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There is a rapid spread of antibiotic resistance in the environment. However, the impact of antibiotic resistance in drinking water is relatively underexplored. Thus, this study aimed to quantify antibiotic resistance genes (ARGs) and antibiotic residues in two drinking water production facilities (NW-E and NW-C) in North West Province, South Africa and link these parameters to bacterial communities. Physicochemical and ARG levels were determined using standard procedures. Residues (antibiotics and fluconazole) and ARGs were quantified using ultra-high performance liquid chromatography (UHPLC) chemical analysis and real-time PCR, respectively. Bacterial community compositions were determined by high-throughput 16S rRNA sequencing. Data were analysed using redundancy analysis and pairwise correlation. Although some physicochemical levels were higher in treated than in raw water, drinking water in NW-E and NW-C was safe for human consumption using the South African Water Quality Guideline (SAWQG). ARGs were detected in raw and treated water. In NW-E, the concentrations of ARGs (sul1, intl1, EBC, FOX, ACC and DHA) were higher in treated water than in raw water. Regarding antimicrobial agents, antibiotic and fluconazole concentrations were higher in raw than in treated water. However, in NW-C, trimethoprim concentrations were higher in raw than in treated water. Redundancy analysis showed that bacterial communities were not significantly correlated (Monte Carlo simulations, p-value >0.05) with environmental factors. However, pairwise correlation showed significant differences (p-value <0.05) for Armatimonas, CL500-29 marine group, Clade III, Dickeya and Zymomonas genera with environmental factors. The presence of ARGs and antibiotic residues in the current study indicated that antibiotic resistance is not only a clinical phenomenon but also in environmental settings, particularly in drinking water niches. Consumption of NW-E and NW-C treated water may facilitate the spread of antibiotic resistance among consumers. Thus, regulating and monitoring ARGs and antibiotic residues in drinking water production facilities should be regarded as paramount. [ABSTRACT FROM AUTHOR]

While natural floods play a crucial role in shaping the composition of aquatic communities, the most rivers worldwide are regulated or dammed for anthropogenic purposes, resulting in alterations to the biological and chemical composition of these ecosystems. Studies have demonstrated various negative effects of river regulation on aquatic invertebrate communities globally. However, there is a scarcity of research in Africa, despite its vulnerability to anthropogenic impacts. This study aimed to compare aquatic invertebrate communities in the Phongolo River, an impacted regulated river, and the Usuthu River, a less impacted unregulated river, in South Africa. It further aimed to ascertain whether Lake Nyamithi, a naturally saline lake receiving water from both of the aforementioned systems, exhibited a stronger similarity to one of the two rivers in terms of its aquatic invertebrate composition. Aquatic invertebrate and water samples were collected from 2012 to 2018 over several surveys. The Usuthu River demonstrated a diverse and sensitive aquatic invertebrate community, emphasising its high conservation value. The Phongolo River demonstrated effects of anthropogenic impact, with taxa more resilient to changes in water quality and flow compared to the Usuthu River. Mismanagement and excessive water use may lead to the loss of any remaining sensitive aquatic invertebrate communities in this river. The presence of invasive molluscan in the Phongolo River and Lake Nyamithi also poses a threat to the native aquatic invertebrate communities. These invasive species are currently absent from the Usuthu River although other invasive species, such as the Australian redclaw crayfish, are found in both river systems. Lake Nyamithi displayed a unique aquatic invertebrate community, distinct from both rivers and their floodplains. This study provides important baseline information on the Usuthu River's aquatic invertebrates and emphasises the need to maintain adequate water flow in rivers and floodplains to protect biodiversity and sensitive species. [ABSTRACT FROM AUTHOR]

Mine closure in the Witwatersrand Goldfields of South Africa has resulted in an acid mine drainage (AMD) legacy that is difficult to manage and costly to address. As a short-term measure, three large high-density sludge (HDS) plants were erected that treat 185 megalitres of AMD per day (ML/day), at great cost to taxpayers. Longer-term solutions are sought, as the salt load to the Vaal River System is unacceptable. Long-term modelling was used to assess whether the untreated and HDS-treated AMD could be used for irrigation and to determine the scale of the potential opportunity. The Goldfields waters are not very acidic, and simulations indicate it should be feasible to utilise even the untreated water for irrigation, especially if growers commit to applying limestone to their fields. HDS treatment lowers the corrosivity and trace element concentrations, and because the water is gypsiferous, double cropping will precipitate more than a third of the salts in solution as gypsum in the soil profile, thereby reducing salt load to the water environment. The potential irrigated area depends on the cropping system; it is about 9000 ha for rotational cropping and 30,000 ha for supplemental maize irrigation. It is prudent to seriously consider irrigation as a potential long-term water management option for the Goldfields AMD. [ABSTRACT FROM AUTHOR]

The water quality of the Kaalspruit River, situated in the Gauteng province, South Africa, has been in question over previous years with concerns about the health risks potentially posed by the level of pollution to the surrounding communities. The study aimed to conduct a physico-chemical assessment of water and sediment in the river. In-situ water quality parameters were measured in the field using a multi-parameter water quality meter, while other parameters, such as organic and inorganic constituents were analysed at SANAS accredited laboratories. Water quality results revealed generally poor conditions with minimal seasonal variations, showing low dissolved oxygen and some metal concentrations present in toxic levels. Furthermore, the levels of faecal coliforms and E. coli were beyond the detectable levels in sampling areas of close proximity to informal settlements. Overall, this study revealed that the river system is of poor quality as a result of anthropogenic activities surrounding the Kaalspruit. [ABSTRACT FROM AUTHOR]

Intermittent Water Supply (IWS) is characterised as drinking water distribution systems that are supplied with water for less than 24 hours/day on average. The filling transition from non-supply to pressurised supply is a period of hydraulic instability that negatively impacts water quality, deteriorates infrastructure integrity and intensifies social inequalities. Understanding the factors contributing to the severity of impact from filling is vital to develop effective management strategies. This paper investigates the hydraulic phenomena induced during the short-term IWS filling period and how this behaviour can be exacerbated by elevation and other hydraulic system factors, such as velocity and pressure. Controlled laboratory experiments conducted in the UK and field studies performed in operational networks across South Africa are presented. Results demonstrate the crucial role elevation plays in the network response during the filling transition, emphasising the need for greater consideration of elevation in IWS and well-maintained air relief valves in strategic locations. [ABSTRACT FROM AUTHOR]

The study aimed to assess the impacts on four township areas under Emfuleni Local Municipality of poor water quality from inadequate wastewater management. The failure of the municipality to upgrade and maintain the wastewater treatment facilities has been ongoing for many years and raw sewage spills have been observed on the streets. The objectives of the study were addressed through questionnaires directed at obtaining feedback from household and small business participants. In total, 260 respondents participated, and the results showed differences in the perceptions of impacts due to poor water quality per area of residence; these were significant at 99% confidence interval. Results showed concerns about the impact of wastewater and poor infrastructure on the livelihoods of both residents and business owners. In conclusion, the infrastructural problems resulting in water quality issues have caused severe socio-economic strain on residents and businesses alike. [ABSTRACT FROM AUTHOR]

This study focuses on the evaluation of trace metals as well as microbial contamination of groundwater. Groundwater samples were collected from 17 boreholes. The microbial quality was tested using membrane filtration method. Higher levels of contamination for both E. coli and total coliform was recorded in the wet season. Majority of the boreholes had nitrate levels above the regulatory guideline value of the World health Organisation and the South African National Standards. The water type was established by Piper plot which showed the predominance of a magnesium bicarbonate water type, with alkaline earth metals dominating the alkali metals, as well as the weaker acids (bicarbonates) dominating the stronger ones (Sulphates and chlorides). Most of the trace metals detected were in compliance with the regulatory standard except for aluminium (0.41–0.88 mg/L). The hazard quotient and Hazard indice exceeded 1 mostly for children in both season which implies a possible non-carcinogenic health risk is associated with the continuous consumption of the water resource. The estimations of carcinogenic risk (CRing) for Cr and Pb exceeded the carcinogenic indices of 10−6 and 10−4 which could pose adverse effects on human health for both children and adults. Therefore, it is recommended that measures should be implemented to reduce the risk. [ABSTRACT FROM AUTHOR]

