BIODIVERSITY OF CROATIA

HAB
H. UNDERGROUND HABITATS
Karst geology represents 46% of the land area of Croatia. Approximately
7000 caves and pits are known, however this number
is expected to increase considerably with new discoveries.
Between the largest is Lukina jama – Trojama pit system on the
northern part of the Velebit Mountain with a surveyed depth of
1392 meters. The largest underground system is \ulin ponor –
Medvedica cave system that is more than 16 kilometers long.
The diversified geomorphology, hydrology and climate have resulted
in remarkable range of underground terrestrial, aquatic
and interstitial habitats. Some of them, such as deep, wet sink-
Specific karst phenomenon is the “vrulja” - the spring under the sea
level (photo: SINP)
holes and limestone glades, and certain alluvial deposits, are
home to numerous relict organisms. A high degree of endemism
occurs in animal species in the limestone glades of the Dinarides.
Some 70% of almost 500 recorded terrestrial and aquatic
cave invertebrates are endemic to Croatia. The largest animal
groups with troglobites (terrestrial cave-dwellers) are beetles,
false scorpions, spiders, snails and millipedes. Crustaceans predominate
between stygobites (aquatic cave-dwellers). Other important
groups include sponges, hydrozoa, planarians, snails,
the only known aquatic cave clam (Congeria kuscer)i and the
only aquatic cave vertebrate – the olm (Proteus anguinus).
The cave Vi{ti~ina jama in the karst surrounding the Neretva Delta area
(photo: SINP)
Marine cave Ropa medvjedina (Monk-seal Cave) on the Lastovo island
was in previous times inhabited by the monk-seal (Monachus monachus)
(photo: \. Huber)
Caves and pits are important habitats for many species of bats
whose winter or summer colonies inhabit them, creating rich layers
of guano that is food base for many group of invertebrates.
Bats are among the most significant inhabitants of underground caves
(photo: SINP)
Underground habitats and species are extremely vulnerable and
threatened by external influence. Quarrying and road building,
pollution of ground waters, disturbance of animals by lighting
in caves open for public and overcollecting of underground
fauna by amateurs are among the main causes of threat.
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