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Investigation of the Effectiveness of Techniques Deployed in Controlling

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Investigation of the Effectiveness of Techniques Deployed in Controlling Investigation of the effectiveness of techniques deployed in controlling cyanobacterial growth in Rietvlei Dam, Roodeplaat Dam and Hartbeespoort Dam in Crocodile (West) and Marico Water Management Area. by Noloyiso Xoliswa Mbiza submitted in accordance with the requirements for the degree of Master of Science in the subject Environmental Management at the University of South Africa Supervisor: Dr. Mike Silberbauer February 2014 Summary Eutrophication is a nutrient enrichment of dams and lakes. Increased eutrophication in dams results in blooms of cyanobacteria. Cyanobacteria are troublesome as they form massive surface scums, impart taste and odour to the water. Some strains of cyanobacteria such as Microcystis aeruginosa are dangerous to humans and animals. They produce toxins that can kill animals drinking the contaminated water and have also been implicated in human illnesses. The study investigated the effectiveness of techniques deployed in controlling cyanobacterial growth in Rietvlei, Roodeplaat and Hartbeespoort Dams. This was done by interpreting data from April 2010 to March 2012. The conditions in the three dams show that Microcystis produced toxins in the summer season and all the variables analysed were favourable for the production of toxins. The methods deployed to rehabilitate the dams do not completely solve the problems of toxins experienced by the dams. Keywords: Cyanobacteria, Eutrophication, Microcystis, Phosphorus, Total microcystin, Toxins i Declaration Student Number: 48944246 I declare that, Investigation of the effectiveness of techniques deployed in controlling cyanobacterial growth in Rietvlei Dam, Roodeplaat Dam and Hartbeespoort Dam in Crocodile (West) and Marico Water Management Area is my own work and that all the sources that I have used or quote have been indicated and acknowledged by means of complete references. SIGNATURE DATE (Ms) ii Acknowledgements I wish to thank: o My God who has been with me throughout the research. o My supervisor, Dr. Mike Silberbauer, for the help, encouragement and guidance throughout the research. o My colleague, Brendan Hohls for taking sampling procedure photos. o My colleagues, the sampling team for taking samples at the dam wall of each dam. o My colleagues, analytical services personnel for analysing the samples. o My family for the love, encouragement, support and understanding throughout the research iii Dedication This research is dedicated to my God who has been the driving force behind all my achievements. iv Contents Summary ..............................................................................................................i Declaration ...........................................................................................................ii Acknowledgements ..............................................................................................iii Dedication ............................................................................................................iv Contents ...............................................................................................................v List of Figures ......................................................................................................vii List of Tables .......................................................................................................x Glossary ...............................................................................................................xi Chapter One: Background ................................................................................................1 1.1 Background ....................................................................................................1 1.2 Problem statement ..........................................................................................5 1.3 Research objectives ........................................................................................5 1.4 Scope of the research ......................................................................................6 1.4.1 Roodeplaat Dam ...........................................................................9 1.4.2 Rietvlei Dam .................................................................................11 1.4.3 Hartbeespoort Dam .......................................................................13 1.5 Limitations of the study ..................................................................................16 1.6 Research plan and frame .................................................................................16 Chapter Two: Literature Review ......................................................................................17 2.1 Cyanobacteria and toxins..................................................................................17 2.2 Why is Eutrophication difficult to manage? ....................................................19 2.3 Sources of phosphorus which give rise to eutrophication in South African Waters................................................................................................................20 2.4 Ecological strategy for eutrophication control ..................................................20 2.5 Cyanobacteria in South Africa ..........................................................................21 2.6 Routes of exposure of cyanobacterial toxins .....................................................22 2.7 Health effects associated with cyanobacterial toxins ........................................22 v 2.8 Roodeplaat Dam rehabilitation ..........................................................................22 2.9 Rietvlei Dam rehabilitation ................................................................................23 2.10 Hartbeespoort Dam remediation practices .......................................................23 2.11 Management of water resources ......................................................................24 2.12 Management of eutrophication ........................................................................25 2.13 Principles for managing dams ..........................................................................26 Chapter Three: Research Methodology ...............................................................................27 3.1 Research methods ..................................................................................................27 Chapter Four: Results...........................................................................................................32 4 Results .....................................................................................................................32 4.1 Roodeplaat Dam ...................................................................................................32 4.2 Rietvlei Dam .........................................................................................................40 4.3 Hartbeespoort Dam ..............................................................................................48 Chapter Five: Discussion, conclusion, recommendations references and Appendix ............................................................................................................................56 5.1 Discussion ............................................................................................................56 5.1.1 Roodeplaat Dam .............................................................................................57 5.1.2 Rietvlei Dam ...................................................................................................58 5.1.3 Hartbeespoort Dam .........................................................................................59 5.2 Conditions in the three Dams .................................................................................60 5.3 Conclusion ..............................................................................................................61 5.4 Recommendations ..................................................................................................62 5.5 References ..............................................................................................................63 Appendixes .........................................................................................................................70 vi List of Figure Figure 1: Map showing the selected dams of the study area Figure 2: Map showing land cover in Roodeplaat Dam Catchment area Figure 3: Representation (%) of land cover in Roodeplaat Dam Figure 4: Map showing land cover in Rietvlei Dam Catchment area Figure 5: Representation (%) of land cover in Rietvlei Dam Figure 6: Map showing land cover in Hartbeespoort Dam Catchment area Figure 7: Map showing Sewage works in Hartbeespoort Dam catchment area Figure 8: Representation (%) of land cover in Hartbeespoort Dam Figure 9: (a) shows lowering the Secchi disk for checking light transparency, (b) lowering the Secchi disk until it cannot be seen and (c) reading Secchi depth so as to record the light transparency of the water column Figure 10: (a) shows vertically lowering the five meter hosepipe into the water, (b) lowering the pipe at five meters deep, (c) and (d) five meter pipe full and pulled up for pouring in bucket and then to sampling bottles Figure 11: (a) Plastic bottle used to collect inorganic water samples, (b) 1 litre bottle used to collect hydrobiological samples and (c) glass bottle used to collect microcystin sample Figure 12: Total phosphorus concentration in
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