The uMgeni River is one of the most polluted freshwater ecosystems in KwaZulu-Natal. The study aims to assess the response of Clarias gariepinus to water contamination at the Nagle and Inanda dams using selected biomarkers. Samples were collected and preserved as per the analyses to be carried out. Generally, Nagle Dam showed good quality water compared to Inanda Dam. The Inanda Dam population showed a relatively higher prevalence of alterations in the gills and liver than that from Nagle Dam. The degree of alterations showed some variability within each population, however, there was no significant difference (p>0.05) between the two populations. Organ indices of 20 denoting moderate alterations were observed for both populations. Although the mean AChE activity and VtG induction showed no significant difference between the two populations (p>0.05); the lowest AChE activity and the highest VtG level, were observed in the Inanda Dam populations. Both histopathologic and biochemical biomarkers show signs of severely compromised fish health in the Inanda Dam compared to those from Nagle Dam. It is thus, evident that the tributaries feeding the uMgeni River downstream of Nagle Dam are resulting in the increase of pollution level in the Inanda Dam. [ABSTRACT FROM AUTHOR]

A survey of the quality of water flowing from micro-system types to the ocean, along the subtropical east coast of South Africa, showed a wide variation in the concentrations of total nitrogen, phosphorus and phytoplankton biomass in the different systems located, in many cases, only a short distance from each other along the coastline. The origins of the high phytoplankton growth indicate pollutants caused by the land-use in this highly populated coastal region. The main agricultural activities in the area are sugarcane, permanent orchards, and forestry. The levels of N and P in the water varied from ‘good’ to ‘poor’, i.e., TN 0.15–3.99 mg·L−1, TP 0.02–0.33 mg·L−1 and chlorophyll-a from 0 to almost 45 µg·L−1. Rapid coastal population densification appears to have been the cause of the pollution levels measured for total nitrogen, phosphorus, and phytoplankton biomass. Most of the micro-systems with a total modified peri-catchment above 80% were enriched by both TN and TP. While the hypothesis tested was that the main cause was residential development (e.g., septic tank effluent), it was not possible to show any statistical significance to support such a specific conclusion. Although these systems are small individually, the great number along the coastline warrants recognition as important sources of freshwater inflow and nutrients to the marine environment. [ABSTRACT FROM AUTHOR]

With water quality deteriorating rapidly at a global scale, river sections suited to serve as reference sites are being increasingly lost. It thus becomes critical to develop rapid methods to confirm that previously monitored sites continue meet the requirements of reliable reference sites. In the absence of pristine sites, 9 near-natural sites, as defined by the Kleynhans (1996) classification, were used as reference sites for the Luvuvhu River catchment to compare the quality of physico-chemical factors against a biological metric. Baetid mayfly community structure at a site was chosen as an index of water quality, since this family is common in all types of freshwaters, highly diverse and adapted to unpolluted running water. Baetid larvae were sampled monthly from stones-in-current biotopes across 9 sites for over 1 year, between December 2016 and January 2018. A Spearman’s correlation test was used to evaluate the relationship between physicochemical factors and identify redundant variables. Water quality standards were measured against the national water quality guidelines for aquatic ecosystems. We used a generalized linear model to determine the effect of physico-chemical variables on baetid species, and canonical correspondence analysis to show the relationships between baetid species, sites, and physico-chemical variables. A total of 3 039 individuals belonging to 12 mayfly species were recorded. Our findings indicated that while the physico-chemical factors were highly variable, they were within favourable ranges to reflect reference site conditions. While water temperature was the most important driver of baetid community structure in general, as it negatively affected their abundances, a subset of species (Pseudoponnota sp., Pseudocloeon sp., Acanthiops varius and Demoulinia crassi) showed clear responses to changes in TDS and stream width. We conclude that specific baetid species show good potential as biological indicators of reference sites and chronic water temperature stress, making assessment of reference sites easier. [ABSTRACT FROM AUTHOR]

Eutrophication-driven harmful algal blooms (HABs) can have secondary effects on larval fishes that rely on estuaries as nurseries. However, few studies worldwide have quantified these effects despite the global rise in eutrophication. This study presents a novel approach using biochemical body condition analyses to evaluate the impact of HABs on the growth and body condition of the larvae of an estuarine resident fish. Recurrent phytoplankton blooms of Heterosigma akashiwo occur in the warm-temperate Sundays Estuary on the southeast coast of South Africa. The response in body condition and assemblage structure on larval estuarine roundherring (Gilchristella aestuaria) was measured in conjunction with bloom conditions, water quality and zooplanktonic prey and predators. Larvae and early juveniles were sampled during varying intensity levels, duration and frequency of hypereutrophic blooms. This study demonstrated that extensive HABs could significantly impact larval roundherring, G. aestuaria , by decreasing larval nutritional condition and limiting their growth, resulting in poor grow-out into the juvenile phase. Poor condition and growth may likely affect recruitment success to adult populations, and since G. aestuaria is an important forage fish and zooplanktivore, poor recruitment will hold consequences for estuarine food webs. [ABSTRACT FROM AUTHOR]

The overpopulation of urban centres accelerates land use patterns, slum creation and generation of contaminants. As such, this study seeks to investigate the impact of rapid urbanisation on climate variability and surface water quality around Mangaung metropolis. Remote sensing was employed to analyse land use land cover (LULC), normalized differential vegetation index (NDVI) and normalized differential water index (NDWI) changes for a period of 30 years in the Mangaung metropolis. Furthermore, the historical water quality of important rivers and dams were studied in respect of urban contamination. LULC revealed that the urban areas increased exponentially which led to increased loss of vegetation cover and shortage of water availability. The rainfall and water type evolution suggests the influence of urbanisation. This suggests urbanisation accelerates the loss of vegetation cover, thus causing an increase in temperature and reduction in the amount of rainfall, thereby reducing the surface water quantity in the study area. [ABSTRACT FROM AUTHOR]

Freshwater ecosystems are facing degradation from human activities in the form of alterations of flow regimes, changes in land-use, and intensive water abstraction, in turn generating adverse effects on biodiversity and ecological functionality. Efficient assessment of river/stream ecosystem response to such anthropogenic changes is urgently needed. Many human activities that have an effect on water quality and river health are increasing along the Mohlapitsi River, which used to be one of the rivers with good water quality in South Africa. The aim of the study was to assess spatial variation in macroinvertebrate assemblages in relation to water quality of the Mohlapitsi River. A combination of canonical correspondence analysis and univariate analyses were used to examine the macroinvertebrate assemblages at six different sites of the Mohlapitsi River. The spatial difference in macroinvertebrate abundance was mostly related to changes in water quality. The number of taxa and the diversity of macroinvertebrates remained relatively high across the river as compared to other rivers in the Olifants River System. The midstream and downstream sites were mostly dominated by macroinvertebrates tolerant to disturbance/pollution. The most abundant family was the Thiaridae (about 60%) and mainly occurred in the midstream and downstream sites of the river (more disturbed sites). The study showed a higher evenness index in the upstream than the midstream and downstream sites which is an indication of good water quality at the upstream sites of the river. The results suggest that the river is being subjected to a moderate environmental pollution, which requires continuous assessment and monitoring to determine causes and initiate remedial measures. [ABSTRACT FROM AUTHOR]

Ndumo Game Reserve (NGR), a Ramsar site, situated in South Africa's largest floodplain (Phongolo River floodplain) in northern KwaZulu-Natal, with important aquatic ecosystems: the Usuthu and Phongolo rivers and their associated floodplain lakes. While the Phongolo River is regulated, the Usuthu River is unregulated and subjected to fewer anthropogenic activities that influence the downstream environmental quality of this Ramsar system. The present study evaluates the environmental quality of floodplain systems in the NGR. Water and sediment were sampled and analysed from both rivers and associated floodplain lakes during different hydrological periods (flow). Using multivariate statistical techniques, ionic compositions, as well as water and sediment quality indices of the ecosystems were evaluated. Key findings suggest spatial and flow-related differences, which highlight the human-driven impacts from the upper catchments and the rivers influence on their respective floodplain lakes. The environmental quality (water and sediments) could be classified as 'good' and predominantly unimpacted. Notably, ionic composition of river water showed the importance of the unregulated Usuthu River and its contribution to aquatic ecosystems within the NGR and their continued functioning. The quality indices further indicated that metals do not currently pose any ecological risks to these systems. [ABSTRACT FROM AUTHOR]

