Academic literature on the topic 'Olifants River'

The Olifants River Bridge B3611 carries the N11 over the Olifants River, just North of the Loskop Dam. This structure was originally built in 1979 and was recently widened as part of the South African Roads Agency Limited (SANRAL)’s upgrade to the N11. At the time of design, very little was known about the bridge as no ‘As Built' drawings were available. Due to the remote locality of the structure, exploratory investigations were reserved until the construction phase. The final design solution was therefore amended during the construction phase in order to account for the reinforcement found within the structure. In addition to the heavier dead weight of the new widened deck, the bridge would be required to carry higher loads under modern loading codes. Widening works included new widened cantilevers with new reinforced concrete balustrades, tying into existing reinforcement. Strengthening for bending was provided to the main deck beams by means of longitudinal FRP plates epoxied to the soffit. Transverse pierhead strengthening using DYWIDAG bars was installed to counter increased moments, and pier strengthening using a reinforced concrete jacket was implemented to strengthen the piers. Durability concrete was specified in accordance with current SANRAL regulations and the durability performance of the concrete, even in this remote location was excellent. This paper summarises the work that was completed as part of this project.

Abstract. Rivers in the Kruger National Park, eastern South Africa, are characterised by bedrock-influenced "macrochannels" containing variable alluvial thicknesses and riparian vegetation assemblages. Evidence from the Sabie and Olifants rivers suggests that flows up to moderate floods (<3500 m3 s−1) tend to result in net alluviation, with sediments gradually covering the underlying bedrock. More extreme floods strip alluvium and erode bedrock, effectively exerting the primary control over long-term river morphologic development. On the Olifants River, post-flood aerial LIDAR imagery reveals that the 2012 extreme flood (~14000 m3 s−1) resulted in extensive stripping of stored alluvial sediment, exposing and eroding the underlying weathered bedrock. On the Sabie River, preliminary optically stimulated luminescence ages for remnant alluvium are all less than 1000 years, highlighting typical timescales of sediment storage. Together, these results suggest that while periods of general alluviation occur on these systems, long-term river development results from extreme flood-generated bedrock erosion.

The tributaries of the Olifants River draining the Cedarberg Mountains in the Western Cape are well known for their diverse fauna of endemic freshwater fish. Aquatic ecosystems in the region have also been identified as being particularly important in terms of ecosystem conservation. Recent surveys of aquatic macroinvertebrates have indicated that the region is rich in Trichoptera, with a number of regional endemic species, some of which are not recognizable as known described species. The distribution of certain species appears to be confined to either the arid east-flowing tributaries of the Doring River or else the wetter west-flowing tributaries of the mainstream Olifants River.

Socioeconomic development objectives are integral to the integrated river basin management initiatives in several river basins around the world, including the Olifants River Basin of South Africa. All viable strategic water management alternatives are expected to contribute towards such, usually predefined, socioeconomic objectives in addition to other hydrological and ecological objectives. An assessment of the relative merits of different alternatives becomes imperative to trace the respective contributions of the alternatives to such objectives and thus to identify the best-bet and most agreeable alternative from a multi-stakeholders' perspective. This paper reports key findings from application of a methodology for this purpose in the Olifants River Basin of South Africa by (a) establishing a link between water management indicators and socioeconomic objectives, (b) assessing the potential socioeconomic implications of various water management alternatives and (c) rank ordering the identified alternatives against the socioeconomic objectives based on multi-criteria decision analysis techniques.

