## 3 Results and Discussion
### Delimitation of Coastal Lakes
#### 3.4.1 Coastal Lagoons--Louro  
The estimated surface area of the Louro lake is 33.6 ha, distributed across three environmental units: open water, macrophytes (especially need beds, communities of _Phragmites australis_) and herbaceous formations (Figure 3; Table 3). Open water has a total surface area of 19.6 ha, representing 58.2% of the lake. This unit has not suffered substantial changes in the last three decades (Figure 3), although large seasonal oscillations occur. The marked seasonal rainfall, with an important water deficit in summer, leads to \begin{table}
\begin{tabular}{c c c c c} \hline  & & & \multicolumn{2}{c}{**Area Defined by Autonomous**} \\ \cline{3-5}
**Zone** & **Lagoon/Lake Area** & **Free Water Surface** & \multicolumn{2}{c}{**Government**} \\ \cline{3-5}  & **(ha)** & **(ha)** & **Coastal Lagoon** & **Natural Eutrophic** \\  & & & **(ha)** & **Lake (ha)** \\ \hline Louro & 33.6 & 19.6 & 23.3 & - \\ Xüño & 2.3 & 0.005 & 2.3 & 1.7 \\ Vixán & 18.0 & 3.4 & 16.4 & - \\ Bodeira & 1.7 & 0.1 & 1.2 & 0.8 \\ \hline \end{tabular}
\end{table} 
Table 3: Estimated surface in each sector follow our delimitation for the case of the second and third column and employed the surface values included in Annex I of PDRN over the interest zone for this study in the columns defined as “Area defined by autonomous government”. (Source: Xunta de Galicia ©). Figure 3: Coastal lagoon of Louro. (**a,b**) represent the temporal evolution of environmental units in 1989 and 2017, respectively. (**c**) shows Topographic Ruggedness Index (TRI) classification, in black, values below mean and in white the values above mean. (**d**) Official cartography representing the distribution of habitats from Annex I of Habitats Directive. The red line in all cases represent the extent marked for the lagoon by our analysis (IGN [20]; Xunta de Galicia ©). a reduction of 60% in the area occupied by the sheet of water in the end of summer relative to the maximum during the winter [15]. The second unit is a meadow dominated by grass (_Paspalum vaginatum_) and to a lesser extent by _Scripus maritimus_ (association of _Scripetum maritimae_) [34]. This plant formation occurred at the front of the lake and occupied an area of 7.9 ha (23.6%). However, most of this formation was covered by water during periods of maximum water availability (January-April), overlapping seasonally with the open water sector. The reed bed, with presence of _Thypha latifolia_ increased in the peripheral areas, located in the distal and north part of the lake, occupying 14% of the total surface area. In the official PDRN cartography, the zone was divided in three main categories. Some 75.3% of the sector was defined as Coastal lagoon, while 12.8% was fixed coastal dunes and 11.5% was defined as Pseudo-steppe with grasses. In this classification, the habitat distribution was closely related to the distribution of plant units (mainly phytosociological units) and with a low weight of lake system functionality. There was also evidence of internal inconsistences relative to the criteria used for the habitat designation. The main designation error in Louro resides in the inclusion of Pseudo-steppe with grasses and annuals of the _Thero-Brachypodieta_ (habitat 6220), which occupy 12.8% of the surface area in the official cartography; the presence of these plants is very dubious based on the available information and the habitat characteristics. These areas appear at the front of the lake, in an area that is currently dominated by _Paspalum vaginatum_, a non-native species, and to a lesser extent by _Scripus maritimus_, and most of the species associated with habitat 6220 are not present (see [9]). The environmental conditions do not correspond to the ecological requirements of the characteristics plant communities of this habitat. This is defined as a xerophyte Mediterranean grassland dominated by vivacious, annual grass that grows on calcareous substrates with temporal hydromorphism [37]. None of these categories appeared at the front part of Louro lake.