Sustainability and the value of the ‘regulating’ services: Wetlands and water quality in Lake Victoria

The regulating services provided by ecosystems are amongst the most important for the sustainability of resource use, and yet they are also amongst the least understood. This paper considers one set of regulating mechanisms – the buffering functions of wetlands – and considers the information needed to identify both the value of the services offered by wetlands, and their substitutes. Using data from a catchment discharging water and nutrients to the Kenyan segment of Lake Victoria, the Yala catchment, the paper models the interactions between agriculture and fisheries as mediated by wetlands at the lake margin. More particularly, it estimates the value of the forgone nutrient retention function involved in the conversion of the wetland to agriculture, and the scope for providing the same services through land use change elsewhere in the catchment. The total cost of the payments that would compensate farmers for on-farm nutrient buffering services is 3.86 M US$ year− 1, or 35% of the total gains from wetland conversion to crop production. This finding contributes to an understanding of both the value of regulating services and how they might most effectively be delivered in alternative ways.