Exploratory modelling of the impact of gold mining on groundwater in a strategic water area of South Africa was undertaken. A systems dynamics (SD) model was developed to simulate the impact of gold mining on water quality, focusing on groundwater contamination risk, within the context of competing developmental priorities around water resource development and the socio-economic gains from gold mining. The model also identified interventions to minimise the impacts by the year 2040. The study area was the Blyde River Catchment (BRC), which is part of the Olifants Water Management Area in South Africa. This area is an important contributor, currently and in the future, to freshwater flows and groundwater in the Olifants River Catchment, which is one of South Africa’s most economically important catchments. The model development process included a causal loop diagram­–based problem conceptualisation, followed by the drawing of stock-flow diagrams and the determining of model parameters based on a combination of background literature, data from environmental impact assessments, and from the national Department of Water and Sanitation. The model showed the potential environmental risks of gold mine wastewater production and interventions to minimise these risks. The most effective intervention identified to reduce the risk of groundwater contamination was the development and use of synthetic-lined tailings dams. The baseline simulation result of sulphate loading of 5430 t/year can be reduced by 3070 t/year to give a simulated sulphate load of 2270 t/year in 2040 using this intervention. In comparison, the simulated wastewater recycling intervention only reduced the sulphate load to 4630 t/year and the wastewater treatment interventions to 3420 t/year. This project contributes to the exploratory modelling of an understudied region of the Olifants River Catchment that is a crucial provider of freshwater flows to the Olifants, which is threatened by increasing gold mining in the upper BRC. The SD model highlighted the importance of protecting the dolomitic aquifers in the BRC for the long term sustainability of the catchment, which is particularly important if groundwater development occurs.

This study investigated the impact of exotic Tamarix species on vascular plant biodiversity in riparian ecosystems in the Western Cape Province, South Africa. Vegetation was sampled, using 5 m wide belt transects, along the Leeu, Swart, and Olifants riparian areas, which had varying invasion intensities. Each transect was split into three zones (Zone 1: 0–15 m; Zone 2: 15–35, and Zone 3: >35 m), which were identified at each site based on species composition across each riparian zone. Woody plant species were identified, counted, and their heights measured within the transects that were laid out from the waterpoint (Zone 1) outwards (Zone 2 and 3). Herbaceous aerial cover (HAC) was determined subjectively and objectified using the Walker aerial cover scale. Leeu River had the highest species richness (Dmg = 2.79), diversity (H′ = 2.17; −lnλ = 1.91; N1 = 8.76 and α = 4.13), and evenness (J′= 0.80). The Swart River had the lowest species richness, which declined from Dmg = 1.96 (Zone 1) to Dmg = 1.82 (Zone 3). Exotic Tamarix species ranked in the top three most abundant woody vascular plant species along the Swart and Olifants rivers, where they ranked first and third, respectively. The Jaccard’s and Sorenson’s coefficients of similarity indicated that species differed greatly between the different sites, x¯ < 27% for both indices. The indices also indicated that the Swart River had the lowest level of species distinctness between zones (x¯ > 80%) while the Leeu River had the highest level of species distinctness (x¯ < 50%) between the different zones. These findings suggest a possible displacement of herbaceous and woody tree species by exotic Tamarix invasion, inter alia, a decrease in ecosystem functions and services associated with the loss in biodiversity, as well as significant bearings on the agricultural ecosystem by reducing the faunal diversity such as crop pollinators, inter alia.

Includes bibliographical references.
Small-scale fisheries are increasingly seen as complex socio-ecological systems, requiring alternative management approaches. These new approaches to natural resource management advocate the inclusion of resource users in all aspects of management, including monitoring. Research suggests that involvement of local resource users in resource monitoring is beneficial as it promotes local empowerment, community stewardship and contributes to social and resource sustainability. This study aims to contribute knowledge about the nature and effectiveness of a community-based fisheries monitoring system at the Olifants River estuary in South Africa and documents lessons learned. This research reports on the revision and revitalisation of an existing community monitoring program operating at the Olifants River estuary and presents the results of data gathered from this one year monitoring program. It also compares these results with data gathered from previous years when the monitoring system was operational. Finally, the strengths and weaknesses of the community monitoring system are discussed. A participatory research approach was followed by employing members of the Olifants River community as catch monitors and working closely with the fishers and monitors to better understand their perceptions of the strengths and weaknesses of the monitoring system. Findings of this research suggest that despite weaknesses in the community monitoring system, the data gathered provided useful information about the catch effort trends for the fishery for the year under consideration and also enabled some comparisons of selected fisheries indicators with previous data to be made. These comparisons suggest that catch per unit effort for the target species, harder (Liza richardsonii) is stable and there is no indication of overexploitation of this resource. A key weakness of the monitoring is that it is ad hoc and funding is insecure. Due to poverty levels in the community, local monitors may take up short-term employment opportunities in the community and thus neglect their monitoring responsibilities. This means that the data sets are not comprehensive. Key strengths include the fact that it is simple, cost effective and can be implemented by community members. Furthermore, local involvement in resource monitoring builds capacity and skills as well as local empowerment. Finally, this research contributes to knowledge that can inform the implementation of community monitoring programs proposed by the recently published Small-scale fishing policy of South Africa. Key Words: Small-scale fisheries; natural resource management; participation, community monitoring, local empowerment.

