The conservation of prehistoric caves in Cantabria, Spain

The Nerja Cave is developed within dolomitic marbles belonging to Sierra Almijara, some four kilometres East of Nerja in the province of Malaga (Spain). The cave, with a nearly horizontal development, has a total surface of 35,000 m2. It was discovered in 1959 and open to visits one year later. With about 450,000 visitors per year, the Nerja Cave represents a very important natural and cultural resource for the tourism industry of the region where it is located. The important archaeological site of the cavity motivated its declaration as Good of Cultural Interest with the category of Archaeological Zone. In addition, Nerja Cave is internationally recognized as Heritage Sight of Geological Relevance. Moreover, animal endemism and singular speleothems raise the Nerja Cave as highlight of the Natural Heritage of Andalusia. Since it was discovered, many research projects have been carried out in the cave, on geology, hydrogeology, microclimate and microbiota, among others. The results allowed the identification of natural or anthropogenic elements which can be a risk for the conservation of the cultural and natural heritage of the Nerja Cave and also the design and application of the most appropriate preservation protocols. Among these, delimitation of the protection area, assessment of the anthropogenic impact in the cave and the gradual replacement of unsuitable materials previously used in the tourist track. Additionally, specific protocols are being developed to reduce the photosynthetic biofilms which cause biodeterioration and/or aesthetic damage to surfaces.