Agriculture in arid and semiarid areas involves the management of water scarcity and salinity – salinization. The project focus on the elaboration and interpretation of data collected in the field. The main objectives are to characterize the impact of agricultural activities on microbial communities and determine a set of indicators for assessing the environmental health in such saline/arid environments. Activities will be performed at the Central Ebro Valley (Spain), Gallocanta and Monegros (RAMSAR protected areas under Birds and Habitats Directives) and at the Ichkeul Lake/Bizerte Lagoon (Tunisia) hydrological complex (RAMSAR and UNESCO protected area). The specific objectives of AQUASALT includes to: 1. Determine the seasonal changes of soil/water salinity distribution in two Mediterranean arid areas. 2. Determine the salinity trends in irrigated lands and the agricultural pollutants inputs following the dynamics of nutrients (N, P) and pesticides in range of agricultural saline and gypsum soils around the waters. 3. Characterize the microbial communities dynamics according to agricultural activities and seasonal variations. 4. Establish relevant indicators including microbial and macrofaunal bio-indicators adapted to the natural occurrence of salinity in arid basins. Such bio-indicators would report on the effects of agricultural activities in natural saline areas, useful information for the management of saline wetlands.