Lake Mcilwaine: The Eutrophication and Recovery of a Tropical African Man-Made Lake (Monographiae Biologicae, 49)

'And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters. ' Genesis 1:6 Lake McIlwaine is a man-made lake. It was formed in 1952 by the Hunyani­ poort Dam and is situated on the Hunyani River some 37 km southwest of Salisbury\* in the Republic of Zimbabwe\*\*. It is a lake of many aspects: being a popular recreational site, the City's primary water supply reservoir (and the fourth largest impoundment in Zimbabwe), a source of irrigation water to downstream farms, an important fishery, and, until the 1970s, the receptacle of Salisbury's sewage effluent. It is, in short, typical of so many 'urban' lakes in Africa and throughout the world. Lake McIlwaine is also unique, to my knowledge: being amongst the first of the major man-made lakes on the continent to suffer from what is known as cultural eutrophication, and the first to be r:ehabilitated to a mesotrophic state through a rational programme of lake management. This volume synthesizes this process of eutrophication and recovery in terms of the geology and geography (Chapter 2), physics (Chapter 3), chemistry (Chapter 4) and biology (Chapter 5) of the lake, and, whilst discussion of the trophic relationships between these components is beyond the scope of this monograph, discusses its utilisation, conservation and management (Chapter 6). \* Subsequent to writing, the name of the Zimbabwean capital was changed to Harare on 18 April 1982. - Ed. Front Matter....Pages I-XII The creation of Lake McIlwaine: history and design....Pages 1-9 Land use survey of the Upper Hunyani catchment....Pages 11-22 Physical limnology....Pages 23-34 The hydrology of the Lake McIlwaine catchment....Pages 34-41 Water chemistry and nutrient budgets....Pages 43-59 The sediments....Pages 59-71 The effects of urban run-off....Pages 71-94 Insecticides in Lake McIlwaine, Zimbabwe....Pages 94-99 An SEM study of bacteria and Zooplankton food sources in Lake McIlwaine....Pages 101-106 Phytoplankton, primary production and nutrient limitation....Pages 106-133 Zooplankton and secondary production....Pages 133-136 Aquatic macrophytes and Eichhornia crassipes ....Pages 137-144 The benthic fauna of Lake McIlwaine....Pages 144-155 The fish of Lake McIlwaine....Pages 156-188 Avifauna of Lake McIlwaine....Pages 188-194 Water pollution: perspectives and control....Pages 195-201 Water supply and sewage treatment in relation to water quality in Lake McIlwaine....Pages 202-217 Fisheries....Pages 217-220 Recreation....Pages 221-226 Research: perspectives....Pages 227-231 Bibliography....Pages 233-240 Back Matter....Pages 241-251