Protection category:  natural monument

Year of protection:  2024

County:  Karlovac

Location description:  the Mrežnica-Tounjčica river basin, which includes the upper course of the Mrežnica river and the lower course of the Tounjčica river in the areas of the cities of Ogulin and Slunj and the municipalities of Tounj and Barilović

Area of ​​protected area: 671.67 ha

Natura 2000 area: HR2000593 Mrežnica – Tounjčica

Basic features:

The fundamental natural value of the natural monument area is represented by the preserved karst watercourses of the Mrežnica and Tounjčica rivers. Mrežnica is a karst river with more than 90 travertine waterfalls in different stages of formation, and the river Tounjčica is the largest tributary of Mrežnica, which springs from a cave about three hundred meters deep near the village of Tounj. In the area of ​​the Natural Monument, 63 travertine barriers have been recorded, of which 30 natural travertine barriers are in the process of succession.

The Mrežnica River basin is characterized by very interesting geological features and a rich geological heritage. Part of the area belongs to the most complex area of ​​the karst part of the Dinarides, which is tectonically very complex with characteristic scaly structures and dominant young-fault, or block tectonics. The expected result of the karstification process on this carbonate substrate is the appearance of numerous underground morphological forms: caves, pits and abysses.

In the upper reaches of the Mrežnica and Tounjčica rivers, canyon elements of the landscape stand out, and in addition to watercourses and travertine barriers, the area downstream from the confluence of the Tounjčica and Mrežnica rivers also stands out for its compact forest areas, covered mainly with sessile oak and common hornbeam forests, as well as beech forests. 

Interesting facts:

The upper and source parts of the Mrežnica and Tounjčica watercourses are of particular importance for the strictly protected and target species of crayfish ( Austropotamobius torrentium ). In addition to the crayfish, this area is also home to the river or noble crayfish ( Astacus astacus ), which is also a strictly protected species, and the narrow-nosed crayfish ( Astacus leptodactylus ).

The rapid parts of the Mrežnica and Tounjčica streams are also important for the target species of fish: barbels, roaches, roaches and large porpoises. Out of a total of 45 species of freshwater fish recorded in this area, 8 of them are strictly protected, and a total of 6 species are considered endemic to the Danube basin: the Danube flounder ( Eudontomyzon vladykovi ), the Danube flounder ( Gobio obtusirostris ), the thin-tailed flounder ( Gobio uranoscopus ), the white-finned flounder ( Romanogobio vladykovi ), the large flounder ( Romanogobio vladykovi ) and the roach ( Ritulus virgo ).

Of the strictly protected species, the target species creeping celery ( Apium repens ) has also been recorded in the area of ​​the natural monument . Creeping celery is a rare plant species recorded in a small number of locations in Croatia, and grows in wet and aquatic habitats such as wet meadows, ditches and shallow ponds, and river backwaters.