Tigris-Euphrates alluvial salt marsh

Category: Inland Aquatic Biomes.

Geographic Location: Middle East.

Summary: This unique marshland, with many dramatic seasonal features, is home to many endemic species, a crucial fish nursery, and a vital migratory bird area—and is still struggling to recover from extreme anthropogenic damage.

The Tigris-Euphrates alluvial salt marsh, known as Ahwar in Arabic, is located in the southern reaches of the Fertile Crescent of Mesopotamia, or current day Iraq. The marshes begin where these two major rivers meet to the north of Basrah, the second largest city in Iraq, and drain into the northwest Persian Gulf via the Shatt al-Arab estuary. As of 1970, the marshes were estimated to cover approximately 12,427 square miles (20,000 square kilometers) in southern Iraq and the province of Arabistan in western Iran.

This saltmarsh biome stretches across a complex system of marshes and lakes, connected by waterways and canals that provide habitat for a wide variety of fish and wildfowl, and shelter nursery grounds for commercially important marine fishes and shrimp. This system of marshes can be divided into three main sections: the southern Al Hammar Marshes, the Central Marshes, and the northeastern Al Hawizeh Marshes.

What follows are descriptions of the marshes prior to the destruction and diversion of the marsh waters in 1991. From 1991 to 2003, the marshes lost more than 70 percent of their integrity. Since 2003, the natural flow has been restored and further restoration efforts are currently underway.

Al Hammar Marshes

The Al Hammar Marshes are situated to the south of the Euphrates, extending from the southern Iraqi town of Al Nasiriyah in the west, to the area north of Basrah on the Shatt al-Arab in the east. The Al Hammar Marshes are bordered to the south by a sand dune belt of the Southern Desert. Estimates of this marsh area range from 1,739 square miles (2,800 square kilometers) of contiguous permanent marsh and lake, to a total area of over 2,796 square miles (4,500 square kilometers) during periods of seasonal inundation.

Al Hammar Lake, which dominates these marshes, is the largest water body in the lower Euphrates. It is approximately 75 miles (120 kilometers) long and 16 miles (25 kilometers) wide. The lake is brackish because of its proximity to the Persian Gulf, as well as eutrophic and shallow. The maximum depth of Al Hammar Lake is just 5 feet (1.8 meters) on average, and about 9 feet (3 meters) at high tide.

The Al Hammar Marsh complex has one of the most important waterfowl areas in the Middle East, both in terms of numbers and species diversity. The vast and dense reed beds provide ideal habitat for breeding populations, while the ecotonal mudflats support shorebird feeding grounds.

Central Marshes

The Central Marshes are at the heart of the Mesopotamian wetlands ecosystem, bounded by the Tigris River to the east and the Euphrates River in the south. This section of the marsh system receives water from Tigris tributaries, as well as the Euphrates along its southern limit. The Central Marshes cover an area of about 1,150 square miles (3,000 square kilometers); during flood periods, this may expand to over 2,485 square miles (4,000 square kilometers).

This freshwater marsh complex is densely covered in tall reed beds interspersed with several large lakes. Along the marshes’ northern fringes, dense networks of tributary deltas are the site of extensive rice cultivation. The Central Marshes are considered to be a highly important breeding, staging, and wintering area for large populations of waterfowl species. Endemic (found only here) sub-species of the smooth-coated otter have been reported in the Central Marshes region.

Al Hawizeh Marshes

The Al Hawizeh Marshes are to the east of the Tigris River, straddling the Iran–Iraq border. The Iranian section of the marshes is known as Hawr Al Azim. In the west, they are largely fed by two main tributaries of the Tigris River. During spring flooding, the Tigris may directly overflow into the marshes. Another important influx comes from the Karkheh River in the east.

Extending for about 49 miles (80 kilometers) from north to south and 18 miles (30 kilometers) from east to west, the marshes cover an approximate area of at least 1,150 square miles (3,000 square kilometers). During periods of inundation, the area expands to over 3,106 square miles (5,000 square kilometers). The northern and central parts of the marshes are permanent, but toward the lower southern sections they become increasingly seasonal.

