Human impact on lake ecosystems: the case of Lake Naivasha, Kenya

Abstract

Lake Naivasha is a wetland of national and international importance. However, it is under constant anthropogenic pressures, which include the quest for socioeconomic development within the lake ecosystem itself as well as other activities within the catchment. The lake is an important source of fresh water in an otherwise water-deficient zone. It supports a thriving fishery, an extensive flower-growing industry and geothermal power generation. It is home to a wide range of aquatic and terrestrial flora and fauna, including vegetation, birds, fish and mammals. The adjacent area is ideal for horticulture, which plays a crucial role in the development of both the local and national economy, providing employment to more than 30 000 people. The Lake Naivasha area produces up to 70% of Kenya's total horticultural output and contributes significant foreign exchange to the national economy. However, the lake and its surrounding areas are fragile ecosystems that face increasing threats from irrigated agriculture, water abstraction, the fast-growing Naivasha Township, and human population growth throughout the basin. Agricultural and livestock farming activities within the 3 376km² catchment area are also a threat to the lake ecosystem. This paper reviews some of the adverse socioeconomic activities that exert pressure on the lake, as well as bioindicator data that may be useful in assessing the overall quality of the lake as an important wetland ecosystem.

Keywords: agriculture, alien species, bioindicator species, environmental degradation, human activities, lake fisheries, Ramsar site, water abstraction, waterbirds, water resources

African Journal of Aquatic Science 2007, 32(1): 79–88