Saltpans are increasingly being abandoned around the world, leading to the loss of ecosystem services provided by these unique semi-natural wetlands. The desertion of a saltpan at the Swartkops Estuary, South Africa has left behind a large area of desiccated hypersaline sediment and a sharp decrease in waterbird abundance and diversity. Here, we explore the potential for restoring this saltpan's wetland function using stormwater inflow to support multiple ecosystem services and improve estuary health. Stormwater will be able to flow into the saltpan as a passive restoration approach that can maintain the site as a wetland habitat. This will contribute to improving the health of a nationally important, yet highly degraded, estuary by retaining 758 ML of stormwater to achieve full capacity, containing an estimated 2908 kg of dissolved inorganic nitrogen and 68 kg of dissolved inorganic nitrogen. Additional ecosystem services such as biodiversity maintenance, carbon storage and societal values can be expected. However, this would create a novel hypersaline stormwater wetland and a strategic adaptive management approach will be required. Management must be guided by monitoring, which should comprise collection of basic environmental data to establish a baseline condition, and against which, long term changes and responses resulting from stochastic events can be assessed and mitigated through the use of achievable ecological restoration targets. [ABSTRACT FROM AUTHOR]

Interest in greywater reuse is increasing in South Africa, because of the potential to supplement scarce freshwater resources in the face of increasing demand and aridity. This paper aims to inform the water saving-risk trade-off associated with residential untreated greywater use, through a statistical analysis of greywater quality results as sourced from prior South African studies. Greywater sources included in this review were the bathroom, kitchen, laundry, mixed and general residential sources. Variability in terms of each of the reported physical, chemical and microbiological constituents by source and between result sets was noted. Statistically significant differences were evident between the pH, conductivity and phosphorus values of certain sources. A risk assessment undertaken for each of the constituents revealed further variability. The constituent with the highest number of high-risk samples was total dissolved solids. The relatively high risk and negative consequences in greywater practices in terms of public health, the environment, and infrastructure, given this variability, provide insight into the trade-off with potential water savings. It is recommended that a more nuanced view of the potential potable savings associated with greywater reuse and also improved risk management is required by the user. [ABSTRACT FROM AUTHOR]

Historical data (July 1998 - June 2018) for the middle Olifants River, Limpopo River system, were compiled to evaluate the dynamics of selected water physico-chemical parameters with river discharge. The concentration of most water quality parameters increased over time. However, these concentrations are rapidly decreased, or reset, by the rapid filling, or spilling, of Loskop and/or Flag Boshielo Dams during a high-flow event. The flow-duration curves for stations below impoundments in the middle catchment on the Olifants River are typical of highly regulated rivers, although releases from Flag Boshielo Dam were more consistent through the 20 years. No outflow from Loskop Dam was recorded for 5.4% of the 20 years. The load-duration curves for gauging weirs on the Olifants and Elands rivers immediately upstream of Flag Boshielo Dam showed that the 'tolerable' concentrations were exceeded for total dissolved solids at the 60th and 20th percentiles of the flow, respectively. In addition, records for electrical conductivity, sodium, chloride, and alkalinity frequently exceeded the 'tolerable' concentrations at these sites. The results for Loskop and Flag Boshielo dams are generally lower than the tolerable concentrations for the parameters evaluated. Management of the flow regulation of the Olifants River should be aimed at meeting the water quality stipulations for all users in the agricultural, domestic, industrial, and recreational sectors. [ABSTRACT FROM AUTHOR]

The continuous monitoring of soil health and irrigation water quality influences the crop yield and the quality of agricultural produce. In this study, various physicochemical parameters were measured to monitor the soil profile, irrigation water and maize quality harvested from the Buhle farm located in Howick in the KwaZulu-Natal Province of South Africa to ensure steady high quality food supply for the consumer. The maize crop was sampled from the maize stalk, the corresponding soil samples were collected from the upper surface of the soil (0-15 cm surface layer) using the soil auger and the irrigation water sample was taken from the irrigation tanks using polyethylene sample bottles. The physicochemical parameters considered for irrigation water were pH, electrical conductivity, alkalinity and chloride due to their ability to affect water quality which consequently affect crop growth and quality. The soil physicochemical parameters considered were moisture content, pH, electrical conductivity, texture, total nitrogen and nutrients (protein, fat, fibre, starch, total mineral matter and elements). These parameters determine the soil quality, water content, the ratio of absorbed and lost energy, concentration of ions and elements present which in turn affect or promote the yield and quality of crops. Maize was analysed for nutritional content and medicinal health-promoting compounds to assess the influence of soil and irrigation water on the maize quality and consequently the health of the consumers. The concentrations of total nitrogen (N), phosphorus (P) and potassium (K) in soil, which were translated into high soil fertility were 2700, 19 and 222 mg kg-1, respectively. The results obtained were within the required specification for high quality maize production. The levels of sodium, sodium adsorption ratio and electrical conductivity in the irrigation water were 0.05 mg L-1, 2 and 1.81 µS m-1, respectively, indicating safe water of low salinity. Maize was high in starch (58.6%) while fibre, protein and fat contents in the maize were 23.4, 9.01 and 4.55%, respectively, indicating suitability for consumption. Furthermore, the total anthocyanin, total flavonoids and total phenolic acid content of the maize were 8.5, 49.5 and 100 mg L-1, respectively. Overall, this study showed the presence of health-promoting compounds in the maize crop which is associated with its high quality for consumption. The validity of the analysis methods was tested using certified reference materials. The concentrations of the reference materials were not statistically different from the certified values, attesting to the validity of the analysis methods. [ABSTRACT FROM AUTHOR]

It is difficult to predict and manage the ecological consequences of multiple water quality stressors on our freshwater systems. This is due to the dynamism of the source-stressor-response relationships and multiple factors including lack of data, complex impact pathways and risks, and uncertainties that are difficult to parameterise. We present a risk-based probability modelling approach using a Bayesian network (BN), to manage multiple water quality stressors at multiple spatial scales. We illustrate the use of this approach, by evaluating the probable ecological effects of altered water quality associated with multiple sources in three case study rivers in South Africa. Water quality and land use activity were used to describe conceptual risk pathways, parameterise the BNs and model the probable consequences of multiple water quality stressors. The BN model demonstrated that the endpoints that were selected for the study reflected the risks associated with the levels of the input water quality variables. The model further demonstrated that the electrical conductivity BN was just as sensitive as the more complex salt model. The BN model was further able to accurately represent risks to all systems irrespective the water quality data base size. This approach can contribute towards more sustainable water resource management. [ABSTRACT FROM AUTHOR]

• Mallomonas corymbosa, M. kenyana and M. porte-ferreae were found in the Vaal River, South Africa. • Cell morphology and geographical distribution of each species are presented. • Water quality of the Vaal river at the time of sampling is presented. • The finding of M. corymbosa represents the first record of this species in Africa. • M. kenyana, a tropical/subtropical species, were found in temperate regions in South Africa. This paper reports on the presence of three Mallomonas species (Phylum Ochrophyta) in the Vaal River, South Africa. Scanning electron microscope observations of entire cells with intact scales and bristles allowed accurate identifications of M. corymbosa, M. kenyana and M. portae-ferreae. Descriptions and dimensions of each of the three species are given, their geographical distribution is discussed and physico-chemistry of the water at the time of their finding is presented. M. corymbosa was recorded for the first time in Africa, expanding its known geographical distribution to an additional continent. The climatic preferences of the tropical and subtropical species, M. kenyana were extended to temperate regions in South Africa. These species were present under eutrophic to hypertrophic conditions, a water temperature of 25.4 °C, neutral to slightly alkaline water (pH 7.25) and a conductivity value of 440 µS/cm. [ABSTRACT FROM AUTHOR]

