## 3 Results
### Estimation of Pressure Levels in Coastal Lagoons
Although linear regressions were significant, (_p_-values \(<\) 0.05), a small amount of variance was explained in several cases, which could be due to the nature of the data. Each pressure level assigned in the study sites was correlated with all the available values of each metric. Therefore, for each \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Metric** & **Pressure** & **n** & **Spearman** & _p_-Value** & **Linear Regression** & **R\({}^{2}\)** & **F** & _p_-Value** \\ \hline Ammonium & EUTR & 555 & 0.349 & \(<\)0.001 & y = 0.19x + 0.01 & 0.193 & 14.212 & \(<\)0.001 \\ (umol N-NH4\({}^{+}\) L\({}^{-1}\)) & POLL & 555 & 0.345 & \(<\)0.001 & y = 0.18x + 0.01 & 0.189 & 8.959 & 0.003 \\ \hline Dissolved Oxygen & EUTR & 756 & 0.293 & \(<\)0.001 & y = 9.43x + 123.61 & 0.089 & 73.842 & \(<\)0.001 \\ (umol O\({}_{2}\) L\({}^{-1}\)) & ORG & 756 & \(-\)0.309 & \(<\)0.001 & y = \(-\)11.73x + 422.20 & 0.031 & 24.266 & \(<\)0.001 \\  & ACID & 756 & \(-\)0.427 & \(<\)0.001 & y = \(-\)33.16x + 392.91 & 0.144 & 126.851 & \(<\)0.001 \\  & POLL & 756 & 0.231 & \(<\)0.001 & y = 8.06x + 136.93 & 0.054 & 43.271 & \(<\)0.001 \\ \hline Nitrite & EUTR & 702 & 0.196 & \(<\)0.001 & y = 0.03x + 0.02 & 0.013 & 9.515 & 0.002 \\ (umol N-NO\({}_{2}\)-L\({}^{-1}\)) & POLL & 702 & 0.251 & \(<\)0.001 & y = 0.02x + 0.14 & 0.007 & 5.125 & 0.024 \\ \hline Orthophosphate & EUTR & 575 & 0.519 & \(<\)0.001 & y = 0.16x + 0.01 & 0.188 & 22.812 & \(<\)0.001 \\ (umol P-PO\({}_{4}\) L\({}^{-1}\)) & ACID & 575 & \(-\)0.361 & \(<\)0.001 & y = \(-\)10.09x + 5.62 & 0.058 & 32.850 & \(<\)0.001 \\  & POLL & 575 & 0.485 & \(<\)0.001 & y = 0.15x + 0.01 & 0.180 & 18.363 & \(<\)0.001 \\ \hline Silica & EUTR & 240 & 0.408 & \(<\)0.001 & y = 3.41x + 0.01 & 0.408 & 23.621 & \(<\)0.001 \\ (umol Si L\({}^{-1}\)) & ORG & 240 & 0.576 & \(<\)0.001 & y = 7.33x + 0.01 & 0.455 & 66.200 & \(<\)0.001 \\  & ACID & 240 & 0.269 & \(<\)0.001 & y = 23.73x + 13.14 & 0.174 & 49.951 & \(<\)0.001 \\  & POLL & 240 & 0.554 & \(<\)0.001 & y = 3.35x + 0.01 & 0.431 & 40.578 & \(<\)0.001 \\ \hline Total N & ORG & 169 & 0.328 & \(<\)0.001 & y = 20.29x + 0.01 & 0.438 & 57.900 & \(<\)0.001 \\ (umol N L\({}^{-1}\)) & ACID & 169 & 0.345 & \(<\)0.001 & y = 106.94x + 72.86 & 0.059 & 10.202 & 0.002 \\  & POLL & 169 & 0.490 & \(<\)0.001 & y = 7.65x + 0.01 & 0.407 & 2.728 & 0.050 \\ \hline Total P & EUTR & 452 & 0.591 & \(<\)0.001 & y = 0.41x + 0.01 & 0.190 & 27.814 & \(<\)0.001 \\ (umol P L\({}^{-1}\)) & ACID & 452 & \(-\)0.364 & \(<\)0.001 & y = \(-\)27.0x + 13.76 & 0.054 & 25.519 & \(<\)0.001 \\  & POLL & 452 & 0.560 & \(<\)0.001 & y = 0.38x + 0.01 & 0.181 & 22.425 & \(<\)0.001 \\ \hline Chl-a & EUTR & 440 & 0.206 & \(<\)0.001 & y = 0.62x + 0.01 & 0.245 & 106.638 & \(<\)0.001 \\ (ug L\({}^{-1}\)) & ORG & 440 & 0.256 & \(<\)0.001 & y = 1.01x + 0.01 & 0.204 & 40.635 & \(<\)0.001 \\ \hline Benthic inverteb. & EUTR & 13 & \(-\)0.776 & 0.002 & y = \(-\)0.01x + 0.71 & 0.676 & 22.974 & 0.001 \\ (EQR) & ORG & 13 & \(-\)0.783 & 0.002 & y = \(-\)0.04x + 0.95 & 0.685 & 23.942 & \(<\)0.001 \\  & ACID & 13 & \(-\)0.708 & 0.007 & y = \(-\)0.33x + 1.73 & 0.823 & 51.187 & \(<\)0.001 \\  & _POLL_ & 13 & \(-\)0.776 & 0.002 & y = \(-\)0.01x + 0.77 & 0.683 & 23.705 & \(<\)0.001 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Correlation and linear regression of the physical and chemical indicators and biological quality elements with each of the pressure types defined (EUTR: eutrophication, ORG: organic enrichment, ACID: acidification, POLL: presence of toxic pollutants). Only statistically significant correlations and regressions with _p_-value \(<\) 0.05 are reported here. \(n\) = number of corresponding metrics data used for the analysis. x value (pressure level) the results showed a vertical distribution of points through the X-axis corresponding to the individual data for each associated sampling site at different dates, as found in the European and River Basin Authorities databases.