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.

This thesis investigates changing patterns of landscape use throughout the Earlier (ESA), Middle (MSA) and Later Stone Ages (LSA) in the Olifants River Valley in the Western Cape, South Africa. Stone Age surface assemblages are all too often neglected in favour of stratified, datable cave sequences, overlooking important insights into changing behavioural patterns at a broader scale. The Olifants River Valley offers the opportunity for integrating a rich surface lithic record with excavated rock shelter occupation dating from the LSA and extending back into the early part of the MSA. This thesis approaches Stone Age landscape use with reference to a hypothesis proposed by Hilary Deacon, framing the MSA within the context of earlier and later patterns of behaviour. Based on observations from sites across South Africa, Deacon described ESA landscape use as stenotopic, occupying a narrow ecological niche focused on permanent water sources, and LSA landscape use as eurytopic, making use of a much broader range of habitats but with a specific focus on rock shelters as domestic sites. Deacon suggested that the intervening MSA, in its later stages, shows a pattern that anticipated LSA landscape use, with an increasing emphasis on caves and a wider-ranging exploitation of resources across different environmental zones. Surface surveys were carried out in the Olifants River Valley, mapping temporally diagnostic artefacts and their association with different topographic features. In this thesis, I test Deacon's model and show that it can be applied to the study area, observing distinctive preferences for certain sites and raw materials, and approaching changes in patterns of artefact discard from a technological perspective.

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.

Includes bibliographical references (leaves 99-105).
Trace elements have received increased attention since the mid-1900's. Although some studies have investigated trace element accumulation as a result of urban expansion in the Western Cape, South Africa, few have catalogued the accumulation and behavior of trace elements resulting from agricultural practices. This study investigates the distribution and behavior of trace elements for the Olifants and Berg river catchments by focusing on the sediments of the estuaries. The dominant industry in both catchments is agriculture and there exists relatively little urban sprawl. Two sediment samples taken from the offshore mud belt in the vicinity of the two river mouths were also analyzed. The sediments were analyzed for trace elements using inductively coupled plasma mass spectrometry (ICP-MS), major elements using X-ray fluorescent spectroscopy (XRF), total sulfur using XRF, total and organic carbon using a C:H:N analyzer, and grain size analysis was performed (>62 μm, 38-63 μm, 2-38 μm, <2μm). The mud belt cores were dated using 14C dating. Estuarine surface waters were analyzed for trace elements, pH, dissolved oxygen (DO), electrical conductivity (EC), and temperature. The trace elements arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) were focused on. The trace element concentrations in the sediments were compared with those of soils that occur in the study area, as well as their parent materials, to determine background concentrations. The concentration profiles of elements with respect to depth are compared with natural deposition rates to recognize signs of recent enrichment of individual trace elements. Inter-element comparisons are made in an attempt to determine speciation. Comparison between the estuarine and mud belt sediments were made to assess the estuaries ability to filter fluvial trace elements, as well as to determine the sediment contributions of the Olifants and Berg rivers to the mud belt. Statistical analysis was performed to"group sediment populations Trace element and organic matter concentrations showed strong positive correlations with fine-sized particles. The mud belt sediments displayed considerably more OC than the estuarine sediments. The trace elements appear to associate predominantly with clay minerals (alumino-silicates), Fe/Mn oxides, and organic matter. Trace element correlations with S and carbonate carbon were also observed. Comparison with estimates of natural deposition rates and compositions of soils occurring in the catchments did not suggest an anthropogenic pollution input. From the data available the estuarine and Mud Belt sediments appear enriched in Cd, Cu and Zn in comparison to the background soils. The estuaries seem to effectively trap Zn and Pb, but do not capture As well. Statistical analysis suggest that, of the rock types considered, the sediments of the Olifants and Berg river estuaries and those of the off shore mud belt are most similar to sediments derived from the Malmesbury and Ecca Groups. The Olifants and Berg rivers are important sources of water for the farming community, as well as for municipal use in the Western Cape. Based on this investigation of the estuarine waters and sediments the rivers appear to be in good health in regards to trace element concentrations.

