High Biodiversity in Hypogean Waters and Its Endangerment – the Situation in Slovenia, the Dinaric Karst, and Europe


Boris Sket


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January 1999


Of approximately 12,600 aquatic animal species, registered in 1978 in Europe, more than 200 were facultative cave dwellers, approximately 1,000 species (in 1998 already 2,000 taxa) or 8%, were specialized stygobionts. More than half are Crustacea. The relatively high number of crustacean hypogean species is rendered possible mainly by (1) the absence of their insect competitors as well as (2) spatial partition due to the small distribution areas of most stygobionts. Slovenia, with approximately 200 taxa in its 20,000 km2, has the highest density, and the Dinaric area with nearly 400 taxa in its only 153,400 km2 has the highest absolute number of stygobiont taxa known in the world. The situation is similar for terrestrial cave faunas. The crustacean diversity is mostly a result of ecological and morphological diversification within a few genera (e.g., Niphargus, Proasellus, Monolistra). However, higher taxa (families, orders) are well represented. Besides some non-specialized newcomers to hypogean habitats, some ubiquitous species (e.g., Asellus aquaticus, Synurella ambulans) possess a number of isolated hypogean populations that are troglomorphic to varying degrees. Hypogean species are endangered by urbanization and other uses of the sensitive karst landscape. Although a slight organic pollution of the energy poor cave waters is favourable to their inhabitants, it may enable invaders from the surface to outcompete troglomorphic specialists in sinking rivers. Conservation of cave species is very demanding, since it requires protection of the whole drainage areas on the surface.


Biology, Carcinology

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Crustaceana, Vol. 72, no. 8 (1999-01-01).