Boundaries

This ecoregion lies in the southern Balkan Peninsula, and includes the Vardar (Axios), Aliakmon, and Pineios drainages that drain east of the Dinaric Alps and Pindus Range into the Gulf of Thermaikos and Aegean Sea. It encompasses the countries of the Former Yugoslavian Republic of Macedonia (FYROM) and Greece, as well as a small section in southern Serbia. The ecoregion is bordered by the Southeast Adriatic Drainages [421] to the west, the Dniester-Lower Danube [418] to the north, Thrace [423] to the east, Aegean Drainages [424] to the south, and Ionian Drainages [421] to the southwest.

Topography

The varied topography of this ecoregion includes the plains of Macedonia and Thessaly, valleys, rolling hills, and portions of the Dinaric Alps and Pindus Range in the west, Šar Mountains in the northwest, Osogovske and Maleševske mountains in the east, and Mt. Olympus in the south. The mean elevation of the ecoregion is 660 m asl, but ranges from sea level to 2918 m asl on Mt. Olympus (Nezis 2010). Covered once by the sea, the area contains Triassic-Jurassic limestones and ophiolites (Dermitzakis et al. 1997). The Thessaly plain, a former Pleistocene lake, contains Neogene and Quaternary fluvio-lacustrine deposits (Skoulikidis et al. 2009).

Freshwater habitats

The Axios (in Greece) or Vardar (in FYR Macedonia) drains the second largest catchment in the Balkans after the Evros, including an area occupying more than two-thirds of the FYROM, as well as small portions of Greece and Serbia. It rises near Mt. Korab, and travels roughly 380 km before emptying into the Aegean Sea at the Thermaikos Gulf. It has a mean catchment elevation of 747 m, and a mean annual discharge of 3.62 km³/year. Its main tributaries include the Crna, a right bank tributary, and Brejalinica, its largest left tributary (Skoulikidis et al. 2009). The estuaries of the Axios River are a few kilometers southwest of Thessaloniki, threatening to cut the access to the sea port because of the continuous deposition brought to the Thermaikos Gulf. The river bed has shifted because of technical works (1930-34) in place today. There are 13 dams along the riverbed, of which twelve occur on tributaries in the FYROM (Poulos et. al. 2000).

The Aliakmon is Greece’s longest river. Rising in the eastern Pindus Range it travels 314 km through gentle valleys, narrow gorges, and plains before emptying into the Thermaikos Gulf at an extensive delta shared with the Axios River. The river’s mean catchment elevation is 771 m asl, and its mean annual discharge is 2.7 km³/year. Tributaries include the Pramorítsa, Ventikos, Almopeos, and Edesseos. It also receives the drainage of Lake Kastoria (Skoulikidis et al. 2009). The flow of the river is regulated by an artificial lake that receives water from three hydropower dams.

The Axios delta in the east, the mouth of Loudias and the delta of Aliakmon to the west form a complex and extensive river wetland characterized by high habitat diversity. It includes brackish lagoons, saltmarshes, sandy islets and large areas of mudflats. The site is one of the largest wetland ecosystems of Greece.

The largest natural lake in this basin is Dojran or Doiran (2700 ha), which is a relict eutrophic lake on the border between FYR Macedonia and Greece. It includes fish such as the bitterling (Rhodeus amarus) and spirlin (Alburnoides bipunctatus) (Kottelat & Freyhof 2007).

The Pineios River is located in the southern part of the ecoregion in central Greece. It rises in the Pindus Range and flows 216 km as a meandering river through the Thessaly plain and low mountains before entering the Thermaikos Gulf. Its mean elevation is 431 m asl, and its mean annual discharge is 2.55 km³/year. However, discharge is greatly reduced in the summer due to the intensive use of water resources for irrigation purposes (the Thessaly plain is the largest one in Greece). Water abstraction for irrigation purposes and the intensive use of groundwater have caused over-exploitation problems in aquifers within the Pineios catchment area. Groundwater levels are strongly affected by the seasonal exploitation of water. Some of its largest permanent tributaries include the Titarissios, Sofaditis, and Enipeas (Skoulikidis et al. 2009). Extreme hydrologic events such as floods and droughts are quite common in the catchment.

Terrestrial habitats

This ecoregion can be subdivided into three sub-regions according to WWF (2001) and the Digital Map of European Ecological Regions (DMEER, ETC/NPB 2002). They include the Balkan mixed forests [PA0404] in the north; Pindus Mountains mixed forests [PA1217] in the west; and a sliver of Rhodope montane mixed forests [PA0435] in the east. The Balkan mixed forests occur throughout much of FYR Macedonia, and include such species as Hungarian oak (Quercus frainetto), European beech (Fagus sylvatica), Scots pine (Pinus sylvestris), and silver fir (Abies alba). The Pindus Range mixed forests include species such as European black pine (Pinus nigra) and Greek fir (Abies cephalonica) at higher altitudes and species such as Hungarian oak, downy oak (Q. pubescens), and Turkey oak (Q. cerris) at lower altitudes. Mt Vourinos is a small, isolated but still importantophiolithic region within the ecoregion. There are 20–22 serpentine endemics, among them a high number of local endemics such as Hesperis rechingeri and Viola vourinensis (Stevanovic΄ et al. 2003).

Description of endemic fishes

Around a quarter of the species are endemic to the ecoregion, including the critically endangered Velestino spined loach (Cobitis stephanidisi) and Doiran bleak (Alburnus macedonicus), as well as the Thessaly goby (Knipowitschia thessala, EN), Thessaly gudgeon (Gobio feraeensis, VU), Struma spined loach (Cobitis strumicae), vretenar (Zingel balcanicus), Macedonian trout (Salmo macedonicus), Pelagos trout (S. pelagonicus, VU), and Macedonian barbel (Barbus macedonicus) (Kottelat & Freyhof 2007). Some species, such as the Struma spined loach and near-endemic dark vimba or malamida (Vimba melanops, VU in Greece), stemmed from Danubian lineages (Skoulikidis et al. 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; Economidis 1991; Georgiev 1998). This ecoregion falls within the West Macedonia-Thessaly ichthyofaunal subdivision of the Ponto-Aegean division as defined by Economidis and Banarescu (1991). It includes the drainages between the Vardar and Pineios, and reflects a Danubian faunistic complex that may have resulted from river capture between the Axios and Morova rivers (Skoulikidis et al. 2009). The ecoregion is noted for its endemics and dissimilarity to other Mediterranean ecoregions (M. Kottelat pers. comm. Jan. 16, 2006).