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Ecoregion Description

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Species Richness

# of Endemic Species


423: Thrace

Major Habitat Type:

temperate coastal rivers


Brian Coad


Bosnia and Herzegovina; Bulgaria; Greece; Republic of Macedonia; Turkey


This ecoregion spans the junction of Europe and Asia in northwestern Anatolian Turkey, European Turkey, and eastern Greece. The ecoregion is bounded by the Balkan Mountains in the north, Struma River watershed in the west, Aegean Sea and Sea of Marmara to the south, and the Anatolian Plateau to the east. Its neighbors include the Northern Anatolia [430] ecoregion to the east, Western Anatolia [429] to the south, Vardar [422] to the west, and Dniester-Lower Danube [418] to the north.

Drainages flowing into:

Aegean and Black seas, and the Sea of Marmara.

Main rivers or other water bodies:

The main rivers include the Struma, Maritsa, and Metsa river basins on the European side, the Simav (or Kokacay) River basin along with lakes Kus, Uluabat, Iznik and Sapanca on the Asian side.


Extensive plains surround the Sea of Marmara. The upper reaches of rivers rise from major mountain ranges, such as the Balkan, Rila, and Rhodope mountains in the north and west, and Anatolian Plateau in the east. Elevations range from sea level to over 2780 m.


The part of the ecoregion bordering the Aegean, Marmara, and Black seas falls within a Mediterranean climate zone. The climate becomes continental further inland, and alpine in the mountains. Mean annual temperature averages 12 ºC. Minimum temperatures in the coldest month range from -12 ºC  in the Rila Mountains to 6 ºC along the coast. Maximum temperatures in the warmest month range between 13 ºC and 33 ºC.

Freshwater habitats:

Rivers have fairly gentle gradients on the Asian shore. The lower reaches can be marshy.

Terrestrial Habitats:

Low and relatively even land surrounds the Sea of Marmara in contrast to other fringes of the Anatolian Plateau. The landcover includes mixed forest with irrigated and dry farming and tree crops.

Fish Fauna:

The ecoregion comprises about 80 species in 19 families, with a majority of families with marine origins or affinities. The most speciose family is Cyprinidae, followed by Gobiidae, Clupeidae, Cobitidae, and Acipenseridae.

Description of endemic fishes:

There are no endemic genera, and only six endemic species, including Macedonia shad (Alosa macedonica), A. vistonica, Barbatula bureschi, Cobitis puncticulata, C. punctilineata, and Gobio bulgaricus.

Other noteworthy fishes:

Up to six species of sturgeons, now highly endangered, historically used the waters of this basin for reproduction. These include the Russian sturgeon (Acipenser gueldenstaedtii), Fringebarbel sturgeon (A. nudiventris), starlet (A. ruthenus), starry sturgeon (A. stellatus), sturgeon (A. sturio), and beluga (Huso huso).

Other noteworthy aquatic biotic elements:

Some hydrobiid snails are apparently restricted to east Balkan Rivers, and endemic aquatic insects are also documented (Banarescu 1992). Lake Uluabat has a crayfish fishery.

Ecological phenomena:

This basin has an extensive marine coastline. The lower reaches of rivers, and some lakes, have a fauna derived from the sea that is not seen in more inland basins. The sturgeons have been noted above, but several other marine origin families migrate into fresh water for feeding and reproduction.

Evolutionary phenomena:

Despite being separated by the Sea of Marmara, the fauna shows evident affinities across this water barrier with a number of species that just reach into Asia.

Justification for delineation:

The diversity and species composition separates this fauna from those of neighboring basins. Lakes Uluabat and Manyas are Ramsar Sites. Sturgeons, shads, and kilkas, the cyprinodont Aphanius fasciatus, the balitorid Barbatula bureschi, and the cyprinids Barbus cyclolepis and Petroleuciscus borysthenicus are in the Red Data Book.

Level of taxonomic exploration:



Banarescu, P. (1992). "Zoogeography of Fresh Waters" 2 Weisbaden, Germany: AULA - Verlag.

FishBase (2001) "Search FishBase" <>(2001)

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