatic life, especially .) with regard to the sodium, fluoride, chloride, sulphate, potassium, total ~dissolved salts 1 and metal concentrations (except strontium). The Selati River also influenced the ': water quality of the Olifants River after the Selati-Olifants confluence. Most of the :. time the water quality of the Lower Olifants River in the KNP did, however, comply With the recommended guideline limits, except for the metal concentrations. The high metal concentrations detected in the water (in some cases sub-lethal levels) indicated some degree of metal pollution, but, due to the hardness of the Olifants River water, conditions were not necessarily toxic to the aquatic life. The accumulated metals in the organs and tissues of marequensis gave a good indication of the metal levels to which the fish were exposed. More metals were taken up by the fish from April 1990 to February 1991 than from April 1991 to February 1992. The various metals were . distributed differently to the tissues of B. marequensis, with the highest zinc concentrations being accumulated by the skin and ovaries; the highest copper and iron by the liver, kidney and gut; the highest chromium and nickel by the blood; and the highest manganese, lead and strontium by the vertebrae and gills. These results afforded guidelines as to the types of tissue which should be sampled as the most suitable for the analysis of the various metals in polluted waters.

Ph.D. / The current study evaluated a bio-monitoring technique developed in the USA by Adams, Brown and Goede, 1993. This project was sponsored by the Department of Water Affairs and Forestry (DWAF), to enable testing of the Health Assessment Index (HAI) under South African conditions. Testing took place in the Olifants River system, one of the most polluted river systems . in South Africa. Initially two river points were tested using Oreochromis mossambicus (Robinson, 1996), Clarias gariepinus (Marx, 1996) and Labeo rosae (Luus-Powell, 1997). The current study re-tested the HAI at the same two sample sites, namely Mamba and Balule in the Kruger National Park, using 0. mossambicus and C. gariepinus respectively. Two additional sites were tested in the upper catchment area, namely Loskop Dam and Bronkhorstspruit Dam. The current study further enabled the comparison of HAI results collected during drought and flood conditions. Results obtained after deployment of the HAI were corroborated using chemical analysis of water, sediment and biota. Water and sediment analysis was carried out by the Institute for Water Quality Studies using standard techniques. Bio-accumulation of aluminium, copper, iron, lead, manganese, nickel, strontium and zinc was assessed in the gills, liver, skin and muscle tissue of sample fish using standard Atomic Absorption Spectrometry techniques. Modifications made to the original HAI involved the inclusion of variable ranking in the assessment of fish parasites, with endo- and ectoparasites evaluated separately. Testing of this parasite hypothesis lead to the development of a Parasite Index component to the HAI. Assessment of water, sediment and fish tissue determined that the Olifants River system is indeed exposed to macro and heavy metal pollutants, which negatively affect aquatic health. Constituents posing the greatest threat are chlorides, fluorides, phosphates, total dissolved solids, copper and iron concentrations. Testing the HAI and parasite hypothesis using C. gariepinus, provided the most meaningful results. During testing of the parasite hypothesis both endo- and ectoparasite numbers conformed to the suggested idea that higher endoparasite numbers will occur at highly impacted areas, whereby ectoparasite numbers will be low. This was particularly evident in the lower catchment area, whereby comparisons between drought and flood conditions were carried out. Subsequent decreases in water quality directly after the flood were noted using water and sediment analysis. This observation reflects the results gathered using the HAT and during testing of the parasite hypothesis at all four sample sites. During statistical analysis of the HAI, using logistic regression analysis, parasite numbers, more specifically endoparasite numbers, were the most indicative of fish health. Environmental stressors (flood conditions) result in immunological responses observed in fish, and are reflected statistically using the HAI as changes in WBC %. It is suggested that endoparasites and WBC % provide the best overall assessment of fish condition. These variables should thus not be eliminated, in order to streamline the HAI evaluation procedures. Testing of this bio-monitoring technique under South African conditions provided meaningful results. This indicates that the HAI can be used to assess water quality, with existing water monitoring programmes further benefiting from its incorporation.

