## 1 Introduction  
Wetland ecosystems are essential for biodiversity conservation as they are actively involved in improving water quality and nutrient cycling, and also function as atmospheric CO\({}_{2}\) sinks [1; 2; 3; 4]. In addition, these areas are very fragile and vulnerable to disturbance caused by human activity [5; 6]. Large areas of European wetlands have been lost since the start of the 20 th century and the remainingwetland habitats have been greatly altered [7; 8]. In response to this situation, various different initiatives and international conventions were proposed in the middle of the 20 th century with the aim of promoting the study and protection of these areas (e.g., International Waterfowl and Wetlands Research Bureau (IWRB) and the Ramsar Convention). In 1992, the European Union approved Council Directive 92/43/EEC (referred to here-after as the Habitats Directive) on the conservation of natural habitats and of wild fauna and flora. This Directive established a network of Special Areas of Conservation to protect habitats considered to be of community importance (Annex I lists 233 natural habitats in Europe) and also wild animal and plant species that should be protected (about 900 species, Anne II). These habitats and species formed the basis for the creation of a network of special areas of conservation, called Natura 2000 [9]. The aim of the Natura 2000 network is to ensure the long-term survival of Europe's most valuable and threatened species and habitats, listed in both the Birds Directive (Council Directive 79/409/EEC, 1979) and the Habitats Directive. Member states are obliged to include in the Natura 2000 network all the natural spaces in their territory that include habitats and species that appear in Annex I and II, especially those considered priority spaces. Each Member State is also obliged to maintain and restore, with favorable conservation status, natural habitats, and species of wild fauna and flora of community interest covered in the Habitats Directive [9]. The Natura 2000 network is one of the most ambitious legislative instruments in the field of nature conservation worldwide. However, various problems hamper the effective application of the project. One of the main problems is related to the complexity of some articles (e.g., Art. 6) or ambiguities in the definition of multiple habitats, which has forced the European Commission to elaborate diverse manuals ad hoc, as [10]. Thus, to fully achieve the basic goals established in the Habitats Directive, it is essential to understand the processes and the nature of the components that define each habitat (e.g., drainage network and water composition). This is the only way of correctly designating and delimiting habitats. Much of this information was either not available or was not used when the Natura 2000 network was designed. Delimitation of each habitat is complicated by the method used, as well as by the fact that many protected areas undergo substantial temporal changes in relation to climate conditions and land use by local populations. This obliged the Member States to revise their status within the Natura 2000 network, as established in the Habitats Directive. Galicia has more than 2100 km of coastline [11], and one of the most complex littoral zones in the Iberian Peninsula [12]. Coastal lakes represent one of the most unusual environments in the region. Despite their small size, some coastal wetlands appear among the priority habitats of Annex I and are thus included in the Spanish Natura 2000 network. As it can be difficult to establish boundaries between habitats that appear as a continuum [13; 14], in this study, we carried out a comparative analysis of the delimitation and designation of habitats that appear in the plan developed by the Xunta de Galicia (Government of the Autonomous Community of Galicia) for the implementation of the Natura 2000 network, i.e., the _Plan Director de la Red Natura 2000 de Galicia_ (PDRN) (Decree 37/2014, Xunta de Galicia) for four lakes in the region.