Out of the cave

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Bringing cave species into the light (not literally) © CC-BY-SA 3.0

Finding and protecting hidden species: environmental DNA

Amongst cold, dark caves of dripping stalagtites, there is a diverse community of highly-adapted subterranean species. A scientific breakthrough is helping ensure they are monitored and protected in the future.

How do you find physical evidence of a rare species when most of its habitat (the subterranean rivers of limestome cave systems in the Balkans) is inaccessible to humans? The "human fish" is the largest cave animal in the world. Despite this, Proteus anguinus - a blind, entirely-aquatic salamander commonly known as the olm, and endemic to the Dinaric Karst - is incredibly difficult to find.

Just because it is hidden, does not mean underground biodiversity should be forgotten. Olm is listed as Vulnerable on the IUCN Red List and an indicator of water quality. The rare black olm, a distinct morph (and possibly even a separate species), is known to be restricted to a habitat of less than 30 square kilometres  in South East Slovenia - a single pollution event or badly-planned quarry could wipe it out.

“Not only would we lose such an extraordinary and unique animal, but the people of the region would lose their only source of drinking water in the same moment.” - Gregor Aljančič

Largest cave animal, the olm © Gregor Aljančič



Where: CEPF-funded work in cave systems of Bosnia & Herzegovina, Montenegro, Albania

Project partner: Tular Cave Laboratory, Društvo za jamsko biologijo (Society for Cave Biology, SCB)

Key species: "The Human Fish" Olm Proteus anguinus (Vulnerable)



Critical facts

›  Olm is a threatened species, evolutionary distinct and highly endemic to the region.

›  The Dinaric Karst is the largest continuous karstland in Europe, a global hotspot of subterranean biodiversity.

›  Cave species can be restricted to specific cave systems, and are hard to monitor by traditional means (trapping, visual observation) because of their inaccessibility.

›  Groundwater extraction, river damming, and agriculture all pose new threats to species living in limestone karst systems.

›  Species with little distribution data are not well protectedby official legislations and the impact of new threats cannotbe predicted.

›  If the species can be detected, they can be protected.

›  Olm has even become a flagship species for subterranean fauna, and has helped draw attention to karst ecosystem services and their value for human health.

›  The public have also been involved in ‘olm rescues’, when they find them washed out of caves into the fields after floods.


Discovering the presence of hard-to-reach creatures:

environmental DNA (eDNA) sampling

SCB’s project was the first time eDNA sampling was used successfully to detect a subterranean organism, which they did from easy-to-reach outflows of underground rivers.



Understanding Distribution

›  eDNA techniques were used to find the first physical evidence of olm in Montenegro.

›  Number of known olm localities in Trebižat River & Hutovo Blato priority Key Biodiversity Area (KBA) doubled.



› Understanding its distribution has provided a strong argument for the full enforcement of legal protection for olm in Bosnia & Herzegovina, and to help guide management.

› Evidence has been provided for appealing and advising the nature conservation authorities in Montenegro to start all necessary practical actions to protect olm.

› This work has influenced the protection of three KBAs through proposals for EU Natura 2000 sites.

› Once the authorities are willing, eDNA sampling could form a basis for future monitoring schemes, from Bosnia & Herzegovina to Montenegro and Albania.




"These techniques have brought charismatic subterranean species into the light of public fame, and engaged support to protect them from future threats"

Gregor & Magdalena Aljančič, Tular Cave Laboratory, SCB




Gregor Aljančič | gregor.aljancic@guest.arnes.si






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The Critical Ecosystem Partnership Fund (CEPF) is a joint initiative of l’Agence Française de Développement (AFD), Conservation International (CI), the European Union, the Global Environment Facility (GEF), the Government of Japan, the John D. and Catherine T. MacArthur Foundation, and the World Bank. Additional support in the Mediterranean Basin is provided by the MAVA Foundation. More information on CEPF can be found at www.cepf.net

A fundamental goal is to ensure civil society is engaged in biodiversity conservation.



CEPF is more than just a funding provider

A dedicated Regional Implementation Team (RIT) (expert officers on the ground) guides funding to the most important areas and to even the smallest of organisations, helps build civil society in the region, and shares learned lessons and best practices. In the Mediterranean Basin Biodiversity Hotspot, the RIT is entrusted to BirdLife International, including its Middle East office and the BirdLife Partners DOPPS/BirdLife Slovenia and LPO/BirdLife France.