Towards a DPSIR driven integration of ecological value, water uses and ecosystem services for estuarine systems

The aim of this paper is to indicate the overall economic efficacy of competing uses of estuarine resources by integrating ecological value, water uses and ecosystem services into the DPSIR conceptual framework as an added value for policy making and management. The complex interactions between the socio-economic system and the ecosystem (as part of the ‘integral system’ as suggested by the second author before) require generic but still ‘tailor made’ techniques to quantify all relevant variables and to provide an integral view of the system’s status. One of the few techniques that can assist in structuring such complex data in an integrative way is the Drivers-Pressures-Status-Impacts-Responses (DPSIR) approach. Support and regulatory services (such as water supply and water quality) are essential to sustain crucial ecosystem processes and functions while the water required for human activities (water demand) is an essential system service. With the help of DPSIR, the main changes in the Mondego Estuary ecosystem (Portugal) were outlined, used as an illustrative example, and causes and effects described. Within the Mondego Estuary region the main water consumers are agriculture, industry, and households. Baseline scenarios predict an increase in water usage by mainly the touristic service sector. Our analysis illustrates that pressures from human population growth and related activities gradually increased over the studied period. Land-use patterns, diversion of freshwater flows, water pollution and morphological interventions directly caused physical, chemical, and biological modification and degradation. This consequently led to negative ecological and socio-economic impacts, such as eutrophication. The scenarios suggest an increased pressure based on an expected 8% annual population growth and an average annual decreased pressure of 5.2% per annum due to the current reduction in agriculture. The results show that understanding the water use-related complex and intricate trade-offs among ecological, social, and economic goals is fundamental in designing and implementing management policies and ecosystems restoration schemes.