Monetary evaluation of aquaculture ecosystem services

Fishponds are interesting freshwater systems where natural and anthropogenic processes interact, mirroring the biogeochemical cycles found in natural wetlands, and providing a wide range of ecosystem services (ES) such as provisioning, regulating, and cultural services. The investigation of a wide range of services provided by fishponds, both in terms of biophysical and monetary accounting, remains critical to ensure the cost-effective provision of ES.  Therefore, the aim of our study was to carry out a model-based assessment of the ecosystem services (ES) provided by fishpond aquaculture and, furthermore, to perform a monetary valuation of these ecosystem services. The work was carried out in two steps: first, a biophysical process model of the pond food web and associated reed vegetation was developed. The unified elements of Programmable Process Structures (PPS) are used to analyse the underlying processes (physical, chemical, biological, ecological, technological, and managerial) and to determine the effects of management interventions on the environmental interactions of the fishpond agroecosystem. It is also discussed how the calculated quantitative environmental interactions can be used for a more rigorous assessment of ecosystem services (ES). It is concluded that many categories of ES (such as provisioning and regulatory services) can be derived directly from the quantitative environmental interactions. Other categories, such as habitat maintenance for biodiversity and cultural services, can be derived by combining the simulated quantitative data with expert-defined qualitative rules. In the next step, a monetary valuation of these ecosystem services was carried out using various methods such as the replacement cost method, market price method, the application of social cost of carbon, etc., to determine the value in economic terms. The results of this study will be helpful in the development of programmes for the protection and sustainable management of pond aquaculture 
systems.