Discovering the Secrets of the Fairy Cave

Revealing and protecting the biodiversity of an unexplored cave

The fairy cave in Bosnia and Herzegovina has never been explored, but it is not untouched. It lies within one of the world’s cave biodiversity hotspots, likely to provide habitat to unique and mysterious cave-dwelling animals. The aim of this expedition is to be the first explorers to discover what lurks in the depths of this cave, survey its biodiversity and help avert a conceivably dark fate – their extinction. The timing of this expedition is critical, the surrounding karst field has already been damaged by the operation of one of the country’s largest coal-fired power plants. Now, plans to expand the plant could end up drying up these caves or contaminating its waters, potentially causing the eradication of species that nobody has ever known existed. Surveying this special habitat presents an immensely exciting opportunity from a scientific perspective, but the ultimate goal is to use this data to fight for its protection. To achieve this, we are joining forces with the most committed teams in the region who are the main voice pushing for change.


Project Timeline

June -July 2021

The cave expedition takes place

July 2021 onwards

Survey data and images analysed and used in campaign efforts

The Intervention

In June 2021 we set out on an expedition to survey the biodiversity of an unexplored underwater cave in Bosnia and Herzegovina. The team included expert biospeleologists, cave divers, cave mappers as well as members of the Croatian Institute for Biodiversity (HIB), local activists from the Center for the Environment (CZZS) and some of us at Mossy Earth. There are two main reasons why we planned this expedition. The first relates to addressing knowledge gaps about biodiversity. It is very hard to protect species if we don´t even know they exist and to assist the recovery of endangered species if we don't know their distribution. This part of the world is a hotspot for cave biodiversity and so by surveying an unexplored cave here we may find species that are new to science. The second reason was that this site is threatened by plans to expand a nearby coal-fired power plant and relevant data was urgently needed by local activists to inform their campaign to protect this unique habitat.

The expedition took place over 3 days and can best be described as a frenzy of scientific exploration. We documented the process and some of the preliminary findings in the video above and the team is currently summarising the results into an expedition report.

This was the first time anyone has ever ventured into this uncharted corner of our planet - a feat which wouldn’t have come about were it not for the funding provided by mossy earth members and the hard work of the cave divers from the HIB and the team from CZZS. Their devotion and passion to preserve a national heritage that remains undiscovered have given us this chance to bring to light what’s been left in the dark.

Diving in such remotely inaccessible caves requires extreme caution and great experience. Petra Kovač, one of the professional cave divers on the team, attaching a guiding line to make sure that an exit is possible even under very low visibility.

Learn More About the Context Behind this Project

The mysteries of cave life and why they matter

Cave dwelling species show unusually high levels of endemism which means that they tend to be found only within a very small range. Some species exist only in a single cave. In an age when few can truly pioneer exploration of this kind; where we have the sense that no stone has been left unturned on our planet; cave divers continue to discover new species on a regularly basis! This thrilling opportunity is what drives the teams persistently working to safeguard these national treasures. Although this is part of what makes biospeleology so captivating it also creates a problem for conservation. Since there are many unexplored caves, there are several species which have not yet be identified. If these caves were completely isolated from the world aboveground and from the damage we are creating at the surface level, this might not be a huge problem. However, they are actually very sensitive habitats. The artificial manipulation of a water courses or the contamination of inflowing water for example, can destroy cave habitat in an instant and cause the extinction of species that no human being has yet seen. This is what makes this challenge so important to us and although we are fighting against the tide of the pollution crisis, there is real hope we can rescue these precious cave creatures.

The olm is one of the threatened animals we searched for inside the fairy cave. Although no olm were spotted during the dives, we also collected water samples to be analysed in the lab for the presence of olm DNA. Photo credit: PROTEUS project team

Why this cave?

The fairy cave belongs to the Cerničko polje in Bosnia and Herzegovina. Put simply, a Polje or karst field is a large flat area where the flow of water belowground has formed long networks of caves. This epic geological feature is common in the dinaric arc region of South-eastern Europe and is the only home to species that exist nowhere else on earth. In this part of Bosnia and Herzegovina, at least two threatened species were thought to occur, the olm (Proteus anguinus) and the striped dace (Telestes metohiensis). The olm is a selected species forming part of our ‘Ugly Ones’ programme which celebrates the outcasts of conservation – those who receive little to no attention nor funding, but fully deserving of their right to survive. There is still very little research into the cave biodiversity of Bosnia and Herzegovina and this specific cave had never been explored offering us the chance to uncover new and rare animals on the web of life.

Much of the karst field surrounding the fairy cave has been damaged by the activities of the nearby Gacko thermal power plant and open-pit lignite mine. Currently, plans are in progress to further expand the activities and this is likely to involve changes to the course of a stream that feeds water into the cave. If not enough is done to prevent this, disastrous effects on life in the cave and stream could occur - it could run dry and all the animals who rely on it to survive would be killed in the process.

Telestes metohiensis is a small freshwater fish that used to be abundant in Gacko polle but is currently only known to occur in the small stream that flows from the fairy cave.

The broader context of Coal in Bosnia and Herzegovina

Coal has been the main energy source in Bosnia and Herzegovina for several decades. The industry employs many people in rural areas where poverty is still widespread and recovering from the impacts of the Bosnian war has proven difficult. Unfortunately, the mining and burning of coal is harming human health, the local environment and is increasing the country’s carbon footprint. Even now, plans are underway to expand existing power plants and to build new ones and this shows that there is not enough pressure and political will to be swift about the transition to renewable energy. This is one of the core issues that the dedicated team at the CZZS are addressing. Through targeted campaigns and activism, they are raising awareness about this issue, trying to halt the destruction, and speeding up the inevitable energy transition. Their courage and persistence with their cause are admirable. It has gathered support from local citizens who rally behind them in demanding a cleaner environment and more prosperous future.

In this expedition, we are focusing on the conservation of cave biodiversity, but the project also fits into this broader strategy because the data will help to push back against the expansion of a large coal mine and power plant. We are extremely thankful to those who have contributed and joined us on this journey to make sure the unseen in nature, is not forgotten.

The Gacko powerplant is one of 5 large coal-fired plants in Bosnia and Herzegovina. Its operation has already damaged most of the surrounding underground habitat and expansion plans could wipe out the last intact caves. Photo credit: CZZS.

Curious to learn more?

If the world of cave biology intrigues you and you haven’t yet read our article about cave dwelling animals you should check it out!

If you want to learn more about the backstory of why we think it is important to protect bizarre creatures like the olm you can listen to our podcast episode about Mossy Earth’s “Ugly ones” programme.

Sources & further reading

Peer Reviewed Research Section
  1. Stop dirty energy – the future is renewable - Center for the EnvironmentExternal link
  2. The energy sector in Bosnia and Herzegovina - Bankwatch NetworkExternal link
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the team behind the project

Team Member

Tiago de Zoeten, conservation biologist at Mossy Earth

Team Member

Dušan Jelić, researcher at the Croatian Institute for Biodiversity

Team Member

Majda Ibraković, Energy and climate change coordinator, CZZS

Team Member

Milica Končar, Biodiversity and protected areas, CZZS

Team Member

Ivana Čulić, Energy and climate change, CZZS

Team Member

Duarte de Zoeten, Co-founder, Mossy Earth