Postojna-Planina Cave System in Slovenia, a Hotspot of Subterranean Biodiversity and a Cradle of Speleobiology

Abstract

The Postojna-Planina Cave System (PPCS) in central Slovenia is a globally exceptional site of subterranean biodiversity, comprised of many interconnected caves with cumulative passage length exceeding 34 km. Two rivers sink into the caves of the PPCS, called the Pivka and Rak, and join underground into Unica River, which emerges to the surface. The studies of fauna of PPCS began in the 19th century with the first scientific descriptions of specialized cave animals in the world, making it “the cradle of speleobiology”. Currently, the species list of PPCS contains 117 troglobiotic animal species belonging to eight phyla, confirming its status as the richest in the world. Of these, 47 species have been scientifically described from the PPCS, and more than 10 await formal taxonomic descriptions. We expect that further sampling, detailed analyses of less studied taxa, and the use of molecular methods may reveal more species. To keep the cave animals’ checklist in PPCS up-to-date, we have supplemented the printed checklist with an online interface. As the revised checklist is a necessary first step for further activities, we discuss the importance of PPCS in terms of future research and conservation.

A literature-based database of the natural heritage, the ecological status and tourism-related impacts in show caves worldwide

“…2b). The most studied show cave is Postojna cave in Slovenia, which is also recognized as the most important global subterranean biodiversity hotspot (Zagmajster et al 2021), followed by two Spanish show caves, i.e. Nerja Cave and Castañar de Ibor Cave, and by Lascaux Cave in France (Fig.…”

Isolation and endemism in the subterranean aquatic snails of the genus Belgrandiella A. J. Wagner, 1928 (Caenogastropoda: Truncatelloidea: Hydrobiidae)

“…Planinska jama is one of the underground habitats with high biodiversity, including the olm Proteus anguinus Laurenti, 1768, endemic species of amphipod Niphargus Schioedte, 1849, isopods Monolistra Gerstaecker, 1856, Asellus aquaticus cavernicolus Racovitza, 1925 andTitanethes albus (C. Koch, 1841), cave shrimp Troglocaris planinensis Birstein, 1948, cave hydrozoan Velkovrhia enigmatica Matjašič & Sket, 1971, and eight (Culver & Sket, 2000 mostly stygophile gastropod species (including terrestrial Zospeum Bourguignat, 1856 and pulmonate aquatic Ancylus fluviatilis O. F. Müller, 1774), whose empty, two to three millimeter-sized shells form dune-like thanatocenoses at some places. According to Sket (1999) in the Planinska jama PPCS 19, and according to Zagmajster et al (2021) nine (in this seven Truncatelloid) aquatic gastropod species were found, and the number of troglobiotic and stygobiotic animal species approaches 120, similarly high number can be found only in Vjetrenica Cave in Bosnia and Herzegovina . Also the material from earlier studies, collected at 14 other localities in Slovenia, Croatia, and Bosnia and Herzegovina (Table 1, Fig.…”

Island and Rensch’s rules do not apply to cave vs. surface populations of Asellus aquaticus

“…One potential problem is that even though cave communities are indeed simpler than surface communities in the typical A. aquaticus habitats, some of the studied caves can be considered harboring diverse communities by subterranean standards. For example, the Postojna-Planina Cave System harbors 50+ aquatic species including predators, and can be considered as a hotspot for subterranean biodiversity (Zagmajster et al, 2021). The Movile Cave, which is one window of access to the Movile aquifer, harbors 20+ aquatic species, also including aquatic predators (Brad et al, 2021).…”