Water Stressors in Europe: New Threats in the Old World

Abstract This chapter deals with human stressorsaffecting aquatic ecosystems in Europe. Section 8.1 briefly reviews the historical evolution of human stressorsand related drivers (particularly land use pressures), notably the decrease in agricultural area, occurring simultaneously with the intensification of agriculture and urbanization, where physical and chemical degradation are extreme. Section 8.2 describes stressorsand regions in which such stressorspredominate. Urbanization is a major pressure in the Central Baltic region, where both inadequately treated urban sewage and wastewater from heavy industriesare numerous and severe. Particularly in the Mediterranean Region, barriers and dams of all sizes are widespread and altered or reduced flows are major stressorsthroughout. The percentage of riparian areas in good condition is only about 25%. Along the Atlantic Coast, poorly treated aquaculture pollutants are common. Section 8.3 shows how stressorsusually act simultaneously, with various possibilities of interactions. A moderate to bad ecological status predominates in water bodies with more than three stressors. Finally, in Section 8.4 , we describe the goals and planning of the Water Framework Directive(WFD) versus the present situation. Approximately one-third of European waters surveyedreach a good to high ecological status, but there has been little improvement in the last years. Riverine water bodies and transitional waters generally have more stressorsand biological impacts, and thus poorer ecological status than lakes, reservoirs, and coastal waters. Central–Baltic rivers generally reveal the worst ecological statuses in Europe, whereas the Baltic Sea and Greater North Sea regions have the worst coastal and transitional waters. Regions with intensive agriculture and high population density are affected by multiple pollutants and have poor ecological statuses, whereas better ecological statuses are reported for floodplains with the remnants of natural areas. Urbanization, floodplain infrastructures, and nutrient pollution(especially nitrogen) are the most important predictors of ecological degradation. The next generations of river basin management plans(RBMP, due in 2021–27) face a huge challenge in reaching the WFD goal of good ecological statuses in all water bodies.