The economic development of South Africa has relied heavily on coal mining and water quality is adversely affected by mining - thus coal mining poses a significant risk to South Africa’s water resources. Ensuring judicious use and management of natural capital is always a complex undertaking but the benefits to the mining industry and society as a whole, derived from thoroughly laid-out plans, a supportive but strict regulatory environment and decision-making processes based on sound, scientific information are immense. Value addition to mining products is important to promote conservation of assets and resources. Using the Olifants Water Management Area as a case study, the chemistry of groundwater associated with coal mining was characterised. General concepts regarding the relationship of geology to water chemistry are surmised. Copyright / Dissertation (MSc)--University of Pretoria, 2012. / Geology / unrestricted

Thesis (MSc)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: Endemic redfin minnows of the Olifants River System are under threat of extinction, mainly because of alien predatory fish, water extraction and pollution. The taxonomic position and biogeography of redfins in relation to other barbs are uncertain. Enzyme electrophoresis was employed to assess genetic differentiation within and among certain Barbus and Pseudobarbus taxa. Fourteen enzymes were routinely recorded from muscle tissue extracts, yielding a differential number of active loci. The latter is due to different ploidy levels. Polyploid species showed fewer loci than the tetraploid or hexaploid number of loci expected just after the polyploidy event. Barbus aenus (hexaploid) expressed 6.2 % of the duplicated loci expected after the hexaploidy event. The tetraploid Pseudobarbus and serrated Barbus spp., expressed 37.5 % and 31.2 % of the duplicated loci expected after the tetraploidy event, respectively. This suggests that the ploidy event in Barbus aenus is more ancient than in the above-mentioned tetraploid barbs. The similar amount of diploidization in Pseudobarbus and tetraploid serrated Barbus spp. investigated, suggests a shared ploidy event between these two lineages. The number of active loci is apparently not a good indication of the ploidy level of African barbs, as hexaploid Barbus aenus expressed less active loci than the tetraploid barbs investigated. Initial screening of allozyme loci yielded fixed allele differences at 22 loci, but polymorphism only at seven. This suggests more potential for delineating species boundaries than for assessing gene flow and genetic diversity of populations. Genetic differentiation within and among populations of Pseudobarbus phlegethon, Barbus calidus and Barbus erubescens were investigated by screening 27 allozyme loci. A clear divergence between Pseudobarbus phlegethon populations from the Olifants and Doring Rivers was found (Nei's unbiased genetic distance = 0.355; F-statistic for subpopulation against the total = 0.877). Preference and adaptation for mountain stream habitat might explain the past isolation and subsequent divergence of Pseudobarbus phlegethon populations between these two rivers. Barbus calidus was genetically homogenous over its distribution (Nei's unbiased genetic distance = 0-0.009; F-statistic for subpopulation against the total = 0.135). It is proposed that Barbus calidus is better adapted than Pseudobarbus phlegethon to disperse through the main stream. The genetic divergence between Barbus calidus and Barbus erubescens (Nei's unbiased genetic distance = 0.063) is characteristic of conspecific populations. There seems to have been a loss of genetic diversity in redfin populations of the Doring River tributaries (heterozygosity = 0-0.01), compared to the redfin populations of the Olifants River tributaries (heterozygosity = 0.01- 0.04). From phylogenetic analysis ofallozyme characters, it seems as if the serrated tetraploid barbs from South Africa is the sister-group of Pseudobarbus, whilst Barbus anoplus was rejected as a sister-species for the latter. Barbus calidus, Barbus erubescens and Barbus serra were found to be closely related to each other. The ancestor of the redfins seems to have been present in the Cape Fold Mountains since at least the late- Tertiary. On the basis of distributional and allozyme information, conservation units reflecting historical divergence, historical gene flow and current gene flow were identified as Evolutionarily Significant Units, Historical Management Units and Current Management Units respectively. The Olifants and Doring River populations of Pseudobarbus phlegethon should be recognized as two distinct Evolutionarily Significant Units. Barbus calidus forms a separate Evolutionarily Significant Unit from Barbus erubescens. Twelve Historical Management Units and nineteen Current Management Units were recognized for redfins of the Olifants River System. The size of Current Management Units should be expanded and secured to prevent loss of genetic