## 4 Discussion  
The methodology proposed here, the LUPLES method, uses GIS techniques and the mapping of waterbodies and land uses in their catchment area, as well as the assessment of direct and indirect influences on their hydrology and morphology, to quantify pressures on lentic ecosystems. The method then presents a forecast of its possible ecological status. Figure 8: Relationship between (**a**) morphological pressure level with heliophyte coverage and (**b**) hydrological pressure level with hydrophyte coverage. Pearson coefficient (with the significance of the correlation), as well as linear regression (with the R\({}^{2}\) and significance of the regression model) are shown. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Metric** & **Pressure** & **n** & **Pearson** & \(p\)**-Value** & **Linear Regression** & **R\({}^{2}\)** & **F** & \(p\)**-Value** \\ \hline Emerged macrophytes coverage (\%) & MORP & 47 & \(-\)0.502 & \(<\)0.001 & y = \(-\)0.77\(\times\) + 78.52 & 0.252 & 15.191 & \(<\)0.001 \\ \hline Submerged macrophytes coverage (\%) & HYDR & 38 & \(-\)0.697 & \(<\)0.001 & y = \(-\)1.58x + 70.11 & 0.487 & 33.954 & \(<\)0.001 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Correlations and linear regressions of the macrophytes metrics with the hydro-morphological pressure levels (HYDR: hydrological pressures, MORP: morphological pressures). Figure 7: Relationship between specific pollutants pressure level with (**a**) dissolved oxygen concentration, and (**b**) benthic invertebrate index, as EQR. Spearman coefficient (with Table 2 and significance of the regression model) are shown. In line with the method developed in this study, land uses have been demonstrated to have direct influences on changes in the water quality [54], as well as in the responses of biotic elements [18]. Therefore, as we have demonstrated, they can be used as a proxy to define pressures that are capable of inducing changes in the ecological characteristics of lentic ecosystems. The alterations to hydrological and morphological features, both in the catchment area and the waterbody itself, can also be considered as a source of pressures, as they are capable of modifying the ecological features of the waterbodies [19]. The response of aquatic ecosystems to the defined pressures were reflected in the impacts on the physical, chemical, biological and hydro-morphological indicators, as those established by the WFD guidelines [33]. For pollution-related pressures, the LUPLES method considers the relative influence of each land use according to its relative surface coverage of the whole catchment, and its relative importance for such pressure. The application of this methodology for evaluating land use in the whole catchment and not just in the near-waterbody, is supported by the strong relationship existing between the activities and uses in the entire catchment and water quality [10]. The LUPLES method considers the main implications that different land uses (e.g., irrigated and rain-fed agriculture, livestock, or urban uses) have on eutrophication [44; 45; 46], organic enrichment [47], acidification [48; 49] and pollutants [50; 51; 52]. In the studied sites, the eutrophication pressure level was mainly determined by agricultural land use, with a higher weighting for irrigated agriculture. The weight of agriculture in the global value of the method proposed was decisive considering the implications of agricultural land use in the catchment area on the water quality of the lagoons [44; 45; 46], as this consists of the main source contributing nutrients via runoff [9; 10]. The values obtained from our method were higher in Albufera de Valencia and, to a lesser extent, in Kotychi lagoon; the sites with a higher level of irrigated agriculture relative coverage in their catchment. These two sites, with a very high eutrophication pressure assessment, have been historically altered ([55] for Kotychi lagoon), with a permanent occurrence of cyanobacterial blooms due to nutrient enrichment ([38] for Albufera de Valencia).