Environmental impacts of water quality change on beneficial uses of Lake Victoria.

The Lake Victoria Basin (LVB) has become a focal point of development in Kenya, thereby attracting intensive multiple land use which has accelerated environmental degradation through siltation, water pollution and changes in flooding frequency. In addition, multi-sectoral uses of water have created competition among various water users without due regard to the need for ecological sustenance or the needs of downstream users. This pattern poses serious management problems. The LVB is used as a source of food, energy, drinking and irrigation water, shelter, transport and as a repository for human, agricultural and industrial waste. With the population of the riparian communities growing at rates among the highest in the world, the multiple activities in the lake basin have increasingly come into conflict. This has contributed to rendering the lake environmentally unstable. The lake ecosystem has undergone substantial, and to some observers alarming changes, which have accelerated over the last three decades. Massive blooms of algae have developed, and come increasingly to be dominated by the potentially toxic blue-green variety. The distance at which a white disc is visible from the surface, (a transparency index measuring algal abundance or secchi depth), has declined from 5 m in the early 1930s to 1 m or less for most of the year in the early 2000s. Water-borne diseases have increased in frequency. Water hyacinth, absent as late as 1989, has choked important waterways and landings. Overfishing and oxygen depletion at lower depths of the lake threaten the artisanal fisheries and biodiversity (over 200 indigenous species are believed to be facing possible extinction). Scientists advance two main hypotheses for these extensive changes. First, the introduction of the Nile perch as an exotic species some 30 years ago has altered the food web structure; second, nutrient inputs from the adjoining catchments are causing eutrophication. Thus, although the lake and its fishery show the evidence of the dramatic changes in the lake basin over the past century, the lake is not the source of the problem. The problem has arisen in the surrounding basins through polluting activities of humans activity and the demand for fish.

Bibliographic Details

Main Authors:	Angweya, R., Okungu, J., Abuodha, J.O.Z., Hecky, R.E.
Format:	Book Section biblioteca
Language:	English
Published:	Lake Victoria Environment Management Project (LVEMP) 2005
Subjects:	Environmental impact, Man-induced effects, Pollution effects, Water quality, Overfishing,
Online Access:	http://hdl.handle.net/1834/7138
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