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

Thesis submitted in partial fulfilment of the requirements for the degree Master of Technology: Nature Conservation in the Faculty of Applied Sciences at the Cape Peninsula University of Technology
In the Cape Floristic Region the Olifants- Doorn River (ODR) system is a known biodiversity hotspot in terms of endemic freshwater fish. Eight of the 10 described native freshwater fish species are endemic to this river system. One of the main threats to these fish is predation by introduced predatory fishes. Three species of alien invasive black bass (Micropterus salmoides, Micropterus dolomieu and Micropterus punctulatus) were introduced into the ODR system during the 1930s but prior to this study, their distribution and impacts had never been quantified on a system-wide basis. This study aimed to clarify the current distribution, distribution barriers, predatory impact and best management options for black bass in the ODR system. This was achieved by conducting a system-wide survey of 578 km of stream covering 41 tributaries in the ODR system. Black bass presence was tracked upstream within each tributary to its uppermost distribution point where physical barriers preventing further spread were identified and described. Fish species composition, abundance and size were recorded directly above and below these barriers to quantify black bass impact on the native fish. This research demonstrated that since introduction, natural and human assisted dispersal has facilitated not only the establishment of black bass in the Olifants and Doring main streams but also facilitated the invasions into 22 tributaries. Based on survey results it was estimated that 81.5 % of the ODR system that was previously occupied by native cyprinids is now invaded by black bass. Assessments of native fish abundance and size distribution above and below black bass invasion barriers demonstrated that in invaded tributaries only adults of larger cyprinids (Labeo seeberi, Labeobarbus capensis and Barbus serra) were able to co-occur with black bass species. Smaller fish such as juvenile L. seeberi, L. capensis and B. serra and native minnows (Barbus calidus, Pseudobarbus phlegethon and Barbus anoplus) were absent from the black bass invaded reaches. The findings of this catchment scale study are consistent with findings from other studies in the region. As a result, most native fishes are now restricted to streams above the natural barriers that limit the upstream invasions of black bass. Black bass eradication from invaded reaches is therefore necessary for habitat restoration. Effective eradication will however depend on the presence of barriers to prevent re-invasion from downstream sources. To better understand what constitutes the nature of such barriers, this study characterised the natural barriers that inhibited black bass invasions in 17 tributaries. Natural barriers comprised of 15 waterfalls, two cascades and one chute ranging in height from 0.49 m to 3.5 m with an average vertical drop of 1.21 ± 0.67 m. These findings suggest that black bass have poor jumping abilities and the recommended height of artificial barriers as part of a black bass management program should be between 80 and 100 cm depending on the size of the tributary. As a result, the presence of natural barriers or the construction of artificial barriers to prevent black bass invasions is considered a vital component of native fish conservation projects. Finally, the study assessed the feasibility of black bass eradication from the 22 invaded tributaries in the ODR system based on eight criterion covering aspects of biological, physical, anthropogenic and logistical importance. This assessment showed that effective eradication was most likely only feasible in seven tributaries. Prioritisation of these seven tributaries for black bass eradication based on the threatened status of the resident native species, the land-use in the respective catchments and the tributary length available for rehabilitation indicate that the Breekkrans, Biedouw and Thee Rivers should receive the highest priority.

