THE EFFECT OF WATER HYACINTH PROLIFERATION ON THE RIPARIAN COMMUNITIES: WINAM GULF Assignment: Environmental System Analysis
Fitsum Elias Kifeleyesus, Student Number:
THE EFFECTS OF WATER HYACINTH PROLIFERATION ON THE RIPARIAN COMMUNITY IN WINAM GULF 1. Introduction
THE EFFECT OF WATER HYACINTH PROLIFERATION ON THE RIPARIAN COMMUNITIES: WINAM GULF Student number: 36586 Water hyacinth (Eichhornia crassipes) is a floating neo-tropical Pontederiacea, which, over the past century, has been spread around the world by humans (Gopal, 1987). This aquatic plant has unique life cycle and survival strategies that have given it competitive edge over other species. Hence, it has extremely high growth habit and high productivity. Once it is introduced and colonizes an ecosystem, it causes a disruption in the environmental, social aspect as well as economic aspects of the riparian society. The plant is originated from the northern tropics of southern America and has disseminated very quickly in various tropical and sub-tropical countries of Latin America and the Caribbean, Africa, Southeast Asia and the Pacific. The presence of this plant in Lake Victoria reported for the first time in 1989 (Moorhouse et al. 2001). It was brought to the lake from Rwanda through the Kagara River.
Figure 1 Map of location of Winam Gulf Winam gulf, which is located in the Kenyan part of Lake Victoria East Africa, is known as the "lake within the lake". It is a kind of an inlet lake which is connected to the big Lake Victoria with a narrow canal which is known as Rusinga channel. This gulf has 550 km shorelines and stretches about 100 km east to west and 50 km north-south with a total surface area of 1400 Km2. The Gulf is comparatively shallow, having a recorded maximum and average depth of 68 m and 6 m. (Hughes and Hughes 1992). The gulf provides ecosystem services to the community such as, supply of drinking water, power generation, ﬁsheries and food security, transportation, and provision of other ecosystem goods and services. The location of Winam gulf (Lake Victoria) in the tropical region is a good environment for the spread of water hyacinth. Although it is not known exactly when the Water Hyacinth entered the
THE EFFECT OF WATER HYACINTH PROLIFERATION ON THE RIPARIAN COMMUNITIES: WINAM GULF Student number: 36586 gulf, the abundance of space, high nutrient flow, high solar energy and few natural enemies in the gulf have given a suitable environment for this plant to proliferate. These factors and the extensive growth nature of the plant enable water hyacinth to cover large area of the gulf. As a result of such rapid rate of expansion many parts of the gulf, such as bays and beaches in the Winam gulf is covered comprehensively by this plant. As the plant has started to cover large area of the gulf, its impact on community of the gulf specially the riparian community has become enormous. This aquatic weed has been associated with major negative economic and ecological impacts on the Winam gulf as it has disrupted the local economy by impeding fishing activities, transportation, irrigation, water treatment and recreation (Ouma et al. 2005; Williams and Hecky 2005; Twongo 1996). It has also enhanced breeding grounds for vectors of human diseases. (Opande et al. 2004; Mitchell 1990). These negative impacts on ecosystem services have contribute to destabilize the riparian community around the gulf. Efforts to control water hyacinth have recruited a number of strategies including manual removal, mechanical harvesting, and biological control using insects, with mixed results. In particular, the introduction of Neochetina weevils has been credited with significant success in reducing the spread of the water hyacinth (Wilson et al. 2005). This method has been practiced...