Boundaries

The ecoregion comprises an endorheic drainage basin of the Zayandeh River in central Iran. It is bounded by the Zagros Mountains on three sides, and drains to the Gavkhuni swamp. It is bordered by the Namak Lake basin to the north, Tigris-Euphrates basin to the west, and Kavir and Lut deserts to the east and south.

Topography

The western areas of this basin are part of the Zagros Mountains, with elevations exceeding 3800 m. In contrast, the lowest elevations around the terminal sump are less than 1450 m.

Freshwater habitats

The Zayandeh is dependent on snow melt in the Zagros Mountains. It flows through the large oasis city of Esfahan, but does not reach its terminal basin for much of the year. There is a heavy demand for water resources for agriculture, industry, and municipal water supplies. Pollution is an important factor in this basin affecting the natural fauna. In addition, dams affect the flow regime and probably harbor exotic fish species.

Batlaq-e Gavkhuni is a salt marsh with an average depth of one meter. Both it and the marshes of the lower Zayandeh River experience wide seasonal flood fluctuations, with flooded areas freezing in winter and drying up in late spring or early summer. Marshes at the river delta and along its banks range from fresh to brackish, and contain little natural marsh vegetation.

Terrestrial habitats

Much of the surrounding land in the lower parts of this basin is semi-desert. Irrigated areas support farming, but agricultural practices have resulted in pollution. Mixed forest in the western mountains grades through steppe to semi-desert.

Description of endemic fishes

There are no known endemics, but two Cyprinidae are probably new taxa, and a new species of tooth-carp (Cyprinodontidae) is in press.

Justification for delineation

This ecoregion encompasses an oasis basin with a limited fauna and probably a higher degree of endemism than currently known. Wetlands associated with the terminal sump are listed as a Ramsar site and are important for waterfowl.

Level of taxonomic exploration

Poor