Sulfidic caves in South-East Albania—a new hotspot of subterranean biodiversity

Caves represent aphotic subterranean environments characterised by the absence of photosynthetic primary production. The discovery of a sulfidic subterranean ecosystem in Movile Cave (Romania), in 1986, followed by similar discoveries made later in other sulfidic caves, showed that significant trophic resources can be produced chemoautotrophically in situ underground. These resources can support exceptionally abundant and diverse subterranean biological communities, including numerous endemic invertebrate species. To date, every sulfidic cave ecosystem explored has emerged as a hotspot of subterranean biodiversity.

Here, we report on two sulfidic hypogenic cave systems recently explored in south-east Albania in the Vromoner and Langarica canyons. These caves were formed through sulfuric acid speleogenesis, as evidenced by the large subterranean deposits of gypsum and sulfur that cover the cave walls. Recent field observations and surveys revealed abundant sulfur-oxidizing biofilms and rich and diverse invertebrate communities inhabiting these caves. Light carbon and nitrogen stable isotope ratios support the hypothesis that subterranean foodwebs are chemoautotrophy-based, relying on in situ carbon fixation. To date, ten endemic arthropod species have been identified here (scorpions, pseudoscorpions, spiders, springtails, centipedes, and beetles). Notably, a massive colonial spiderweb, hosting over 50,000 specimens of Tegenaria domestica (Agelenidae), was found covering the limestone wall in a sulfur cave. Several species of bats have been identified, including a rare species (Myotis bechsteinii), and large maternity colonies were discovered and surveyed. Our primary focus is on the subterranean biodiversity, ecology, and geomicrobiology of these caves.

We are engaging with local stakeholders to foster conservation actions for the protection of these unique sulfidic caves and for the conservation of the biological communities they host. In collaboration with European initiatives “Save the Balkan Rivers” and “The Blue heart of Europe”, we advocate for the inclusion of these canyons and their caves in the regional national parks of Greece and Albania.