Sandra Barnard

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• PhD Plant Physiology
• Professor at North-West University

Increasing livestock densities and more severe drought events challenge sustainable management in South Africa’s semi-arid savannas. Effective mitigation strategies require accurate assessments of livestock foraging behaviour. By utilising high-throughput sequencing technology, this study evaluated the use of a dual-locus metabarcoding approach (tr...

Serpentine soils are characterized by nutrient imbalances and high levels of potentially toxic metals (PTMs). These soils host depauperate plant communities of species with specialized adaptations. Initial studies showed that South African serpentine soils harbor distinct biocrust algal and cyanobacterial species compared to adjacent non-serpentine...

Success of a metabarcoding study is determined by the extent of taxonomic coverage and the quality of records available in the DNA barcode reference database used. This study aimed to create an rbcL and a trnL (UAA) DNA barcode sequence reference database of plant species that are potential herbivore foraging targets and commonly found in semi-arid...

The success of a metabarcoding study is determined by the extent of taxonomic coverage and the quality of records available in the DNA barcode reference database used. This study aimed to create an rbcLa and trnL (UAA) DNA barcode sequence reference database of plant species that are potential herbivore foraging targets and commonly found in semi-a...

A unique opportunity to study the sexual reproduction of Chlamydomonas proboscigera was presented when this species reached high densities in the Vaal River, South Africa during 2019. A peculiar and unique way of sexual reproduction in C. proboscigera was revealed for the first time and differs from earlier knowledge on the sexual reproduction of t...

Coral reefs are diverse and productive but sensitive ecosystems. Due to the impact of climate change, these organisms are in danger of dying out, mainly through the process of coral bleaching, which is the process by which zooxanthellae (algal endosymbionts) are expelled from their respective coral hosts, causing the coral to lose colour and become...

Chlamydomonas proboscigera is a unicellular, ellipsoidal-to-spherical chlorophyte distinguished by a flattened papilla, a large spherical pyrenoid and a disc-shaped stigma located anterior in a cup-shaped chloroplast. The species is common in eutrophic water, but also occurs in terrestrial environments, such as soils. Previously, Chlamydomonas prob...

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 phytoplankto...

• Comparison of 2 differentially polluted streams, Vaal River and Koekemoerspruit • Significant correlation between physical chemical parameters and phytoplankton taxa • Chlorophyceae (Scenedesmus spp) dominated in Vaal River • Cyanophyceae (Nitszchia spp) dominated in Koekemoerspruit

When purifying water for potable use, wastewater is generated, due to the class of the water treatment plant and the quality of the source water. Midvaal Water Company recycled wastewater that included residue from the dissolved air flotation (DAF), sedimentation and filtration processes in an attempt to save water and reduce costs. The aim of this...

Abstract The Koekemoerspruit is a possible pollution source of the Middle Vaal River, an important drinking water source in South Africa. This case study aimed to establish the water quality of the Koekemoerspruit, to evaluate the impact of the Koekemoerspruit on the Vaal River, and to use this information to iden-tify shortcomings in the monitorin...

Phytoplankton synthesize biomolecules through the process of photosynthesis, and the decomposition of these molecules causes odors in water. While the freshwater dinoflagellate Ceratium hirundinella is well known for causing a variety of odors in water, the organic acid profile of this specimen has not been studied, and the compounds causing the od...

Pre-commercialization studies on environmental biosafety of genetically modified (GM) crops are necessary to evaluate the potential for sexual hybridization with related plant species that occur in the release area. The aim of the study was a preliminary assessment of factors that may contribute to gene flow from sugarcane (Saccharum hybrids) to in...

Climate and geography can influence biological soil crust (BSC) community composition, but local heterogeneity in variables such as soil characteristics or microclimate gradients can also impact cryptogamic diversity. Heavy metals and nutrient imbalances in serpentine soils are known to influence the distributions of higher plants, but cryptogamic...

Most of the ultramafic sites had higher chlorophyll-a content and had a more diverse algal component and less diverse fungal and bacterial component, than the mafic sites in the same geographical area. Although results did not show a clear difference between the composition of the bacterial, fungal and algal populations of ultramafic and non-ultram...

We compared the cryptogamic composition of ultramafic and non-ultramafic soils to determine how soil characteristics can influence biological soil crust (BSC) community composition. Samples from ultramafic and non-ultramafic soils were enriched with liquid growth media to determine the algal and cyanoprokaryote genera present. Total genomic DNA was...

Unit processes of a conventional water purification facility are designed to remove suspended material from source water (both inorganic and organic impurities). Organic substances in source water include phytoplankton species (algae and cyanobacteria) that are generally negatively charged on the surface of the cells. The zeta potential (ZP) of alg...

Midvaal Water Company treats hypertrophic water abstracted from the Vaal River to supply bulk wholesome potable water to their consumers in compliance with the South African National Standard (SANS) 241:2015 for drinking water. The facility incorporates conventional and advanced treatment processes. The aims of the study were to identify how the wa...

Cyanobacteria are responsible for many problems in drinking water treatment works (DWTW) because of their ability to produce cyanotoxins that potentially can have an adverse effect on consumer health. Therefore, the monitoring of cyanobacteria in source waters entering DWTW has become an essential part of drinking water treatment management. Manage...

Algal genera such as Carteria, Chlamydomonas, Chlorogonium, Cryptomonas, Ceratium, Peridinium and Euglena are motile and may disrupt unit processes and cause water treatment problems. Algal species belonging to these motile algal genera are known to interfere with coagulation and flocculation unit processes which are the main processes for algal re...

