L’Albufera lake (2.400 hectares) is one of the most singular water bodies in Spain and is part of a 21.200 hectare Natural Park with a very high environmental value. For this reason, it is included in the RAMSAR List of Wetlands of International Importance; it is a site of Community importance and a Special Protection Area (SPA).
Nevertheless, its water quality is extremely deficient. It is common knowledge that since the last quarter of the XX century it has been in a hypertrophic status. Even though the actions regarding waste water management and treatment developed in the last few years have improved its status, it is still far from complying with the objectives established by the Water Framework Directive (2000/60/EC). This fact can be observed in the trend evolution of chlorophyll-a over the past thirty years.
The main problems in L’Albufera lake still exist and they directly affect a series of habitats and priority species closely related to water quality in the wetland.
The lake’s degradation has gone hand in hand with habitats degradation and, therefore, has sometimes limited the presence of these species, and the evolution of the number of breeding water birds in L’Albufera of Valencia.
As for objectives and birds established in the SPAs specifications, for many species the basic objective for water might be enough to guarantee as well a good status of bird conservation –thus accomplishing the objective of SPA conservation– if this has been defined. Nevertheless, that minimum quantity of water might not be enough to maintain the most sensitive or demanding water bird populations (and the wetlands sheltering them).
The WFD contemplates this possibility and if that is the case in a particular water body, the WFD establishes that the most demanding objective should prevail.
On the other hand, public administrations are obliged to elaborate management plans in the Natura 2000 Network wetlands in the case of protected sites with a habitat or species dependent on water. These plans have not been drafted in most of the cases, according to the report recently developed by SEO/BirdLife. They must include management/conservation objectives particularly defined for each site, and be coherently established in the compliance framework of the Community directives (water, habitats and birds).
To this end, it would be necessary to previously determine an ecological potential –not an easy thing to do– especially in regards to avifauna and based on the compliance of objectives related to the Birds Directive. Therefore, as these objectives are not contemplated in many cases, the few Management Plans developed including these objectives do not consider them jointly for the compliance of all three directives. Instead, they are considered individually, which might result in a conflict for complying with the three directives and, therefore, might not achieve the management objectives with the required coherence for a Natura 2000 Network site.
For over five years, three environmental restoration actions have been carried out in L’Albufera Natural Park, which have resulted in a series of wetlands. A group of old rice fields have been recovered as constructed wetlands, known as:
Artificial Wetlands of Tancat de Milia
Artificial Wetlands of Tancat de l’Illa and
Artificial Wetlands of Tancat de la Pipa
The first two artificial wetland systems present a similar typology: in the water flow order, a first sector as artificial wetland with subsurface flow (Sector A), a second sector as artificial wetland of surface flow with emerging macrophytes (Sector B) and a third sector of lagoon typology (Sector C) as artificial wetland with surface flow and diverse macrophyte vegetation, both emerging and submerged.
The third action is similar but has no Sector A with subsurface flow. In total, the transformed surface has been some 90 hectares.
Although located in L’Albufera lake area and initially conceived to improve water quality in the lake and thus support the compliance of the WFD objectives, these three artificial wetlands have been constructed by different organisations and have even been conceived to improve water quality of different origins. The two promoting organisations of these actions, the Júcar River Basin Authority and the Public Company ACUAMED (Aguas de las Cuencas Mediterráneas, S.A.), focus their efforts in learning if water quality undergoing treatment in the artificial wetlands improved.
Additionally, during the design phase of the artificial wetlands several social and environmental non-governmental organisations were involved. During the construction of the artificial wetlands, this involvement ensured that not only the water treatment parts (sectors A and B) were included, but also a better integration in the environment (sector C).
This enhanced integration has resulted in wider habitat diversity. Together with a better quality of the available water, this has turned the three regenerated sites in key areas within the Natural Park of L’Albufera, so that bird populations that had decreased for years, or even disappeared, can grow and be recovered.
For this reason, these three systems of artificial wetlands revealed themselves as the ideal location to develop this project, as they intend to reproduce –to a small scale– the optimal performance of natural wetlands similar to L’Albufera.
It is now possible to carry out a management that, besides considering the water quality improvement (WFD), integrates and applies the Habitats and Birds Directives in order to achieve the objectives of favourable conservation status that the SPA of L’Albufera must comply with within the framework of the Natura 2000 Network.
The first results obtained are still scarce and only come from “Tancat de la Pipa”, one of the three systems that has been systematically controlled for the past three years. The water treated in this system comes from L’Albufera, so any reduction in the pollutants means a quality improvement in respect of the lake’s water. It has been observed that both water quality and biodiversity have undergone positive changes during this period.
On the other hand, the avifauna follow-up, a key component in the biological wealth of the natural park (also designed as SPA and IBA), has proved that artificial wetlands have allowed to considerably improve the status of water birds populations, which due to their ecological requirements are tied to areas with good water quality and large marshy areas. That is the case of the Netta rufina, which has duplicated its breeding population, Anas strepera, Anas clypeata and Circus aeruginosus. A breeding place that had been empty for the past few decades has been recoverd. Also, other species included in Annex I of the Birds Directive, such as the Fulica cristata and Botaurus stellaris, show a relevant winter presence in these sites, as well as breeding attempts. Marmaronetta angustirrostris shows a relevant presence during the breeding period and Oxyura leucocephala is present during the post-breeding period, an unprecedented fact before the existence of these sites.
This project’s proposal is to prove that an integrating management of the water quality and biodiversity requirements in artificial wetlands has a better result than a management focused only on one of the two points. To this end, by using the three existing wetland systems, different management strategies will be tested to optimise the compliance with the three above-mentioned Directives. It is intended to prove that the joint management of these three renaturalised sites contributes to both water quality and biodiversity improvement in the Natural Park of L’Albufera. The results might be transferred to actions in similar ecosystems, that is, Mediterranean coastal wetlands with a water quality decrease and with the capacity to recover sites in their area as artificial wetlands.