The Hartbeespoort Dam is a discharge point of a catchment that is characterized by urbanization, mining, industrial, and agricultural activities. These activities coupled with fluxes of heavily polluted wastewater from informal settlements, wastewater treatment works, as well as runoff from golf courses have led to the development of recurring harmful algal blooms (HABs). The predominant cyanobacteria scum that is largely covering the Dam water is toxic to fish and poses serious public health risks. Phosphorus is the limiting nutrient in terrestrial aquatic systems and excess concentration in the waters usually results in eutrophication. The productivity level in Hartbeespoort Dam is also a function of total phosphorous (TP) level, showing a positive correlation with chlorophyll-a, an index for phytoplankton which are predominantly HABs in this Dam. Analysis of long-term in situ water quality data (1980–2020) show that TP is not the only driver, changes in surface water temperatures also affect the productivity level, especially, when TP levels are below a threshold of approximately 0.4 mg/L. Chlorophyll-a was retrieved from current generation high resolution satellite (Landsat and Sentinel) at 5-year interval. Standard band ratio-based ocean color model applied to satellite data produced an accuracy of R2 = 0.86 and RMSE of 5.56 µg/L. Time series analysis of in situ and satellite data show similar trends including capturing the effect of biocontrol on productivity levels between the late 1980s and the early 1990s, after which productivity increased with an increased flux of TP. Since 2015, the average annual surface temperature in the Dam has decreased leading to the decline in productivity level despite increasing levels of TP. The spatial dynamics of the HABs is a function of the discharges levels of the various rivers draining into the Dam as well as its geometry. Relatively higher concentrations are observed near river discharges and in areas of restricted water circulation. [ABSTRACT FROM AUTHOR]

South Africa is facing a crisis in providing adequate clean water in its respective rural areas, townships and informal settlements. In this study, we explored the citizens' perceptions of water insecurity in South African rural areas, and the effects of water conflict on agricultural practices and livelihoods. The study adopted a quantitative study and utilised a systematic simple random sampling in selecting 90 respondents who provided data through a questionnaire survey. Data analysis was carried out using Statistical Package for Social Sciences (SPSS) version 22. Findings revealed that water insecurity manifests through poor quality water, absence of provision of water by rural municipalities, and reliance on unsafe water sources such as dams and rivers. Limited production for smallscale business farmers, a rise in poverty and high hunger incidents were considered the major impacts of water scarcity. The study concludes that rural households in the Eastern Cape Province are water insecure, which negatively affects livelihoods and agricultural practices. The study recommends investment in water harvesting infrastructure, tapping of underground water through borehole drilling and investment in irrigation infrastructure as measures to deal with water insecurity in rural communities. [ABSTRACT FROM AUTHOR]

The impact of treated municipal wastewater (TMW) irrigation on soil and grapevines was assessed under field conditions in vineyards in the Coastal region of South Africa. Grapevines were irrigated using TMW from the City of Cape Town uninterruptedly over a period of 11 years. Grapevines were either rain fed, irrigated with TMW via a single dripper line, or received twice the volume via double dripper lines. The quality of the TMW used for vineyard irrigation was acceptable, and below the minimum criteria stipulated by the General Authorisations to irrigate up to 500 m³ per day in terms of pH, ECw and SAR. Mean Na+ concentration in the TMW exceeded the critical value of 100 mg/ℓ for irrigating grapevines in South Africa. The Cl- levels in the TMW were well below the threshold value of 700 mg/ℓ at which toxicity in grapevines might occur. Consistently high P concentrations measured in the TMW could lead to the formation of algal blooms in water storage facilities and bio-fouling of irrigation equipment. The low N content in the TMW could not supply the annual N requirement of grapevines. The annual amount of P applied via the single dripper lines was slightly below grapevine requirements, whereas double the TMW irrigation applied excessive amounts of P. Amounts of K+ applied via TMW irrigation was in excess of annual grapevine requirements, which could affect wine quality negatively. The amount of Ca2+ and Mg2+ applied via the TMW also exceeded annual grapevine requirements. [ABSTRACT FROM AUTHOR]

Environmental water requirements (EWRs) are set for South Africa's estuaries to ensure that they are maintained in a state that is both achievable and commensurate with their level of conservation and economic importance. However, these EWRs are typically determined on the basis of models and scenario analyses that require extrapolation beyond existing data and experience, especially if climate change is considered. In the case of the Berg Estuary, South Africa, available data on changes in freshwater flow and water quality span a period of at least five decades (1970s--present) during which significant reduction in flows has been observed. Monitoring data also cover an extreme 3-year drought, from 2015-2017, which provided a unique opportunity to study the effects of severe freshwater starvation (zero-flow for an extended period) on this large, permanently open system. Our analyses show that mean annual runoff (MAR) under present-day conditions has been reduced to around 50% of that under reference (natural) conditions and that reduction in runoff during the low-flow season (summer) has been more severe (80-86% reduction) than for the high-flow season (39-42% reduction). The salinity gradient now extends much further upstream than under reference conditions. Hypersaline conditions along with a reverse salinity gradient were recorded in the estuary for the first time ever during the drought of 2015/17. Levels of dissolved inorganic nitrogen (NOx) reaching the estuary from the catchment have increased dramatically (6-7 fold) over the past five decades, dissolved reactive phosphate (PO4) slightly less so (2-3 fold), but ammonia (NH4) hardly at all. Increases in nutrient input from the catchment in the high-flow season are also much more dramatic than in the low-flow season. The estuary is no longer compliant with gazetted EWRs and requires urgent interventions to restore the quantity and quality of freshwater it receives. [ABSTRACT FROM AUTHOR]

Excessive discharge of poorly treated effluent has impacted global water resource systems intensely. The declining state of wastewater treatment plants (WWTPs) is a significant source of pollution in water resources. There is evidence of water resource quality deterioration in natural environments caused by effluent discharges. We assessed the impact of wastewater treatment effluent on the quality of the Crocodile River. For spatial distribution, we collected data from three WWTPs discharging effluent into the Crocodile River and from three points situated downstream of each WWTP. Physicochemical and microbiological parameters such as pH, electrical conductivity, chemical oxygen demand, phosphates, nitrates, ammonia, and Escherichia coli were analysed using standard methods of the American Public Health Association. The water quality index was also calculated to give an overall indication of pollution within the catchment. The results show that WWTPs were not complying with the effluent standards set out in their water use licence. The WWTP effluent had a negative impact on downstream water quality, with the water quality index indicating low quality of discharged effluent. It is recommended that a regular and consistent water resource quality monitoring programme be implemented, particularly in areas where effluent discharges are prevalent. In many African nations, water pollution is a serious problem that may be traced to a variety of sources. Surface water pollution has adverse effects on aquatic ecosystems and reduces the availability of clean water. In most semi-arid to dry southern African regions (e.g. South Africa), water scarcity is a significant concern. In these regions, water is a vital resource that must be protected at all times, given that the inadequate infrastructure of wastewater treatment facilities adds to the decline in South Africa's water quality standards. [ABSTRACT FROM AUTHOR]

Water renewal and flushing in small, intermittently open or closed estuaries is receiving increasing attention particularly in light of the climate change induced alterations in run-off, wave and sediment transport conditions along coasts. The challenges of predicting the stratification-circulation state and the balance between tidal or freshwater flushing in response to the mouth dynamics of small, wave-dominated estuaries is the focus of the paper. Such predictions are required for determining estuary freshwater requirements or establishing an estuary's capacity to maintain sound water quality under pollutant discharges. Advances in simulating changes in stratification-circulation over long time scales are limited. Instead attention has focused on generating indices of stratification or water quality state using heuristic methods. In this paper, systems dynamics modelling is applied to simulate the non-linear response of the estuary to changes in river and marine water fluxes. The estuary is modelled as a basin with a specified water volume to water level relationship, connected to the sea by a channel with variable sill height, but fixed width. The direction and magnitude of the flow through the mouth determines whether the sill height erodes or accretes and hence the mouth dynamics (see Slinger, 2017). The tidal flux through the mouth co-determines the volumetric exchange of salt, influencing both the stratification state of the estuary and the degree of tidal or freshwater flushing. This is also influenced by run-off. The resulting dynamic balance is captured in two bulk indices, the Estuarine Richardson number and the bulk densimetric Froude number. Using measured data from the Great Brak Estuary, South Africa, the model is calibrated. Model simulations demonstrate the importance of tidal flushing and concomitant mouth breaching for water renewal as freshwater flushing declines under scenarios of increased water abstraction. Although the estuary remains partially mixed, there is increased average salinity and a more uniform the water column. Water releases and mouth breaching bring about a more natural stratification-circulation state, but these effects are short-lived. • Parametric simulation of water renewal in wave-dominated, intermittent estuaries. • A stratification index analogous to the Estuarine Richardson number is modelled. • A circulation index analogous to the bulk densimetric Froude number is simulated. • Stratification-circulation simulations indicate increased water column uniformity. • Mouth breaching & floods temporarily allow more natural stratification-circulation. [ABSTRACT FROM AUTHOR]

