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Ecoregion Description


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Species Richness


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Threats

447: Namak

Major Habitat Type:

xeric freshwaters and endorheic (closed) basins

Author:

Brian Coad

Countries:

Iran

Boundaries:

The ecoregion comprises the endorheic drainage basin of the Namak (= salt) Lake of north-central Iran. It lies south of the Alburz (Elburz) Mountains, east of the Zagros Mountains, west of the Kavir basin, and north of the Kuh-e Karkas. Ecoregions surrounding it include the Caspian Highlands [446] to the north and west, Upper Tigris & Euphrates [442] to the west, Esfahan [449] to the south, and the Kavir & Lut Deserts [448] to the east.

Drainages flowing into:

Endorheic Namak Lake

Main rivers or other water bodies:

Namak Lake is a 1800 km2 salt lake that is primarily dry. A second salt lake is the Howz-e Soltan, which lies in the same depression as the much larger Namak Lake south of Tehran. A small sump near Arak is also included as part of this basin as it is not separated by any major landform.

The Karaj River is the principal river in the west draining the Alborz Mountains south toward the Namak Lake. The 350 km Abhar River and its tributaries drain the land west of Tehran and south of Qazvin. Its headwaters approach those of the Zanjan River, a Caspian Sea tributary. The lower part of this river is known as the Shur and is salty. Other rivers draining the Alborz are much shorter. The Jajrud (Jaj, Jaji, or Jaje River) to the east of Tehran is dammed at Latian (95 million cu m) for the Tehran water supply.

The Namak Lake receives the Qareh Su (Gharechay), which flows north of Qom, and the Qom River from the Zagros Mountains.

Qanats are still a major feature of this basin. Alamouti (1966) records 260 qanats producing 99 million cu m per year on the Varamin Plain, 220 qanats producing 161 million cu m per year on the Karaj Plain, and 600 qanats producing 200 million cu m per year on the Qazvin Plain.

Topography:

This basin is flanked by the Alborz Mountains to the north, with altitudes exceeding 4200 m, and the Zagros Mountains to the west. To the east is the vast expanse of the Kavir basin and to the south such ranges as the Kuh-e Karkas at 3899 m (33°27’N, 51°48’E). These surrounding mountains provide a source of snowmelt that feeds the rivers. The central part of the basin is part of the Iranian Plateau and is relatively flat. The lowest part of this basin is at 765 m and is covered by water in spring, but this generally evaporates by the middle of summer.

Climate:

The climate throughout much of the ecoregion is semi-arid and arid, although it is more moderate in the mountains. Mean annual precipitation, 200 mm, is relatively low due to the Alborz and Zagros mountains, which block the movement of moisture from the north and west. The mean annual temperature is 13.5 ºC, with mean minima averaging -6 ºC and mean maxima averaging 35 ºC.

Freshwater habitats:

Some rivers are salty and support a limited fauna. The terminal salt lakes are fishless.

The proximity of the capital, Tehran, to the rivers of this basin and its rapid growth in population and industry has led to many water diversionary schemes. There are over 40 dams in this area with consequent effects on river regime flows. Siltation from runoff over sparsely vegetated land means some dams need to be dredged. Qanats have served as refuges for fishes but many are now being replaced by pump wells that do not harbor a fish fauna and groundwater recharge.

Terrestrial Habitats:

The area surrounding the salt lakes is semi-desert, mostly rock with some sand. Vegetation cover is sparse. The foothills and wide valleys of the Zagros and Alborz mountains are characterized by forest steppe. Higher areas are snow covered in winter, with some permanent ice fields and alpine vegetation.

Fish Fauna:

The fishes comprise around ten species in three families (Balitoridae, Cyprinidae, and Salmonidae). Of these, nearly a third are endemic. The fauna is a mix of species with Caspian Sea affinities and southern Iranian affinities.

Description of endemic fishes:

There are no endemic genera and three to four taxa require descriptions or re-analysis for validity. Endemic species include Barbus miliaris, Capoeta buhsei, and Paracobitis iranica.

Other noteworthy fishes:

Native populations of trout (Salmo trutta) occur in the basin. Some reservoirs and other water bodies have been stocked with exotics, or exotic species have been introduced accidentally.

Other noteworthy aquatic biotic elements:

Other aquatic biota have been little studied in this region.

Ecological phenomena:

An undescribed tooth-carp (Aphanius sp.) is a relict of the Tethys Sea.

Justification for delineation:

This ecoregion contains a high degree of endemism in a species-poor endorheic basin.

Level of taxonomic exploration:

Fair

References/sources:

Alamouti, A. M. (1966). "Groundwater resources of Iran" Paper presented at the Symposium on Hydrology and Water Resources Development, Ankara, Turkey.

Coad, B. W. (2002). "Freshwater Fishes of Iran" (www.briancoad.com).

The Nature Conservancy World Wildlife Fund
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