Cave

The habitat includes natural caves and cave systems with their associated cave water basins. Caves and their associated waters harbor various biotic communities (plants, animals, fungi and algae) that are restricted to them (troglobiont organisms), or are physiologically and ecologically capable of conducting their entire life cycle inside them (troglophile organisms), or are dependent on them for part of their life cycle (subtroglophile organisms). The habitat is very diverse, but is mainly formed by the karst processes at the calcareous rocks. The caves also vary in size and extent. Their exterior part (cave entrances) includes the twilight zone where light penetrating from the outer world is sufficient to permit human vision. The habitat is rarely vegetated, and in this case dominant plants are mostly algae and mosses, and sometimes also vascular plant species such as  Cortusa matthioli occur. At the interior part of the caves, light is completely lacking. This part is with or without troglobiont or troglophile organisms. The vertebrate fauna includes unique amphibians such as Proteus anguinus in the Adriatic karst systems and bats. Bats are not typical troglobionts because they use the caves only for breeding and wintering. Invertebrate species belong to a limited number of groups, and include remarkable relict species from Gastropoda, Opiliones, Chilopoda (Lithobiidae), Collembola, Coleoptera (Bathysciinae and Trechinae subfamilies) among the terrestrial fauna and Turbellaria, Gastropoda and Urodela, among the aquatic fauna. They form characteristic fauna communities, which are essentially restricted to caves in temperate regions. The majority of the rich in invertebrates’ caves are situated in Southern and South-Eastern Europe (Mediterranean and Balkan Peninsula). The caves may be of different types: dry caves or caves crossed by permanent or temporary watercourses (habitat C6.1),  warm caves and caves humidified by geothermal waters, relatively warm deoxygenated caves, rich in carbon dioxide and sulphur vapor or methane and hydrogen sulphide harboring relict thermophile invertebrate fauna. In the regions with active volcanic activities there are caves formed in lava flows by open-ended tubes or passages resulting from the cooling of the surface (whose molten interior continued to flow). Some large lava tubes on the Canary Islands harbor unique communities of invertebrates, in particular, decapod crustaceans. Caves near the coast, which may contain salt water and can be colonized by specialized (anchihaline) communities, whether or not connected to the sea, are included to the marine habitats.

Indicators of quality:

Caves in good condition are considered the ones that are without any anthropogenic structures and are impacted only by natural processes. These are dynamic systems due to water erosion and collapse of rocks. The main threat is from rehabilitation and lighting for tourist attraction, which would allow non-typical animal and plant species to invade the cave’s interior. Plants growing in caves are equipped with electric lights  known as “lampenflora”. They tend to be less vibrant in color and somewhat disfigured. Typically, lampenflora are mosses, ferns and algae. In caves that are lit constantly by lamps, these invasive plants can cause problems to the cave's natural structure or any prehistoric wall art present. It also may form a threat to troglophile and troglobiont fauna. Indicators of good quality are:

• Stable water regime and annual course of temperature
• Absence of invasive organisms
• No disturbance by humans

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats