## 4 Discussion
Each waterbody could have large deviations in their historic series of data, sometimes with high intra-annual variation, as naturally occurs in Mediterranean waterbodies. For the BQE macrophytes and benthic invertebrates, with almost no data for the studied lagoons in the European databases, we compiled the EQR values for the waterbodies included in the study from national reports of the River Basin Authorities from Spain and France, where we found a relatively low number of values. Still, significant trends in some of the indicators studied gave insights into the relationship between the pressure levels obtained from land uses in the catchments and the ecological status assessed by the indicators used. Data for the hydrological alterations were retrieved from a Spanish database that collects the volume of the waterbodies and the height of damming for modified waterbodies, and this allowed for the identification of correlations between the hydrological pressures and macrophyte metrics values. The application of the LUPLES methodology demonstrated the validity of using land use map data as proxies for the estimation of pollution impacts and direct alterations on the hydro-morphology, through the estimation of the different pressures affecting waterbodies, as they responded to the impacts requested by the WFD [33]. Specifically, the six main pressure types assessed (autrophication, organic enrichment, acidification, toxic pollutants, hydrological and morphological pressures) correlated with some of the main indicators of ecological status developed for the implementation of the WFD [32]. In addition, the pressure level was reflected in the impacts on the physical-chemical features and BQE of the waterbodies. The methodological approach described here, combined with the use of the available information and GIS techniques, can be a used not only as an effective method to estimate the pressures on lentic waterbodies, but also as a first approach to predict the ecological status of these ecosystems. Despite the fact that ensuring the monitoring of water bodies is mandatory according to the WFD, there are many aquatic ecosystems that do not have monitoring programs, either because they are not declared as waterbodies, or because they are not under the European regulations, due to them being outside of the European Union. Faster and cheaper methods, such as that proposed here, may help to approach the assessment of the pressures as an indirect way to identify their ecological status when monitoring facilities are not available. Currently, there are multiple sources of geographic information, which represent not only a wide basis to generate knowledge, but also to be applied in the monitoring and management of ecosystems. In this work, we worked with Digital Elevation Models (DEM) that are used for the delimitation of watersheds. These three-dimensional raster are now available at high resolution for the whole of the surface of Europe [42]. On the other hand, Corine-Land Cover (CLC) maps are widely used in many studies [23, 54]. These maps--also available for the whole of Europe [29]--are updated, and may even include maps of land use changes (LULUC). GIS software allows for multiple studies to be carried out using this information through its tools. On the other hand, satellite images in viewers such as Google Earth Pro are highly useful for the assessment of morphological pressures. Appliedscience studies, such as our work, and others focused on determining and developing methodologies for use in the management and monitoring of waterbodies [27; 54], can be of great importance and represent advances that improve the quality of assessments and reduce costs. This is especially useful for covering a larger number of lakes and wetlands, not just those declared as waterbodies in accordance with the WFD by the River Basin Authorities.