Boundaries

This ecoregion includes coastal drainages along the eastern Adriatic Sea from Trieste, Slovenia to the Neretva basin and Montenegro coast, finishing at the town of Budva, and including some endorheic basins. Countries include Slovenia, Croatia, Bosnia and Herzegovina, and Montenegro. It is bordered to the west by the Adriatic Sea and to the east by the Dinaric Alps. The northern and southern borders are met by the Julian Alps and North Albanian Alps, respectively.

Topography

This coastal ecoregion stretches from the Adriatic Sea up to the External Balkinides and Dinaric Alps, which run in a northwest-southeast direction. The Dinaric Alps, formed by the Alpine orogenisis, comprise a series of ridges, plateaus, and depressions. The substrate is largely composed of secondary and tertiary sedimentary rocks composed of dolomite and limestone stones, and sand and conglomerates (Tvrtković and P. Veen 2006). Prominent peaks include Troglav, Kamešnica, Biokovo, and Dinara (Sinjal ridge). Most notably the area is characterized by karst topography featuring poljes, or closed flat bottomed basins (Skoulikidis et al. 2009). The coastline includes numerous islands such as Krk, Rab, Cres, Lošinj, Pag, Dugi Otok, Ugljan, Pašman, Brač, Hvar, Korčula, Vis, Lastovo, and Mljet.

Freshwater habitats

The ecoregion is mainly characterized by small coastal rivers, numerous siphonic lakes and pools of the underground karst, and small endorheic basins. Small and medium-sized rivers are typical along the eastern Adriatic coast. Most are surface or subsurface streams, although the Zmanja, Krka, Cetina and Neretva are larger. These rivers have a complex network of surface and underground tributary systems (Tvrtković and P. Veen 2006). The Neretva rises in the Zelengora Mountains in Bosnia and Herzegovina, and flows 255 km through bedrock canyons and plains before emptying into the Adriatic Sea at the Neretva Delta in Croatia. This is the largest delta along the Dalmatian coast, and includes small karstic lakes, flood-meadows, wetlands and lagoons (Skoulikidis et al. 2009). The Krka River flows 73 km to the Adriatic Sea from its source at Mt. Dinara. It flows through a deep canyon as well as rapids, underground springs, and numerous waterfalls along the way, the most notable of which are Skradinski Buk and Roški Falls. The Cetina River also rises at Mt. Dinara, and flows 105 km to the Adriatic Sea.

Karst formations with subterranean rivers, karstic springs, lakes, and swallow holes are distinct hydrological features of this ecoregion. For example, the Pivka River flows into the Postojnska Cave, continuing its path underground (Herak 1972). These subterranean habitats harbor unique species such as the olm (Proteus anguinusin) in the Neretva basin and the Ogulin cave sponge (Eunapius subterraneus) in the Ogulin karst area (Skoulikidis et al. 2009).

Terrestrial habitats

Two terrestrial ecoregions stretch across this ecoregion, the Illyrian deciduous forests along the coast and Dinaric Mountains mixed forests along the Dinaric Alps. Both are characterized by a mixed deciduous forest zone below 1200 m asl in the lowlands, valleys, and canyons, and a conifer zone between 1200 and 2500 m asl. Broadleaf species include a variety of oaks (i.e. Quercus frainetto, Q. pubescens, Q. cerris, Q. robur, and Q. petraea), as well as oriental hornbeam (Carpinus orientalis), European chestnut (Castanea sativa), hop hornbeam (Ostrya carpinifolia), European ash (Fraxinus excelsior), and field elm (Ulmus minor). A smaller part, mostly in the narrow Adriatic coastal zone, belongs to the Mediterranean evergreen forests of Holm oak (Quercus ilex) and Aleppo pine (Pinus halepensis). Forest stands are mostly in stages of low woody formations - maqius and garrigues. Dominant canopy trees of the conifer forests include Common spruce (Picea abies), European silver fir (Abies alba), European beech (Fagus sylvatica), and European black pine (Pinus. nigra). The ecoregion contains relatively high floristic endemism with many relict and restricted range plant species such as Degenia velebitica, Primula kitaibeliana, Symphyandra hofmannii, Bupleurum karglii, Viola elegantula, Sibiraea croatica, Edraianthus pumilio, and others (WWF 2001). Other terrestrial habitats include wet meadows on karst poljes, fens, heaths, grasslands, scrub, and alpine and subalpine meadows (Tvrtković and P. Veen 2006).

Description of endemic fishes

The ecoregion contains several endemic genera (Aulopyge, Delminichthys, Phoxinellus, Salmo) and more than 20 endemic species, which represents half of the species in this ecoregion. Except for the salmonids and two gobids: Neretva dwarf goby (Knipowitschia croatica) and Norin goby (Knipowitschia radovici), which are restricted to the lower Neretva drainage, all of the endemics are cyprinids, including species in the genera Chondrostoma, Leuciscus, Ruitilus, Squalius, and Telestes. Among the salminids, two species are important and endangered: softmouth trout (Salmo obtusirostris), with populations in the rivers Neretva, Vrljika and Jadro; and marble trout (Salmo marmoratus), which live in the Neretva River.

The isolation of the endorheic drainages of Dalmatia and unique karst environments have contributed to the high endemism, particularly for species in the genera Aulopyge, Phoxinellus, Delminichthys and Telestes. The genus Aulopyge, for example, is represented by the monotypic species oštrulj (A. huegelii). It is found in karstic streams, entering subterranean waters during the winter or dry periods (Kottelat & Freyhof 2007). Of the endemics, almost all are threatened according to the IUCN Red List (IUCN 2009). The most critically endangered include species such as the Krbava minnow (D. krbavensis), Jadova minnow (D. jadovensis), Popovo minnow (D. ghetaldii), Croatian riffle dace (Leuciscus polylepis), Čikola minnow (P. dalmaticus), and Čikola riffle dace (T. turskyi).

Other noteworthy fishes

Some of the most noteworthy species in the ecoregion are connected with cave habitats, including species like the oštrulj (Aulopyge huegelii), naked minnow (Phoxinellus alepidotus), Čikola minnow (P. dalmaticus), striped pijor (Telestes metohiensis), and Krbava minnow (Delminichthys krbavensis).  Other species such as the European eel (Anguilla Anguilla), Livno nace (Chondrostoma phoxinus), Zarmanja chub (Squalius zrmanjae), and Neretva dwarf goby (Knipowitschia croatica) use cave habitats during migration, winter shelter, or during droughts (Tvrtković and P. Veen 2006).

Ecological phenomena

The ecoregion is home to the anadromous Adriatic sturgeon (Acipenser naccarii), which occurs along the eastern Adriatic Sea coast between the Po (Italy) and Buna (Albania) drainages (Kottelat & Freyhof 2007). It is listed as critically endangered by the IUCN (IUCN 2009).

Justification for delineation

Southern European ecoregions were delineated based on a bottom-up approach employing both published and unpublished field data and expert assessment (Abell et al. 2008; Bianco 1986, 1995; Mrakovcic et al. 1995). This ecoregion falls within the Dalmatian ichtyofaunal subdivision of the West Balkans as defined by Economidis and Banarescu (1991). It contains high endemism, including three endemic genera (M. Kottelat pers. comm. Jan 16, 2006). Most rivers in this ecoregion have few species other than these endemics, and are thus very isolated.