Boundaries

This ecoregion encompasses the entire Crimea Peninsula off the southwestern coast of Ukraine. It is surrounded by the Black Sea to the west and south, and the Sea of Asov to the east.

Topography

The Crimean Mountains form a range of mountains that parallel the southeastern edge of the Crimea Peninsula. The highest of these is the Main Range, with peaks exceeding 1500 m. More than 130 rivers and streams originate in the Crimean Mountains. These rivers are split into three groups: eastern, western, and southern. The eastern group comprises rivers flowing from the northern slopes of the Crimean Mountains toward the Sea of Azov (into Sivash). This group includes Salgir, the largest Crimean river, and also Kuchuk-Karasu, Biyuk-Karasu, Indol, and Eastern Bulganak. Salgir is formed by the confluence of rivers Angara and Kyzyl-Koba at an altitude of 388 m above sea level, and drains into Sivash in the region of Dzhankoi. The length of the Salgir River is 232 km, and its catchment area is 4000 km². Its upper reaches are mountainous, with a dense network of tributaries flowing from approximately 500 springs. In the lower Salgir, flow does not occur for more than 60 days a year. Waters are diverted for irrigation, and a number of reservoirs have been built in the upper reaches. The lower portion of the Salgir River is now connected with the North Crimea Canal, and thus the river does not flow into the sea.

The western group includes rivers rising from the western part of the Crimean Mountains that flow into the Black Sea. Among these are Chernaya, Belbek, Kacha, Alma, and Zapadnyi Bulganak. The Chernaya River is one of the most abundant rivers in Crimea by volume. Its length is 41 km, and its catchemnt area 436 km². The Chernaya River originates in the mountains where it is fed by numerous springs. At its headwaters its annual water flow is equal to 2.5 m³ sec^-1. The water flow declines further downstream because of irrigation, and near the estuary is only 0.9 m³ sec^-1. In contrast to other rivers of the western group, however, the river does not dry out.

The Belbek is formed by the confluence of two mountain rivers, Uzenbash and Mantotra, flowing from the northwestern slopes of the Main Crimean Range. Its length is 63 km, and its catchment area is 505 km². The river has the largest annual water flow of the Crimean rivers, equal to 3.0 m³ sec^-1. In the steppe part of the flow the waters of the Belbek are diverted for irrigation. From July through September the river usually dries.

Kacha is 69 km in length, and its catchment area is 573 km². The river has considerable slopes (up to 35 degrees in the upper reaches). Some of its tributaries in the mountains have periodic mudflows. Its average annual water flow is equal to 2.1 m³ sec^-1.

Alma is a large river of the western group. Its length is 84 km, and catchment area is 635 km². It runs along mountainous terrain, with a deeply cut valley and high shores. Its slope averages 7 degrees downstream and 21 degrees in the upper reaches. Average annual river flow is 1.3 m³ sec^-1. A number of reservoirs have been built in its channel, including Alminskoe and Bazar-Dzhalganskoye, among others.

The southern group includes rivers of the southern slope of the Main Crimean Range. These are short, steep streams, 8 to 15 km in length, with considerable slopes and waterfalls. The main rivers within this group include Derekoika, Ulu-Uzen, and Uchan-Su, with catchment areas of 40 to 60 km², and mean annual flow intensity between 0.3—0.6 m³ sec^-1.

The steppe part of the Crimea is characterized by a sparse and weakly developed hydrographic network. Surface flow is nearly absent. The river network is represented primarily by dry river channels, only filled with water in spring during the snowmelt and heavy rains. The largest one is the Chatyrlyk, which drains into Kirkinitskii Bay. For irrigation of the steppe Crimea South-Ukrainian and North Crimean canals were built. Their total length is more than 550 km and they are supplied by water from the Dnieper River.

Freshwater habitats

Spring tide is pronounced due to snowmelt in the Crimean Mountains. However, almost all of the rivers within Crimea, particularly in their lower reaches, are subject to drying during dry seasons. At present, the natural regime of the rivers has been greatly disturbed by the construction of numerous dams and reservoirs, as well as for irrigation canals.  The connection between the lower reaches of the rivers and the sea has been disrupted, and as a result has practically exterminated all anadromous species of fishes.

Description of endemic fishes

The ecoregion contains two endemics: Gobio delyamurei and G. kachae. Gobio delyamurei is a native gudgeon that has been found in only moderately fast-flowing and stagnant parts of the Chernaya River in a section only 25 km long. The species is likely to become extinct in the near future due to increased water extraction. Gobio delyamurei is distinguished by a number of morphological chracteristics, and the dusty, dark grey colour of its body and fins.

The Crimean barbel (Barbus tauricus) is a near-endemic with the Western Transcaucasia ecoregion [433]. It is thought to be distributed throughout the entire ecoregion – in rivers and streams of the Black Sea basin (Chernaya, Belbek, Kacha, Alma, Uchan-su) and the Sea of Azov (Salgir with Biyuk-Karasu). It inhabits mountainous streams with a fast current, rapids, and gravel, pebble, or rocky bottom. It inhabits rivers characterized by considerable differences in water level between the dry (summer) and wet (spring floods) seasons. It also prefers river sections between 200-600 m above sea level. It is included in the Red Data Books of Ukraine (Shcherbak 1994), category 3 (rare). However, recent research (Bogutskaya, Freyhof, unpublished) has revealed that there are probably two more distinct species, all local endemics, included in the complex, "Barbus tauricus".

Ecological phenomena

Due to a pronounced spring tide and summer dry period for Crimean rivers, many fish species are not able to complete annual and life cycles. Thus, purely freshwater species are isolated to short sections of rivers in mountain areas because the lower reaches are unfit for habitation. During summer, the lower reaches become salinized with concentrations up to 2000-5000 mg/l, and in the Crimean steppe concentrations during low water levels may reach up to 10,000 mg/l.

Justification for delineation

For ecoregions of the former Soviet Union, a species/genera/family presence/absence matrix was compiled for a hierarchy of hydrographic units, and cluster analysis and ordination techniques (Primer v.6 statistics software) were employed to assess biotic similarities among hydrographic units and to identify major faunal breaks.

This ecoregion, which encompasses the Crimean Peninsula, is distinct due to its historical isolation from adjacent regions because of its unique geomorphology and paleohistory.  

Level of taxonomic exploration

Fair. Most native taxa need further revision to evaluate their status.