Filamentous freshwater macroalgae in South Africa — a literature review and perspective on the development and control of weed problems

Studies on freshwater filamentous algae have not been undertaken in South Africa for some thirty years. Early investigations were mainly of a taxonomic nature and ecological information is virtually non-existent. However, in the recent years the spread of urban settlement and increasing demand for both industrial and domestic water have highlighted the problems facing current water supplies. Irrigation systems in particular have suffered increasing interferences from filamentous algal blooms, mainly Cladophora glomerata. As nutrient loads have increased in impoundments and rivers, the presence of this alga has become more obvious, causing decreased water flow in canals and an escalation in costs associated with its control. Copper sulphate and predosing with commercial sulphuric acid to reduce pH are now the commonest control method in most of the irrigation systems. A synopsis of current conditions is presented and proposed avenues of research are discussed.