Magister Scientiae - MSc (Environ & Water Science)
The upper Olifants River catchment, situated in Mpumalanga Province, South Africa, is one of the main sources of water for this region. This region face challenges to guarantee future water security due to intensive land use activities e.g. mining, energy production, and agriculture activities. South Africa is the sixth largest producers of coal in the world and the Witbank (eMalahleni) coal fields, situated in the catchment, represents the largest conterminous area of active coal mining in South Africa. The second largest irrigation scheme (Loskop dam Irrigation Board) is also found below the Loskop Dam in the upper Olifants River catchment. The irrigation scheme of + - 480 km of irrigation channels provides water for a R1 Billion export industry of citric fruits to the European Union. Furthermore, the Olifants River in Mpumalanga is also a trans-boundary river that initially flows northwards before curving in an easterly direction through the Kruger National Park and into Mozambique where it joins the Limpopo River before discharging into the Indian Ocean. Although the Olifants River is one of the main river systems in South Africa, it has been described as one of the most polluted rivers in southern Africa, with Loskop Dam acting as a repository for pollutants from the upper catchment of the Olifants River system. Because Loskop Dam is of strategic important for the whole region the aim of the study was to show the implications of poor water quality on the local communities down stream of Loskop Dam that depend on water usage for their livelihood. (1) Developing a modified pollution index for the Loskop Dam, Mpumalanga Province using bioindicator algae species in relationship with water column physico-chemical parameters and national water guidelines as indication of pollution. (2) Analysing the threat of cyanobacteria, microsystin contaminations to crops irrigating by water from the Loskop Dam irrigation canals. (3) Discussing the social economic implication of water pollution on the Loskop Irrigation scheme and its stakeholders.

The outlook for Nile crocodiles in the Olifants River does not look optimistic. Since the increase in capacity of the Loskop and Flag Boshielo Dams, the crocodile population was left with no basking or nesting sites and has declined over the past 30 years. Shortly after the Massingire Dam in Moçambique filled to full capacity an estimated 160 crocodiles died in the Olifants River Gorge, a couple of kilometres upstream from the dam. The Olifants River is acknowledged by many experts as one of the most polluted rivers in South Africa and acid mine drainage, industrial pollution and untreated sewage in the river are all contributing to the poor water quality of the river. Further, the Department of Water Affairs and Forestry acknowledge that water demand already exceeds their capacity to supply and that the situation will worsen considerably in the near future. Aerial surveys of Nile crocodiles in the Olifants River was carried out during December 2005 and November 2009. An average total population of 714 Nile crocodiles were counted and corrected to an estimated 1140 individual crocodiles to eliminate the effects of undercounting. The Kruger National Park and specifically the area of the Olifants River Gorge was found to be one of the preferred habitat areas for crocodiles in the Olifants River as was the Flag Boshielo Dam, the area between the Blyde River and the western boundary of the Kruger National Park and the Olifants River between the Loskop Dam and the Flag Boshielo Dam. Repeated nesting in areas such as the Kruger National Park, the Flag Boshielo Dam and the Olifants River between the Loskop Dam and the Flag Boshielo Dam confirmed that these areas are critically important to the nesting success of Nile crocodiles in the Olifants River. The Elands River was confirmed as an important refuge area for Nile crocodiles in the Groblersdal-Flag Boshielo Dam area of the Olifants River. Surveys revealed an estimated total of only 15 crocodiles in the Loskop Dam and confirmed that no crocodiles in the large (2.1 - 4.0m TL) and very large size class (>4.0m TL) are currently present in the population. Blood biochemistry results indicate that the Olifants River Nile crocodile population probably suffers from chronic inflammation (especially in the Loskop Dam and Olifants River Gorge populations), infectious disease (particularly in the Loskop Dam population but all other sites also showed elevated values), possible inadequate diet and malnutrition (especially during the pansteatitis outbreak of August/September 2008) and are suffering serious immune problems in the Olifants River Gorge. A conservation and management plan is suggested which identifies threats to the continued existence of a viable Nile crocodile population in the Olifants River. Finally, it is suggested that the conservation status and risk of extinction of Nile crocodiles in the Olifants River be upgraded to the Endangered category since it currently complies to the following criteria; EN A2abce; C2a(i) published in the IUCN Red List Categories and Criteria Version 3.1 (IUCN, 2001).
Thesis (PhD)--University of Pretoria, 2011.
Centre for Wildlife Management
unrestricted