Magister Scientiae - MSc / A study of the microbial diversity in sediments of the Great Berg River estuary is carried out using modern molecular phylogenetic methods. The aim of this study was to determine the effect of (pollution by) the effluents of the fish industry on the composition of the microbial community in the sediments. The diversity in microbial groups of sediment samples that received wastewater from the local fishing industry was investigated by a PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) approach and compared to an unaffected site. / South Africa

<p>A study of the microbial diversity in sediments of the Great Berg River estuary is carried out using modern molecular phylogenetic methods. The aim of this study was to determine the effect of (pollution by) the effluents of the fish industry on the composition of the microbial community in the sediments. The diversity in microbial groups of sediment samples that received wastewater from the local fishing industry was investigated by a PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) approach and compared to an unaffected site.</p>

<p>A study of the microbial diversity in sediments of the Great Berg River estuary is carried out using modern molecular phylogenetic methods. The aim of this study was to determine the effect of (pollution by) the effluents of the fish industry on the composition of the microbial community in the sediments. The diversity in microbial groups of sediment samples that received wastewater from the local fishing industry was investigated by a PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) approach and compared to an unaffected site.</p>

South Africa’s freshwater quality and quantity is declining and consequently impacting on the ecological health of these ecosystems, due to increased agricultural, urban and industrial developments. The River Health Programme (RHP) was designed for monitoring and assessing the ecological health of freshwater ecosystems in South Africa, in order to effectively manage these aquatic resources. The RHP utilises biological indicators such as in-stream biota as a structured and sensitive tool for assessing ecosystem health. Although the RHP has been widely implemented across South Africa, no attempts have been made to explore microbial ecology as a tool that could be included as one of the RHP indices. This study used selected microbial responses and water physico-chemical parameters to assess the current water quality status of the Buffalo River. This study showed that water quality impairments compounded in the urban regions of King William’s Town and Zwelitsha and also downstream of the Bridle Drift Dam. The results also showed that the lower and the upper catchments of the Buffalo River were not significantly different in terms of water physico-chemistry and microbiology, as indicated by low stress levels of an NMDS plot. Though similarities were recorded between impacted and reference sites, the results strongly showed that known impacted sites recorded the poorest water physico-chemistry, including the Yellowwoods River. However, the Laing Dam provided a buffer effect on contributions of the Yellowwoods River into the Buffalo River. Multivariate analysis showed that microbial cell counts were not influenced by water physico-chemical changes, whilst microbial activity from the water and biofilm habitats showed significant correlation levels to water physico-chemical changes. This study demonstrated that further investigations towards exploitation of microbial activity responses to water physico-chemical quality changes should be channelled towards the development of microbiological assessment index for inclusion in the RHP.

The main aim of this study was to assess the “top-down” and “bottom-up” control of bacterial production in the small temporarily open/closed East Kleinemonde Estuary, situated on the south-eastern coastline of southern Africa. Spatial and temporal patterns in bacterial abundance, biomass and production and the importance of abiotic and biotic factors were investigated over the period May 2006 to April 2007. The trophic interactions between bacteria, phytoplankton, nanoflagellates (< 20 μm), microzooplankton (< 200 μm) and mesozooplankton (< 2 000 μm) were investigated during winter and summer. Bacterial abundance, biomass and production ranged between 1.00 × 10⁹ and 4.93 × 10⁹ cells 1⁻¹, 32.4 and 109 μg C 1⁻¹ and 0.01 and 1.99 μg C 1⁻¹ h⁻¹, respectively. With a few exceptions there were no spatial patterns in the values. Bacterial abundance, biomass and production, however, demonstrated a distinct temporal pattern with the lowest values consistently recorded during the winter months. Nanoflagellate and bacterial abundances were significantly correlated to one another (lower reaches: r = 0.818, p < 0.001; middle reaches: r = 0.628, p < 0.001; upper reaches: r = 0.484, p < 0.05) suggesting a strong predator-prey relationship. The frequency of visibly infected bacterial cells and the mean number of virus particles within each bacterial cell during this study demonstrated no temporal or spatial patterns and ranged from 0.5 to 6.1 % and 12.0 to 37.5 virus particles per bacterium, respectively. Viral infection and lysis was thus a constant source of bacterial mortality throughout the year. The estimated percentage of bacterial production removed by viral lysis ranged between 7.8 and 88.9% of the total which suggests that viral lysis represented a very important source of bacterial mortality during this study. The biological interactions between the selected components of the plankton community demonstrated that among the heterotrophic components of the plankton, the nanoflagellates were identified as the most important consumers of bacteria and small phytoplankton cells (< 20 μm). In the presence of microzooplankton the impact of the nanoflagellates on both the bacteria and phytoplankton was reduced, indicating that larger heterotrophs were preying upon the nanoflagellates. Mesozooplankton, however, appeared to exert the greatest impact on nanoflagellates. In the cascading experiments, the data suggest that mesozooplankton consume nanoflagellates, which resulted in a decrease in the predation impact of these organisms on the bacteria. This result is consistent with predator-prey cascades. The presence of the larger heterotrophs therefore, mediates the interactions between the primary bacterivores, the nanoflagellates, and the bacteria within the temporarily open/closed East Kleinemonde Estuary.

Water Quality Management is one of the critical challenges currently facing South Africa. The triad of water resource management, socio- economic development and environmental sustainability are key issues that require balance and compromise. The effects of anthropogenic activities on the Blesbokspruit catchment were examined. Water samples were collected from nine strategically selected sites along the stream for a period of ten months in six weekly intervals and analysed for physio-chemical, selected trace metals and microbial entities. Results revealed that variables of concern were Electrical Conductivity (EC), Total Suspended Solids (TSS), Nitrates, Phosphates, Sulphates and Chemical Oxygen Demand (COD). Mean levels of these parameters in this order ranged from 93.0-146.63mS/m; 11.25-39mg/L; 0.16-2.01mg/L; 0.5-0.96mg/L; 118.63-379.5mg/L and 15.0-34.0mg/L respectively. Levels of E. coli and F. coliforms also ranged from 19.13- 43999.125 cfu/100mL and 20.63-16878.5 cfu/100mL respectively which were of concern. Levels of analysed trace metals were tolerable except for Fe with a range of 0.04- 0.73mg/L. Generally, the results from this study indicate that the river is contaminated and therefore not suitable for direct human consumption as well as for irrigation purposes.

Water Quality Management is one of the critical challenges currently facing South Africa. The triad of water resource management, socio- economic development and environmental sustainability are key issues that require balance and compromise. The effects of anthropogenic activities on the Blesbokspruit catchment were examined. Water samples were collected from nine strategically selected sites along the stream for a period of ten months in six weekly intervals and analysed for physio-chemical, selected trace metals and microbial entities. Results revealed that variables of concern were Electrical Conductivity (EC), Total Suspended Solids (TSS), Nitrates, Phosphates, Sulphates and Chemical Oxygen Demand (COD). Mean levels of these parameters in this order ranged from 93.0-146.63mS/m; 11.25-39mg/L; 0.16-2.01mg/L; 0.5-0.96mg/L; 118.63-379.5mg/L and 15.0-34.0mg/L respectively. Levels of E. coli and F. coliforms also ranged from 19.13- 43999.125 cfu/100mL and 20.63-16878.5 cfu/100mL respectively which were of concern. Levels of analysed trace metals were tolerable except for Fe with a range of 0.04- 0.73mg/L. Generally, the results from this study indicate that the river is contaminated and therefore not suitable for direct human consumption as well as for irrigation purposes.