• Sediment and P accumulation rates were higher in clastic wetlands. • Organic matter content and associated Fe and Al complexing agents control P distribution patterns. • System-scale characteristics influence catchment hotspots for sediment and phosphorus retention. Anthropogenic-induced acceleration of sediment and associated nutrients presents a serious challenge to water resource management across the globe. While wetlands are potential natural solutions, little is known of how well key wetland types attenuate downstream sediment fluxes and how these relate to local- and catchment-scale factors. This research aimed to develop an understanding of patterns and rates of sediment and phosphorus retention in valley-bottom wetlands in South Africa. The geomorphology, sedimentology and historical accretion rates of three wetlands which offered diversity in size, catchment position and degree of organic accumulation were compared to ascertain the impact of local- and catchment-scale factors. Estimates of sediment and associated phosphorus accumulation suggest higher rates in clastic sediment-dominated wetlands (1089–7655 g sediment m−2 yr−1, 0.4–1.6 g-P m−2 yr−1) compared to an organic sediment-dominated system (601–1308 g-sediment m−2 yr−1, 0.2–0.3 g-P m−2 yr−1). Sediment accretion rates generally increased longitudinally, indicating that distal wetland reaches act as sediment and phosphorus retention hotspots. Phosphorus distribution patterns were primarily attributed to variations in organic matter content and associated aluminium and iron complexing agents in fine-grained sediment deposits, while particle size distributions were less important. However, the relevance of individual complexing agents in phosphorus dynamics varied among wetlands with differing landscape conditions. Contrasts between these systems reflect variations in catchment lithology and hydroclimatic regime, which influence the relative magnitude of sediment supply and vegetation productivity. We postulate that intermediate-sized wetlands characterised by catchments around 900 ha in size, gentle longitudinal slopes (∼2 %), a high proportion of fine sediment deposition, limited organic matter breakdown, and a long vegetation growing season provide optimal conditions for sediment and phosphorus accumulation. This system-scale information is essential to guide management decisions to identify and prioritize within-catchment 'hotspots' of sediment and phosphorus retention. [ABSTRACT FROM AUTHOR]

Environmental water requirements (EWRs) are set for South Africa’s estuaries to ensure that they are maintained in a state that is both achievable and commensurate with their level of conservation and economic importance. However, these EWRs are typically determined on the basis of models and scenario analyses that require extrapolation beyond existing data and experience, especially if climate change is considered. In the case of the Berg Estuary, South Africa, available data on changes in freshwater flow and water quality span a period of at least five decades (1970s–present) during which significant reduction in flows has been observed. Monitoring data also cover an extreme 3-year drought, from 2015−2017, which provided a unique opportunity to study the effects of severe freshwater starvation (zero-flow for an extended period) on this large, permanently open system. Our analyses show that mean annual runoff (MAR) under present-day conditions has been reduced to around 50% of that under reference (natural) conditions and that reduction in runoff during the low-flow season (summer) has been more severe (80–86% reduction) than for the high-flow season (39–42% reduction). The salinity gradient now extends much further upstream than under reference conditions. Hypersaline conditions along with a reverse salinity gradient were recorded in the estuary for the first time ever during the drought of 2015/17. Levels of dissolved inorganic nitrogen (NOx) reaching the estuary from the catchment have increased dramatically (6–7 fold) over the past five decades, dissolved reactive phosphate (PO4) slightly less so (2–3 fold), but ammonia (NH4) hardly at all. Increases in nutrient input from the catchment in the high-flow season are also much more dramatic than in the low-flow season. The estuary is no longer compliant with gazetted EWRs and requires urgent interventions to restore the quantity and quality of freshwater it receives. [ABSTRACT FROM AUTHOR]

The degradation of freshwater ecosystems can be attributed to stressors associated with the increased demand for water and other aquatic resources. Freshwater ecosystems face such challenges in supporting agriculture, industry, and high-density urban areas in KwaZulu-Natal (KZN) province, South Africa. In this study, the presence of fish species and their abundance was quantified at 40 sites in KZN on 16 major rivers systems. Surveys were done during a drought period between February 2015 and April 2016, as part of the River Health Programme, a national river monitoring assessment. The Fish Response Assessment Index (FRAI) was used to evaluate the condition of the sites, and redundancy analysis was used to evaluate the habitat, water quality and fish community relationships. The FRAI scores showed four sites to be in a 'Seriously Modified' condition. These areas were associated with intensive agricultural activities and urban environments. The presence of invasive fish species, abstraction and industrial use all had negative impacts on the ecological state of the rivers. When compounded by excessive water use, the drought resulted in poor fish community integrity, highlighting the vulnerability of fish communities in this region. The absence or low abundances of some indigenous fish alongside the high presence of invasive fish requires additional investigation. Results highlight the importance of mitigation measures against anthropogenic impacts should be enforced to ensure sustainable use of KZN water resources. [ABSTRACT FROM AUTHOR]

Extinction risk for 101 valid species and 18 unique genetic lineages of native freshwater fishes of South Africa was assessed in 2016 following the IUCN Red List criteria. An additional five species (three new species that were described and two species that were revalidated subsequent to the 2016 assessments) were assessed in the present study. A synthesis of the outcome of the assessments of the 106 valid species and 18 genetic lineages indicates that 45 (36%) of South Africa's freshwater fish taxa are threatened (7 Critically Endangered, 25 Endangered, 13 Vulnerable). Of the remaining taxa, 17 (14%) are listed as Near Threatened, 57 (46%) are Least Concern and five (4%) are Data Deficient. More than 60% of the endemic taxa are threatened. The Cape Fold Ecoregion has the highest proportion of threatened taxa (67%) due to the existence of a unique assemblage of narrow‐range endemic species. Galaxias and Pseudobarbus have the highest number of highly threatened taxa as most of the species and lineages in these genera are classified as either CR or EN. Major threats to the native freshwater fishes of the country are invasive fish species, deterioration of water quality, impoundments and excessive water abstraction, land use changes and modification of riverine habitats. Immediate conservation efforts should focus on securing remnant populations of highly threatened taxa and preventing deterioration in threat status, because recovery is rare. Accurate delimitation of species boundaries, mapping their distribution ranges, improved knowledge of pressures and long‐term monitoring of population trends need to be prioritised to generate credible data for the 2026 IUCN threat status assessments and designation of important fish areas as part of the National Freshwater Ecosystem Priority Areas (NFEPA) initiative. [ABSTRACT FROM AUTHOR]

South African rivers generally receive waste from inadequate wastewater infrastructure, mines, and farming activities, among others. The uMsunduzi River in KwaZulu-Natal, South Africa, is among these recipients with recorded poor to very poor water quality. To identify parts of the uMsunduzi River that are polluted by Cryptosporidium and Escherichia coli (E. coli), this study mapped out pollutants emanating from point and non-point sources using the Soil and Water Assessment Tool (SWAT). Streamflow calibration in the upper and lower reaches of the catchment showed good performance with R² of 0.64 and 0.58, respectively. SWAT water quality output data were combined with a Quantitative Microbial Risk Assessment (QMRA) to understand the microbial health implications for people using river water for drinking, recreational swimming, and non-competitive canoeing. QMRA results for Cryptosporidium and pathogenic E. coli showed that the probability of infection for most users exceeds the acceptable level for drinking and recreation as outlined in the South African water quality guidelines, and by the World Health Organization (WHO). The results of this study can be used as a baseline to assess the economic and health implications of different management plans, resulting in better-informed, cost-effective, and impactful decision-making. [ABSTRACT FROM AUTHOR]