Cyanobacteria are responsible for many problems in drinking water treatment works (DWTW) because of their ability to produce cyanotoxins that potentially can have an adverse effect on consumer health. Therefore, the monitoring of cyanobacteria in source waters entering DWTW has become an essential part of drinking water treatment management. Manage...

The dinoflagellate, Ceratium hirundinella (C. hirundinella) cells are known to cause many problems when source water due for purification contains relatively high concentrations. The objective of this study was to investigate strategies for the effective and simultaneous removal of turbidity and C. hirundinella cells using turbidity and total photo...

An ecologically healthy Mooi River system is important for maintaining the quality of potable water of Potchefstroom and surrounding areas. However, this system is under constant threat from anthropogenic pollution arising from both agricultural and mining activities in its catchment. A survey of planktonic algal and cyanoprokaryote assemblages in...

Vetiver grass Chrysopogon zizanioides (L) Roberty) is sterile and only regenerates vegetatively from clumps of the rootstock. Together with its vigorous and deep root system this makes it ideal for use in soil remediation and erosion control. In South Africa, Hydromulch (Pty) Ltd is part of the landscape, soil reclamation and erosion control indust...

The South African impoundments of Hartbeespoort and Roodeplaat experience excessive blooms of Microcystis species each year. Microcystins, produced primarily by strains of cyanobacteria belonging to the genera Microcystis, Anabaena and Planktothrix, are harmful cyanobacterial hepatotoxins. These bloom-forming cyanobacteria form toxic and non-toxic...

The Mooi River catchment, in particular the Wonderfonteinspruit (WFS), has been the subject of a large number of studies regarding significant pollution sources, generally attributed to mining in the area. However, very little is known about the hydrochemistry of the surface water of the Klerkskraal, Boskop and Potchefstroom Dams in the Mooi River...

Die Rietvleidam is Suid-Oos van die Metropool van Tshwane geleë en die dam se hoof bronvan water is die Hennopsrivier, sowel as vier ander klein nie-onderhoudende stroompies. Die Rietvleidam watersuiweringsaanleg (WSA) is aan die Ooste kant van die dam self geleë.

Boskopdam is een van verskeie damme wat in die Mooirivierstelsel in Noordwes-provinsievoorkom. Die konstruksie van die dam het in 1955 begin as gevolg van ‘n tekort aan besproeiingswater en is voltooi in 1959.

The aim of this study was to determine the efficacy of ozone in water purification processes at the Midvaal Water Company, which uses the hypertrophic Middle Vaal River for source water. It was found that pre- and intermediate ozonation had no significant effect on pH, conductivity, dissolved organic carbon (DOC) and total organic carbon (TOC). Chl...

In 1991 Oscillatoria simplicissima replaced Microcystis aeruginosa in the Vaal River, South Africa. This study explored the reason for this succession by looking at the photosynthetic performance of these two cyanoprokaryotes at different temperatures, light intensities and N:P ratios. Microcystis aeruginosa showed higher growth rates and chlorophy...

Oscillatoria limosa was identified using a polyphasic approach. Light microscopy and transmission electron microscopy studies revealed a filamentous organism without a sheath, with discoid cells and rounded apical cells. Gas vacuoles are absent and cells have prominent thylakoids and storage granules. Reproduction is by trichome fragmentation into...

Nearly complete 16S ribosomal RNA sequences from a strain isolated in the Vaal River, South Africa, commonly identified as "Oscillatoria simplicissima sensu PIETERSE & STEYNBERG 1993", as well as Planktothrix pseudagardhii NIVA CYA 153 were determined. Phylogenetic analysis of these species, together with P. pseudagardhii NIES 845T, Planktothrix ag...

The growth of the bloom forming cyanobacterial species Oscillatoria simplicissima Gomont from the Vaal River, South Africa, was studied under varying N and P concentrations. It was found that this species responds morphologically to N or P limitation by decreasing the length of its filaments. Especially in N-depleted treatments the length of the fi...

Development of cyanobacterial and green algal mass-occurrences in the eutrophied Vaal River (South Africa) has caused concern. The influence of various N and P concentrations and ratios on growth, chlorophyll-a concentration, alkaline and acid phosphatase activity of strains of two green algae, Chlamydomonas and Chlorella were studied. Chlamydomona...

Dinoflagellates are microalgae that often develop blooms in the marine and freshwater environments. Common bloom-forming genera in freshwaters are Ceratium, Peridinium, and Peridiniopsis. In July 2003 we observed mass development of Peridinium gatunense Nygaard in the planktonic community of Potchefstroom Dam, South Africa. This species was first d...

The isolation of high quality DNA from Acacia karroo Hayne is impeded by the release of secondary metabolites. The isolation method of Bousquet et al. (1990) was modified to include numerous CTAB extractions coupled with an increased buffer to tissue ratio and the addition of 5 M NaCl, yielding high quality DNA.

A cytokinin habituated non-organogenic callus line of Glycine max L. cv. Acme, was isolated. Cytokinins were detected in both non- and habituated calli. HPLC analysis indicated that the highest biological activity was associated with compounds that cochromatographed with zeatin and derivatives thereof. Cytokinin-like activity in the habituated call...

Activities of some key enzymes of glycolysis and sucrose metabolism were investigated in relation to the physiological growth stage in bean cell suspension cultures. Activities of sucrose synthase, pyrophosphate:fructose-6-phosphate phosphotransferase, ATP:fructose-6-phosphate phosphotransferase, UDP glucose pyrophosphorylase, acid and alkaline inv...

Thesis (M.Sc.) - University of the Orange Free State, 1992.