diversity. It is recommended that a recovery program of redfins should establish new populations of at least Barbus erubescens and Doring River Pseudobarbus phlegethon Evolutionarily Significant Unit. Centrarchids should be irradicated, as they are the main reason for the decline of red fins. / AFRIKAANSE OPSOMMING: Die endemiese rooivlerkies van die Olifantsriviersisteem word bedreig deur uitsterwing, hoofsaaklik as gevolg van uitheemse roofvisse, water onttrekking en besoedeling. Die taksonomiese posisie en biogeografie van rooivlerkies in verhouding met ander barbusse is onseker. Ensiemelektroferese is gebruik om genetiese differensiasie binne en tussen sekere Barbus en Pseudobarbus taksa te bepaal. Veertien ensieme, wat verskillende hoeveelhede aktiewe lokusse gelewer het, is op roetine basis waargeneem uit spierweefselekstrakte. Die verskillende hoeveelhede aktiewe lokusse wat waargeneem is, is as gevolg van verskillende ploied vlakke. Poliploïede spesies het minder lokusse getoon as wat verwag sou word net na die tetraploïede ofheksaploïede gebeurtenisse. Barbus aenus (heksaploïed) het 6.2% van die gedupliseerde lokusse, wat verwag sou word na die heksaploiede gebeurtenis, uitgedruk. Die tetraploïede Pseudobarbus en saagagtige Barbus spp. het 37.5% en 3l.2% respektiewelik van die gedupliseerde lokusse, wat verwag sou word na die tetraploïede gebeurtenis, uitgedruk. Dit dui daarop dat die ploïede gebeurtenis in Barbus aenus meer histories as in die bogenoemde tetraploïede barbusse. Die soortgelyke hoeveelheid diploïedisasie in Pseudobarbus en tetraploïede saagagtige Barbus spp. wat ondersoek is, dui op 'n moontlike gesamentlike ploïede gebeurtenis tussen hierdie twee evolusionêre lyne. Die aantal aktiewe lokusse blyk nie 'n goeie aanduiding van die ploïed vlakke van Afrika barbusse te wees nie, aangesien die heksaploïede Barbus aenus minder lokusse as die tetraploïede barbusse wat ondersoek is, getoon het. Aanvanklike analisering van allosiem lokusse het vaste alleel verskille in 22 lokusse opgelewer, maar slegs sewe het polimorfisme getoon. Dit dui op moontlike beter potensiaalom spesie-grense vas te stel, eerder as die bepaling van genevloei of genetiese diversiteit van populasies. Genetiese differensiasie binne en tussen populasies van Pseudobarbus phlegethon, Barbus calidus en Barbus erubescens is ondersoek deur 27 allosiem lokusse te analiseer. 'n Duidelike divergensie tussen Pseudobarbus phlegethon populasies van die Olifants- en Doring- riviere is gevind (Nei se onbevooroordeelde genetiese afstand = 0.355; F-statistiek vir subpopulasie teen die totaal = 0.877). Voorkeur en aanpassing vir bergstroom habitat, mag moontlik die historiese isolasie en daaropvolgende divergensie van Pseudobarbus phlegethon populasies tussen hierdie twee riviere verduidelik. Barbus calidus was geneties homogeen oor sy verspreiding (Nei se onbevooroordeelde genetiese afstand = 0-0.009; F-statistiek vir subpopulasie teen die totaal = 0.135). Dit word voorgestel dat Barbus calidus beter aangepas is as Pseudobarbus phlegethon om deur die hoofstroom te versprei. Die genetiese divergensie tussen Barbus calidus en Barbus erubescens (Nei se onbevooroordeelde genetiese afstand = 0.063) is kenmerkend van spesiespesifieke populasies. Dit lyk of daar 'n verlies aan genetiese diversiteit in rooivlerkie populasies vanafdie Doringrivier sytakke was (heterosigositeit = 0-0.01), in vergelyking met rooivlerkie populasies vanafdie Olifantsrivier sytakke (heterosigositeit = 0.01- 0.04). Uit die filogenetiese analise van allosiem kenmerke, blyk dit dat die saagagtige tetraploiede barbusse van Suid-Afrika die sistergroep van Pseudobarbus is, terwyl Barbus anoplus verwerp word as sisterspesie vir laasgenoemde. Dit is gevind dat Barbus calidus, Barbus erubescens en Barbus serra baie naverwant aan mekaar is. Dit lyk asof die voorvader van die rooivlerkies sedert ten minste die laat-Tersiêr in die Kaapse Plooiberge aanwesig was. Bewaringseenhede wat historiese divergensie, historiese genevloei en huidige genevloei voorstel, is geidentifiseer respektiewelik as Evolusionêre Beduidende Eenhede, Historiese Bestuurseenhede en Huidige Bestuurseenhede. Dit is gedoen op grond van verspreidings- en allosieminformasie. Die Olifants en Doring populasies van Pseudobarbus phlegethon moet as twee unieke Evolusionêre Beduidende Eenhede erken word. Barbus calidus en Barbus erubescens vorm aparte Evolusionêre Beduidende Eenhede. TwaalfHistoriese Bestuurseenhede en negentien Huidige Bestuurseenhede is geidentifiseer vir rooivlerkies van die Oifantsriviersisteem. Die grootte van Huidige Bestuurseenhede moet vergroot en beveilig word om verlies van genetiese diversiteit te vermy. Dit word voorgestel dat 'n herstelprogram van rooivlerkies moet poog om nuwe populasies, van ten minste Barbus erubescens en Doringrivier Pseudobarbus phlegethon Evolusionêre Beduidende Eenhede, te vestig. Baars en blouwang sonvis moet uitgeroei word, aangesien hulle die hoofoorsaak is vir die afname van rooivlerkies.

