Assessing the relationship between regulating and provisioning services of Lutembe Bay Wetland, Uganda

Abstract

Wetlands are among the most valuable natural resources providing a number of ecosystem services (ES) such as food, raw materials, water supply and space for recreation. Since wetlands provide a variety of ecosystem services including providing food and water, many stakeholders rely on this ecosystem for their livelihoods. This reliance and continued use may lead to a decline in ecosystem services provided by these wetlands. Lutembe Bay wetland in Uganda situated on the shores of Lake Victoria is prone to human pressures and unsustainable use of ecosystem services. This study aimed to assess the relationship between regulatory and provisioning services for better management of Lutembe Bay wetland ecosystem. The study was carried out for a period of three (3) months between December 2015 and February 2016. Questionnaire survey and focus group discussion (FGDs) were used to assess the major provisioning services in 1999 (16 years ago) and at present (2015/2016) using indicators of measurements for ES such as number of wetland users engaged in particular activities and respondent’s perceptions on importance levels of provisioning ES. The results showed that the most important provisioning ES at present (2015/2016) were clay mining, sand mining and fishing while in 1999 before the expansion of developments the major provisioning ES were fishing, cultivation of crops and clay mining. The water purification as an ecosystem service was assessed by analysis of water quality changes through measurements of physico-chemical parameters, nutrients and total suspended solids content in water from Nakaga stream as the inlet and Lutembe Bay as the outlet. Water samples were collected four times a month in the inlet and bay of Lutembe Bay wetland for total suspended solids and nutrients analysis using standard methods. The results showed that the wetland had a 50% retention of total suspended solids. However nutrients concentration were higher in the outlet of the wetland indicating no retention. It was shown that there was no significant difference (p ˃ 0.05) in the mean concentrations of ammonium, nitrite and total nitrogen in the inlet and the outlet. However, there was a significant difference (p ˂ 0.05) in the mean concentrations of nitrate, soluble reactive phosphorus, total phosphorus and total suspended solids in the inlet and outlet. The changes in water quality in relation to changes in the major provisioning ES were used to assess relationships between ecosystem services and it was shown that a positive correlation though not significant (r = 0.103; p ˃ 0.01) was observed between the major provisioning ES and Lutembe Bay Wetland purification function. The results of this study are envisaged to avail new knowledge on the relationships between provisioning and regulatory services.