The mining and mineral processing of Cu-Ni-PGM sulfide ores in South Africa occurs in semi-arid regions. The scarcity of water resources in these regions has become one of the biggest challenges faced by mineral concentrators. As a result, concentrators are forced to find ways through which they can manage and control their water usage. The recycling and re-use of process water in mineral concentration plants has therefore become a common practice. This practice is beneficial in that it reduces reliance on municipal water and harnesses compliance to stringent environmental regulations on freshwater usage. This approach also offers a better response to the Sustainable Development Goals (SDGs) for the mining industry, as water and its preservation form part of the SDGs. This practice could, however, be somewhat concerning to a process operator because recirculated water often has higher concentrations of ions compared to fresh or potable water. This is because an unintended change in the process water quality may affect critical aspects of flotation such as the stability of the froth. This issue has led to the need for both the mining industry and researchers in the field to find the ions in process water that have the greatest impact on froth stability. Thus, the authors of this study investigated the effects of various ions common in the process water of a typical Cu-Ni-PGM ore on froth stability using a 3 L bench scale flotation cell. Solids and water recoveries were used as proxies for froth stability. These were further complemented by bubble size, water recoveries, foam height, and dynamic foam stability from two-phase flotation systems. A two-phase foam study resulted in observations that supported findings from a three-phase study. Generally, single salt solutions containing Ca2+ and Mg2+ ions resulted in higher water recoveries both in the two-phase foam and three-phase froth studies, increases in foam heights and dynamic foam stability, and a decrease in bubble size compared to the solutions that contained Na+. SO42− also resulted in increased foam stability compared to Cl− and NO3−. These results showed that the divalent inorganic electrolytes—Ca2+, Mg2+, and SO42−—were more froth- and foam-stabilizing than the monovalent inorganic electrolytes—Cl−, NO3−, and Na+. This finding was in agreement with previous research. The findings of this study are deemed crucial in the development of a process water management protocol in sulfidic Cu-Ni-PGM ore concentrators. However, more comparative three-phase froth stability tests are needed as subjects of future investigative work to further ascertain specific ion effects on froth stability in sulfide ores. [ABSTRACT FROM AUTHOR]

The Oceans and Coastal Information Management System (OCIMS) was launched by the South African Government in 2015 to support the development and governance of the South African ocean economy. The OCIMS has established knowledge tools for marine spatial planning, maritime domain awareness, search and rescue, water quality and harmful algal bloom monitoring. Those tools are used daily by stakeholders across government departments, industry, and civil society. Unlike many other operational oceanographic and coastal systems around the world, the OCIMS was designed from its inception using inputs from stakeholders. Continuous engagements between developers and stakeholders have ensured that the system remains fit for purpose. The OCIMS is both locally relevant and globally cognizant. Developments are undertaken to ensure inter-operability with other systems in the world and promote the exchange and discovery of data. The OCIMS project was able to leverage co-funding and the sharing of data and expertise through partnerships across the public and private sectors. These partnerships have been essential to the success of OCIMS and would not have been possible without continued engagements and the sustained funding provided by the South African national government. The development pathway followed to establish the OCIMS could benefit other countries looking to implement their own operational ocean and coastal system knowledge platform. • The Ocean Information Management System supports Blue growth. • The formalization of stakeholder's engagement ensures co-design and relevance. • Adherence to international best practices promotes global visibility. • Co-funding from partners help leverage cost and human capacity. • Secure funding streams from government are essential to ensure sustainability. [ABSTRACT FROM AUTHOR]

Benthic macroinvertebrates play a vital role in ecosystem functioning, such as nutrient cycling, primary production, decomposition and material translocation. A study was done to determine the functional feeding groups (FFGs) distribution along two streams of the Olifants River System, South Africa. There were longitudinal differences of the functional groups but were more pronounced in the Dwars River than in the Spekboom River. Collector-gatherers and collector-filterers were the most abundant groups recorded in both rivers. The least abundant groups were the shredders and scrapers in both rivers. The highest abundance of shredders in both rivers was at upstream sites (DS1 and SS1), more scrapers were found at midstream sites (DS3 and SS2), collector-gatherers and collector-filterers increased in the downstream (SS4) of the Spekboom River and predators were nearly constant in relative abundance at all sites. The relative abundance and richness of the FFGs did not conform completely to the river continuum concept (RCC). This could be related to the degradation of the catchment resulting from human activities which affected the quality of the water. [ABSTRACT FROM AUTHOR]

We study the distributional impacts of a water pollution tax in the Olifants river basin using a regional environmental computable general equilibrium (CGE) model. The distributional impacts were evaluated considering both the household income and spending-side effects. We find that the water pollution tax is progressive on the income side as the poorest and vulnerable derive lower shares of their income from capital, which bears the biggest burden of the tax. However, the tax is regressive on the expenditure side due to the higher share of pollution-intensive goods in poor households' expenditure. The net effect of the tax is, however, not pro-poor. Revenue recycling through a subsidy to pollution abatement sectors mitigates the adverse distributional impacts of the tax whereas uniform direct lump-sum transfers to households' income reverse the adverse distributional impacts. [ABSTRACT FROM AUTHOR]

The study assessed the impact of water and sediment quality on benthic macroinvertebrate assemblages in the Dwars River, a tributary of the Olifants River, Limpopo province, South Africa. Physico-chemical variables, heavy metals and macroinvertebrates were collected using standard methods. A multivariate analysis, Canonical Correspondence Analysis (CCA), was used to examine the macroinvertebrate community structure. Based on the selected physico-chemical variables and metal concentrations assessed, the water quality and sediment quality are deteriorating mainly in the downstream areas. The number of taxa and the Average Score per Taxon (ASPT) were significantly different between sites and seasons, with more taxa recorded in the upstream section of the river and in winter. A higher proportion of sensitive and high-scoring taxa (Ephemeroptera, Plecoptera and Trichoptera) were recorded in upstream and midstream sites and in winter. The CCA analysis showed an association of heavy metal concentration in the sediment with the distribution of macroinvertebrate taxa tolerant to poor water quality in the downstream section of the river. Because of the potential impacts of rapid economic development in the catchment, regular monitoring of the river is recommended, to detect potential river health problems early. [ABSTRACT FROM AUTHOR]

The Ga-Selati River is subjected to different forms of pollution from mining, industrial and agricultural activities, and human settlements. The objectives of the study were to assess heavy metal pollution and to determine possible sources of pollutants in the river. Water and sediment samples were collected and analysed for the following selected metals: arsenic (As), chromium (Cr), iron (Fe), manganese (Mn), nickel (Ni) and zinc (Zn) using sequential Inductively Coupled Plasma-optical emission spectrometry (ICP-OES). The enrichment factor (EF) and geo-accumulation index (Igeo) were used to determine the level of metal pollution in the sediment. The results indicated that Cr and Ni were the most accumulated elements in the sediments, and the midstream sites (S4 and S5) showed a much higher pollution level than the upstream and downstream sites. The main sources of pollutants were mining, wastewater/sewage and agricultural discharges. This may pose a serious threat to the river and health risk to the nearby rural communities, which rely on the river, especially for drinking water. Proper management strategies to reduce pollution is therefore necessary. [ABSTRACT FROM AUTHOR]