M.Sc. / A comparative study was undertaken in the Olifants River catchment, to determine the water quality at two dam sites, namely, Bronkhorstspruit Dam (control) and Loskop Dam (polluted) in the upper Olifants River system and two river point, namely, at Mamba and Balule in the Kruger National Park, in the lower Olifants River system. Data was obtained during the physical and chemical analysis of water and sediment samples, and during bioaccumulation studies using Atomic Absorption spectrometry, testing for aluminium, chromium, copper, iron, lead, manganese, nickel, strontium and zinc. These tests were conducted on the liver, skin, muscle and gills of Clarias gariepinus. The information collected from Mamba and Balule, was compared with a previous study carried out primarily in the Kruger National Park by Marx, (1996). The study undertaken by Marx (1996) was carried out during a drought period, which allowed for the comparison with results recorded after flooding during the present study. This current research project therefore allowed for the comparison between two different water sources, namely, that of dams and rivers, and under varying environmental conditions. The Aquatic Toxicity index (ATI) developed by Wepener et al. (1992) was employed to facilitate the comparison between the water physical and chemical parameters that were measured, at each sample site, with a single variable being calculated for each sample site per survey. The water quality (ATI values) at the two control sites namely, Bronkhorstspruit Dam and Balule deteriorated substantially after the floods. High water levels due to the floods had a dilution effect on the concentration of pollutants however, toxicants were washed in from upstream and due to surface runoff. The removal of the purifying reed beds upstream of Balule and at the inflow to Bronkhorstspruit Dam, resulted in the release of latent sludge containing metals and organic pollutants into the water column. The ATI value's obtained for the two control points were similar or even higher than those obtained for the two polluted sites namely at, Loskop Dam and Mamba for the autumn and winter sampling periods. During following surveys the water quality at all four sample sites improved, returning to pre flood values by the last survey in summer, namely reflecting similar values as those recorded by Marx (1996) at Balule, Mamba and Loskop Dam for the same period. Sediment concentrations recorded a similar trend to that for water at all four sample sites throughout the study. The bioaccumulation study indicated that the gill concentrations recorded were generally the highest, followed by the liver concentrations. From this one may deduce that gills were the dominant site for metal absorption by the fish, with the excretion of metals also taking place via this route. Liver concentrations are an indication of the activation of protective _mechanisms in the fish sampled, the high concentrations recorded indicate the high physiological response the fish have had to the various levels of exposure. The low concentrations recorded in the muscle indicates the effectiveness of the liver in the detoxification of the fish, indicating that only limited storage of the various metals tested for took place at this site. Skin concentrations were quite high, these concentrations represent the products of an excretory process, which takes place via the skin. The order of concentrations recorded during the present study, were similar to the orders recorded by Marx, (1996) and other authors, however, the order of the skin and muscle concentrations were often reversed. This may be due to the increased excretion of these metals via the skin, resulting from increased exposure to these metals after the floods. Thus the increased exposure

D.Phil. / By virtue of its position on the eastern border of South Africa, the Kruger National Park (KNP) receives the flow of six main riven, of which the greater part of the specific catchment areas are situated upstream from the park itself. The Olifants River has the largest catchment area both in size and in proportion of catchment area beyond the park boundary. Increased competing demand for water by the urban, industrial, mining and agricultural sectors within the catchment boundaries of the Olifants River has focused attention on the ecological water requirements of the river. Of particular concern was the high degree of mineralisation of the Olifants River due to mining activities on the western boundary of the KNP. When one considers the demand for water by the Kruger National Park it is evident that water is required for more than one use, i.e. for potable use, game watering and ecosystem (aquatic and riparian) maintenance. In order to facilitate proper water quality management it is necessary to develop a comprehensive water quality management plan for the river. The development of such a plan requires a thorough understanding of the fate and effects of pollutants in the environment. It is furthermore important to have reliable information on the trends and