M.Sc. (Zoology) / National water quality monitoring in South Africa has in the past mainly focused on measuring physical and chemical variables. However, it is increasingly realised that measuring physical and chemical variables on their own cannot provide an accurate account of the general "health" of an aquatic ecosystem. Biological communities, on the other hand, are accurate indicators of overall environmental conditions. Water quality management must, therefore, rely on comparative data for both chemical composition and biological effects. In fact, it appears as if biological monitoring (biomonitoring) is worldwide becoming a primary tool in assessing environmental condition and verifying compliance with effluent discharge. This study classified different biomonitoring approaches and techniques under bioassessment (referring to the field oriented biomonitoring protocols which make use of biotic indices to assess water quality); bioassays (toxicity tests which is usually laboratory-based); behavioural bioassays (including aspects such as early warning systems, and preference and avoidance studies); bacteriological studies (the monitoring of certain microbes to allow the detection of faecal contamination); measurement of bioaccumulation (referring to the methods by which the uptake and retention of chemicals in the body of an organism can be monitored); and fish pathology (fish health studies dealing with the causes, processes and effects of disease). Habitat assessment and evaluation was identified as an essential part of any biosurvey. There can be little uncertainty about the mutual dependence of habitat quality, biological health and chemical characteristics of water in the environment. Relative habitat condition, as the principal determinant of attainable biological potential, should set the context for interpreting the results of a biosurvey and can be used as a general predictor of biological condition. Chemistry can further help to explain and characterise certain impacts. The Crocodile River, Eastern Transvaal, was selected for conducting a case study. The SASS2 rapid bioassessment protocol, as well as a habitat quality index (Hal) was used during five consecutive biosurveys. From the results obtained in this study, it appears as if biomonitoring can be used to good effect in overall environmental assessment. The SASS2 index appeared to be both a robust and sensitive indicator of environmental condition. Application of the SASS2 technique on a regional or even national basis should be feasible with regard to simplicity and practicality. It is also cheaper and less labour intensive than comprehensive chemical monitoring. However, bioassessments should not replace but rather compliment chemical and physical monitoring.

The prevention of outbreaks of waterborne diseases remains a major challenge to public health service providers globally. One of the major obstacles in this effort is the unavailability of on-line and real-time methods for rapid monitoring of faecal pollution to facilitate early warning of contamination of drinking water. The main objective of this study was to develop a β-glucuronidase (GUD)-based method that could be used for the on-line and real-time monitoring of microbial water quality. GUD is a marker enzyme for the faecal indicator bacteria Escherichia coli. This enzyme breaks down the synthetic substrate p-nitrophenyl-β-D-glucuronide (PNPG) to D-glucuronic acid and p-nitrophenol (PNP), which turns yellow under alkaline pH. The enzymatically produced PNP was used to detect GUD activity. In situ GUD assays were performed using running and stagnant water samples from the Bloukrans River, Grahamstown, South Africa. The physico-chemical properties of environmental GUD were determined, after which a liquid bioprobe and a microbial biosensor modified with Moraxella 1A species for the detection of the enzyme activity were developed. In order to determine the reliability and sensitivity of these methods, regression analyses for each method versus E. coli colony forming units (CFU) were performed. The storage stabilities of the bioprobe and biosensor were also investigated. The physico-chemical properties of in situ GUD were different from those of its commercially available counterpart. The temperature optimum for the former was between 35 and 40 °C while for the latter it was 45 °C. Commercial (reference) GUD had a pH optimum of 8.0 while the environmental counterpart exhibited a broad pH optimum of between pH 5.0 and 8.0. The liquid bioprobe had a limit of detection (LOD) of GUD activity equivalent to 2 CFU/100 ml and a detection time of 24 h. The method was less labour intensive and costly than the culturing method. The liquid bioprobe was stable for at least four weeks at room temperature (20 ± 2 °C). The biosensor was prepared by modifying a glassy carbon electrode with PNP degrading Moraxella 1A cells. The biosensor was 100 times more sensitive and rapid (5-20 min) than the spectrophotometric method (24 h), and was also able to detect GUD activity of viable but non-culturable cells. Thus it was more sensitive than the culturing method. Furthermore, the biosensor was selective and costeffective. The possibility of using a Pseudomonas putida JS444 biosensor was also investigated, but it was not as sensitive and selective as the Moraxella 1A biosensor. The Moraxella biosensor, therefore, offered the best option for on-line and real-time microbial water quality monitoring in South African river waters and drinking water supplies.

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