Despite the rapid extension of public service delivery since the end of Apartheid, many rural citizens in South Africa still rely on their own initiatives and infrastructure to access water. They construct, improve, operate and maintain infrastructure of different complexities, from individual wells to complex collectively owned water schemes. While most of these schemes operate without legal recognition, they provide essential services to many households. In this article we will first provide an overview of the growing international body of literature describing self-supply as an alternative pathway for public service delivery. We then take a historical perspective on the role of communities and self-supply in South Africa and describe the emergence of six collectively owned, gravity-fed, piped schemes in Tshakhuma, Limpopo Province. We describe and compare these systems using key characteristics like resource access, investment, construction, operation, maintenance and institutional governance. We further assess their performance with regard to coverage, service level, reliability, governance structure, accountability and water quality. We do so because we are convinced that lessons learned from studying such schemes as locally adapted prototypes have the potential to improve public approaches to service delivery. The described cases show the willingness of community members to engage with service delivery and their ability to provide services in cases where the state has failed. The assessment also highlights problematic aspects of self-supply related to a lack of accountability, technical expertise and the exclusion of disadvantaged community members. By describing and assessing the performance of rural self-supply schemes, we aim to recognize, study and learn from such schemes. We consequently do not conclude this article by providing answers, but by raising some pertinent, policy-relevant questions. [ABSTRACT FROM AUTHOR]

Organochlorine pesticides (OCPs) and phthalates are amongst the most emphasized man-made environmental contaminants, due to their prevalence, persistence and potential to induce adverse effects in organisms. In addition to prevailing industrial and domestic activities, their presence in the environment is exacerbated by leaching from associated materials, run-off and emissions. The Loskop Dam in the Mpumalanga Province, South Africa, is located on the Olifants River, which flows through a hub of industrial and agricultural activities. Research aimed at monitoring the levels of OCPs and phthalate contamination in South Africa, particularly in the Olifants catchment, has been limited and is restricted to short-term monitoring. In this study, the spatial and temporal variations of 21 OCPs and 7 phthalates in water and sediments from Loskop Dam were evaluated over a 3-year period (2015-2017). Annual average OCP levels ranged from 0.013±0.006 to 0.36±0.13 µg/L in water and from below the limit of detection to 2.4±1.2 µg/kg in sediments. Phthalates were present at average concentrations ranging from 0.023±0.041 to 2.1±1.5 µg/L and 20±0.63 to 55±6.9 µg/kg in water and sediments, respectively. The levels of OCPs and phthalates were greatest in autumn, attributed to higher input sources and concentration effects due to lower water levels. Phthalates were present at greater quantities at the inlet, while OCP accumulation was observed at the upper reaches of the dam. This may be an indication of the differences in input sources and translocation of these compounds, related to the topography of the dam and variability in water flow rates. These findings are important in highlighting the environmental and health concerns that may arise in the Olifants catchment area. After considering the outcomes of this study, we propose the implementation of regular and stringent monitoring strategies, which include surveys of OCPs and phthalates for Loskop Dam and similar water systems globally. [ABSTRACT FROM AUTHOR]

Increasing awareness of deteriorating health of aquatic ecosystems, as a result of human activities, has led to the suggestion that fish host-parasite relationships are possible bioindicators of environmental pollution. This study examined the impact of water quality and trace elements on the seasonal occurrence of Cichlidogyrus philander Douëllou, 1993. In situ water quality variables were recorded, and sediment and water samples collected, for analysis of trace elements and metals. Collections were performed monthly from February 2016 to January 2017, during which 164 Pseudocrenilabrus philander (Weber, 1897) hosts were collected and their C. philander loads were counted. Monogeneans occurred throughout the year, with prevalence, mean intensity and abundance reaching maximum values of 90.74%, 29.9 and 29.4, respectively, in summer. Trace element and metal levels were highest in sediment and lowest in water. No significant correlation was found between water quality and trace elements on infection variables. Trace elements did not have an effect on the occurrence of the parasite, therefore it was concluded that the changes observed during the study were not brought on by changes in water quality as a result of pollution, but rather that these changes relate to seasonal variation in infection biology of C. philander. [ABSTRACT FROM AUTHOR]

Background: The understanding of the impact of land-use on the dynamics of phytoplankton assemblages during varying climate conditions on rivers is limited. Objective: To determine the impact of land-use types and flow on phytoplankton assemblages in the Sabie River. Methods: The relationships between land-use patterns, water quality and phytoplankton assemblages were analysed using canonical correspondence analyses (CCA). Results: Six main land-use types could be distinguished in the eight identified sub-catchments of the river. The CCA results showed that the land-use had a stronger correlation with phytoplankton classes during the higher flow conditions than during low flow conditions. The forestry land-use type had the strongest correlation with nitrate-nitrite concentrations in the Sabie River. Chlorophyll-a concentrations were higher during 2016, and a slightly lower number of genera were observed for the class Chlorophyceae. During 2017 the number of genera of the class Cyanophyceae decreased together with chlorophyll-a and total cell concentrations. Conclusion: Low flow conditions favoured filamentous genera that are common to mesotrophic conditions while higher flow conditions favoured single-celled small genera more common to oligotrophic waters with higher disturbance. This study showed that flow has the potential to enhance the impact of land-use on phytoplankton community dynamics in a river system and thereby may have further impacts on the health and activities of surrounding communities. [ABSTRACT FROM AUTHOR]

Background: Although the Kruger National Park (KNP) is a protected area, it is not exempted from anthropogenically induced impacts, which often compromise river water flow and quality. Measures of river water quality in South Africa have conventionally been based on water chemistry as well as different ecological indicator groups such as fish and macroinvertebrates. Diatoms have been shown to be useful indicators of changes in water quality resulting from pollution and land-use impacts. Objectives: To determine the applicability of diatoms for hind-casting water quality in the KNP and to compare recent diatom community composition with those from the 1980s. Methods: In this study, pH and electrical conductivity (EC) were used to evaluate temporal changes in water quality of three rivers within the KNP. Additionally, we made use of historic diatom samples from three of the five perennial rivers to evaluate if diatom communities reflected changes in water conditions between 1983 and 2015. Results: Diatom community structure was significantly different between 1983 and 2015. Diatom-based index scores (SPI) indicated an improvement in water quality for the Letaba and Olifants rivers. Conclusion: Diatoms were shown to be useful indicators of current water quality and are also useful for determining temporal changes. [ABSTRACT FROM AUTHOR]

Background: Effluents from agricultural activities, metal and peat mining, urban and industrial areas, informal settlements and wastewater treatment plants all influence tributaries feeding the Mooi River. All these land uses ultimately result in a deterioration of water quality in the Mooi River. Objectives: The main objective was to relate the effects of inflowing tributaries to water quality and phytoplankton assemblages in the Mooi River. Method: Physico-chemical environmental variables were compared with water quality objectives and known limits to assess general water quality in the Mooi River over a one-year period. Water quality and phytoplankton in tributaries were compared to that at sites upstream and downstream from their inflows to determine the extent to which the tributaries affected the Mooi River. Multivariate analysis assisted in the interpretation of phytoplankton and physico-chemical data at the different sites. Results: Seven phytoplankton phyla were identified in the Mooi River. Diatoms and green algae were most dense and diverse. Cyanobacteria were responsible for various problems, especially in the Wasgoedspruit where they dominated and reached high densities. Lowest phytoplankton density and diversity were found in the upstream and downstream sections of the river, while maximum density and diversity were found during summer in the middle reaches. The inflow of tributaries, especially the Wasgoedspruit, had a pronounced effect on water quality downstream. Phytoplankton density and diversity were less affected than chemical variables, especially nutrient concentrations. Conclusion: Various land use activities surrounding the Mooi River's tributaries contributed to a deterioration of water quality in the main stream of the Mooi River. [ABSTRACT FROM AUTHOR]

Wetlands within the catchments of water supply dams have potential to make important contributions to water-related ecosystem services, particularly water quality enhancement. Wetlands are facing growing threats and continuing degradation. There have been limited attempts at evaluating the contribution of South African wetlands, and their rehabilitation, for water quality enhancement and other water-related ecosystem services. A comprehensive and integrated wetland services economic assessment determined the value of the Vyeboom Wetland in the catchment of the Theewaterskloof Dam. The water of this dam is a significant contributor to the City of Cape Town's water supply. The economic valuation model integrates hydrological, catchment status and economic models, with a long-term (80-year monthly) wetland water balance from a calibrated hydrological model as a driver for the nutrient removal aspect. The economic valuation builds on a water quality enhancement model, based on the minimisation of indirect use replacement cost principle, supplemented by a sediment retention and carbon storage assessment. The capability of the economic valuation model is illustrated by assessing the rehabilitation of a 25-ha area in the Vyeboom Wetland, which is currently intact, but is under threat of being severely degraded by the advancing erosion headcut. It was assumed that the current state of the Vyeboom Wetland is almost pristine (only 1 ha degraded), but that a further 24 ha would degrade over a period of 50 years, following spatial changes over time. By balancing the total investment in offsetting the potential loss in benefits, it is evident that an amount of 2.5 million ZAR could be afforded for rehabilitation. If, instead of a logistic degradation profile, the wetland is assumed to already be in a state of accelerated deterioration, the rehabilitation project budget for Vyeboom Wetland will increase once the other intrinsic benefits described are considered in the analysis. [ABSTRACT FROM AUTHOR]