status of important water quality determinants in these systems. This study was therefore aimed at investigating the metal ecotoxicology of the lower Olifants River and the Selati River, a tributary of the Olifants River which flows through the Phalaborwa area. Water quality is a driving variable in aquatic ecosystems. Full assessment of water quality of the Olifants River included evaluation of the physical, chemical and biological attributes of the system. The difference between the physical/chemical and biological attributes is that the former provide an instantaneous and often specific assessment of the water quality, whereas the latter integrate changes in the system over time. Water and sediment samples were collected bi-monthly from February 1990 to February 1992 at six stations along the lower Olifants River, one in the Selati River and one in the Letaba River. At each of these sites physical and chemical water quality characteristics were measured. Two metal bioaccumulation indicator species, Labeo rosae and Oreochromis mossambicus, were also sampled during the same period at three stations in the Olifants River and at the Selati River sampling station. Two additional surveys were undertaken to reference sites in the KNP (i.e. Pioneer Dam, and Nhlanganini Dam) during February 1992 and April 1992 respectively. Tissue samples (muscle, gill, liver, gonads, fat and blood) were collected and analysed for Cr, Cu, Fe, Mn, Ni, Pb and Zn using atomic absorption spectrophotometry. The routine monitoring of chemical and physical water quality attributes produces large quantities of complex data which are often difficult to interpret. To reduce the complexity, data may be standardised and summarised into an index. The Aquatic Toxicity Index (ATI) that was developed Metal Ecotoxicology in the Olifants River it Summary during this study presented the water quality of all the sampling stations, during each survey as a single value. This value reflected the water quality's suitability-for-use by fish at the different sampling stations. The ATI showed definite temporal and spatial trends in water quality in the Olifants River. The Selati River was the main contributing factor to the poor water quality measured in the Olifants River within the KNP. This was due to high TDS, metal and fluoride concentrations. Deterioration of the water quality was experienced during flood conditions when the turbidities and total metal concentrations increased. The water quality generally increased between summer and winter surveys (February to June). Bioindicators are species used to quantify biologically available level of metals in the aquatic ecosystem. These organisms take up metals from the ambient water and from food, and the concentrations in their tissues (or changes in concentrations) provide a time integrated measure of metal bioavailability. Temporal bioavailability of metals in the tissues of the bioindicators showed similar trends to the water quality. Highest metal concentrations were measured in fish tissue samples collected during flood conditions (December 1990) and during low-flow conditions (June to October). This was attributed to increased exposure due to metal adsorption to suspended sediments during the flood conditions and to increased ambient metal concentrations during lowflow conditions. The distribution of metals in tissues varied based on the uptake, depuration and metabolism strategies for each metal. In general the gill tissue bioaccumulated the highest metal concentrations, with only Cu and Fe occurring in higher concentrations in liver tissue. Significant positive correlation's were found between bioaccumulation in muscle tissue and the other tissues: Space-bulking and time-bulking of results were carried out to elucidate spatial bioaccumulation patterns. The highest bioaccumulation of Cu, Pb and Ni were recorded in samples from the Selati River, whereas Zn and Cr concentrations were the highest in the Olifants River. An equilibrium partitioning (EP) technique was used to integrate bioaccumulation data and metal concentrations in different phases of the water and sediment and produce specific Cu and Zn criteria for the Olifants and Selati rivers. Although there is a multitude of data available for Cu and Zn toxicity and BCF's, the quality criteria produced during this study, for the first time, made use of results obtained under local conditions. The results from bioaccumulation studies carried out in the field can not provide information regarding the potential effects or the risks the metals may pose to the exposed organisms. Therefore the susceptibility of the organisms to metal contamination can be determined using laboratory studies. Physiology is toxicology's closest relative and contributes markedly in assessing the toxicological risk of metals. Bioassays were conducted to determine the uptake kinetics, acid-base disturbances and haematological effects of a metal mixture containing Cu, Fe and Zn on Tilapia sparrmanii. The effects of the individual metals (Cu, Fe and Zn) and different Metal Ecotoxicology