The Eastern Basin chemical acid mine drainage (AMD) treatment plant is one of the world's largest highdensity sludge (HDS) plants, and came into operation in August 2016. The plant is situated near the inoperative Grootvlei Mine in Springs, South Africa, and upstream of the Blesbokspruit Wetland, a former Ramsar Wetland of International Importance, now on the Montreux Record. Since being in operation it has had a major influence on surface water quality along the wetland area. The plant was constructed to mitigate the anticipated decant of AMD water from the abandoned Grootvlei Mine into the Blesbokspruit Wetland. Making use of the BACI (Before-After-Control-Impact) design, this study compares surface water quality of the Blesbokspruit upstream (control site) and downstream (impact site) of the treatment plant for 3-year periods before and after it came into operation. Quarterly water quality data (aluminium, ammonia, chloride, conductivity, dissolved oxygen, fluoride, iron, magnesium, manganese, nitrate, pH, phosphate, sodium and sulphate) from 2013--2019 were used for 5 historical Rand Water monitoring sites along the Blesbokspruit. The current HDS treatment process has negatively influenced conductivity, chloride, magnesium, sodium and sulphate levels downstream. Since the commissioning of the treatment plant, the levels of these parameters have increased significantly. Notably, conductivity and sulphate have reached the management range defined as 'unacceptable' within the framework set out by the Blesbokspruit Forum (which is less stringent than the national guidelines for aquatic ecosystems), with potential impacts on salinization of the Vaal Barrage downstream. However, the significant reduction of iron, ammonia and phosphate concentrations downstream of the plant may be a combined beneficial effect of dilution by increased discharge from the plant and the wetland removing these contaminants. These results highlight the need for further research into possible secondary treatment and desalinisation mechanisms and the potential ecological and downstream water supply implications of increasing salinity within the area. [ABSTRACT FROM AUTHOR]

Background: The understanding of the impact of land-use on the dynamics of phytoplankton assemblages during varying climate conditions on rivers is limited. Objective: To determine the impact of land-use types and flow on phytoplankton assemblages in the Sabie River. Methods: The relationships between land-use patterns, water quality and phytoplankton assemblages were analysed using canonical correspondence analyses (CCA). Results: Six main land-use types could be distinguished in the eight identified sub-catchments of the river. The CCA results showed that the land-use had a stronger correlation with phytoplankton classes during the higher flow conditions than during low flow conditions. The forestry land-use type had the strongest correlation with nitrate-nitrite concentrations in the Sabie River. Chlorophyll-a concentrations were higher during 2016, and a slightly lower number of genera were observed for the class Chlorophyceae. During 2017 the number of genera of the class Cyanophyceae decreased together with chlorophyll-a and total cell concentrations. Conclusion: Low flow conditions favoured filamentous genera that are common to mesotrophic conditions while higher flow conditions favoured single-celled small genera more common to oligotrophic waters with higher disturbance. This study showed that flow has the potential to enhance the impact of land-use on phytoplankton community dynamics in a river system and thereby may have further impacts on the health and activities of surrounding communities. [ABSTRACT FROM AUTHOR]

Background: Although the Kruger National Park (KNP) is a protected area, it is not exempted from anthropogenically induced impacts, which often compromise river water flow and quality. Measures of river water quality in South Africa have conventionally been based on water chemistry as well as different ecological indicator groups such as fish and macroinvertebrates. Diatoms have been shown to be useful indicators of changes in water quality resulting from pollution and land-use impacts. Objectives: To determine the applicability of diatoms for hind-casting water quality in the KNP and to compare recent diatom community composition with those from the 1980s. Methods: In this study, pH and electrical conductivity (EC) were used to evaluate temporal changes in water quality of three rivers within the KNP. Additionally, we made use of historic diatom samples from three of the five perennial rivers to evaluate if diatom communities reflected changes in water conditions between 1983 and 2015. Results: Diatom community structure was significantly different between 1983 and 2015. Diatom-based index scores (SPI) indicated an improvement in water quality for the Letaba and Olifants rivers. Conclusion: Diatoms were shown to be useful indicators of current water quality and are also useful for determining temporal changes. [ABSTRACT FROM AUTHOR]

Background: Effluents from agricultural activities, metal and peat mining, urban and industrial areas, informal settlements and wastewater treatment plants all influence tributaries feeding the Mooi River. All these land uses ultimately result in a deterioration of water quality in the Mooi River. Objectives: The main objective was to relate the effects of inflowing tributaries to water quality and phytoplankton assemblages in the Mooi River. Method: Physico-chemical environmental variables were compared with water quality objectives and known limits to assess general water quality in the Mooi River over a one-year period. Water quality and phytoplankton in tributaries were compared to that at sites upstream and downstream from their inflows to determine the extent to which the tributaries affected the Mooi River. Multivariate analysis assisted in the interpretation of phytoplankton and physico-chemical data at the different sites. Results: Seven phytoplankton phyla were identified in the Mooi River. Diatoms and green algae were most dense and diverse. Cyanobacteria were responsible for various problems, especially in the Wasgoedspruit where they dominated and reached high densities. Lowest phytoplankton density and diversity were found in the upstream and downstream sections of the river, while maximum density and diversity were found during summer in the middle reaches. The inflow of tributaries, especially the Wasgoedspruit, had a pronounced effect on water quality downstream. Phytoplankton density and diversity were less affected than chemical variables, especially nutrient concentrations. Conclusion: Various land use activities surrounding the Mooi River's tributaries contributed to a deterioration of water quality in the main stream of the Mooi River. [ABSTRACT FROM AUTHOR]

Rivers in the North West Province (NWP) of South Africa are polluted by various anthropogenic activities that are associated with agricultural, domestic, industrial, and mining activities. Pollutants and effluent resulting from these activities impact the physico-chemical and biological characteristics of river water. More particularly, domestic and agricultural pollution has been associated with the occurrence of pathogenic yeast species in water. The aim of this study was to determine physico-chemical parameters, yeast levels, and the antifungal susceptibility of pathogenic yeasts in river water. Physico-chemical parameters and yeast levels were determined using standard procedures. Yeasts were identified by biochemical tests and 26S rRNA gene sequencing. Disc diffusion antifungal susceptibility tests were conducted on identified potential pathogenic yeasts. Physico-chemical parameters were within target water quality ranges (TWQR) for livestock farming but were mostly out of range for irrigation. Yeast levels (incubation at 37°C) ranged from 363 to 1 778 CFU/L. There were significant differences (p < 0.05) in the physico-chemical parameters and yeast levels between some seasons and among the river systems under study. A positive association was observed between temperature, COD and yeast levels in all the river systems. Ascomycetes, which were the most prevalent isolates, were identified as Candida spp. (35%), Pichia spp. (13%), Cyberlinera spp. (12%), Meyerozyma spp. (11%), Clavispora spp. (10%), Saccharomyces spp. (6%), Kluyveromyces spp. (5%), Yamadazyma spp. (4%), Trichosporon spp. (3%), and Wickerhamomyces spp. (1%). Antifungal resistance of the potential pathogenic yeasts was as follows: flucytosine and miconazole (100%) > fluconazole (78.5%) > econazole, and miconazole and ketoconazole (49.6%) > nystatin (15.2%). The river water systems explored in the study are used for agricultural, domestic and recreational purposes. Direct contact with the water, especially by immune-compromised people, may pose a health threat and should be further investigated. [ABSTRACT FROM AUTHOR]