Flora and Fauna

Natural wetland vegetation typically covers the bulk of the marshes. Common reed (Pharagmites communis) dominates the core of the permanent marshes, gradually yielding to reed mace (Typha augustata) in the ephemeral seasonal zone. Deeper, permanent lakes support rich submerged aquatic vegetation typified by species such as hornwort (Ceratophyllum demersum), eelgrass (Vallisneria spp.), and pondweed (Potamogeton lucens).

The Mesopotamian marshes are located on the inter-continental flyway of migratory birds, and constitute a key wintering and staging area for waterfowl traveling between breeding grounds in western Siberia to wintering quarters in the Caspian region, Middle East, and northeast Africa. Known as the West Siberian-Caspian-Nile Flyway, it represents a major waterfowl migratory route in western Asia. Two-thirds of west Asia’s wintering wildfowl, estimated at several million, are believed to reside in the marshes of Al Hammar and Al Hawizeh.

Particularly dependent on the marshlands are the Dalmatian pelican, pygmy cormorant, marbled teal, and an endemic subspecies of the little grebe (Tachybaptus ruficollis iraquensis). The goliath heron, sacred ibis, and African darter, whose world population has been steadily falling, are also known to breed in the marshes.

Furthermore, the marshes have been singled out as one of the 11 non-marine wetland areas in the world with Endemic Bird Area status. The marshes support almost the entire global population of two species, the Basrah reed warbler and Iraq babbler.

The marshes support a rich variety of fish species. Many of the fish are of economic and scientific importance. It is estimated that 60 percent of Iraq’s inland fish catch is caught in the marshes. Fish from the carp family Cyprinidae are dominant in the marshlands. They are of special scientific interest because of their importance in the study of evolution. At least one barbel species, the gunther (Barbus sharpeyi), known locally as bunni, is endemic to the marshands and is of high commercial value.

A number of species are known to spawn mainly in the marshes: the endemic giant catfish (Silurus glanis and S. triostegus); the Hilsa shad (Tenualosa ilisha); and a pomphret (Pampus argenteus). A wide range of marine fishes migrate upstream via the Shatt al-Arab. Of major commercial importance is the seasonal migration of penaeid shrimp (Metapenaeus affinis) between the Persian Gulf and nursery grounds in the marshlands.

Indigenous Population

The Mesopotamian marshlands are considered home to the Ma’adan, or Marsh Arabs, who have occupied this region for the past 5,000 years, and are descendants of the ancient Sumerians and Babylonians. From study of early settlement of the Tigris-Euphrates basin, there is evidence of water management projects dating back over six millennia. Throughout this period, the power base has consistently been constructed on the wealth generated by irrigated agriculture. Following the early civilization at Ur, and later after the rise of the Ottoman Empire, lack of proper land management led to the degradation of arable lands and encroachment of the western desert onto the Mesopotamian agricultural fields.

It was only in the late 19th and early 20th centuries that major irrigation development began to appear once more in the lower part of the Tigris-Euphrates watershed. During this whole period, the system of water management in place was one that attempted to minimize the risks to crop growth. Another characteristic feature of this era was that only a small proportion of the total water in the river was being utilized for human activity. The vast majority of the water flowed unused into the Persian Gulf.

Threats

The entire area suffers from desertification and poor soils. From the 1970s to 2003, Saddam Hussein’s government initiated projects that drained various marshes and streams, reducing or eliminating the marshlands. At one point, they were reduced to less than 10 percent of their former size. By the late-2010s, the marshes had rebounded significantly, but the damage done still left their future uncertain. In 2016, they were included as part of a World Heritage Site by the United Nations Educational, Scientific and Cultural Organization (UNESCO). The site, called the Ahwar of Southern Iraq, encompasses four marshlands in southern Iraq and several archeological sites from ancient Mesopotamia.

While many other regions are studying the potential impacts of climate change, the governments in this area have been slow to acknowledge and respond to the threats. Many governments, already overwhelmed by political turmoil and humanitarian crises, have put climate change studies low on their list of priorities. Nevertheless, in an area where potable water and food sources are critical, any changes to the climate may have a devastating impact on the region, increasing the frequency of droughts, creating food shortages, and reversing efforts to help bring the Tigris-Euphrates Salt Marsh biome back to full recovery.

Bibliography

“The Ahwar of Southern Iraq: Refuge of Biodiversity and the Relict Landscape of the Mesopotamian Cities.” United Nations Educational, Scientific and Cultural Organization, 2022, whc.unesco.org/en/list/1481/. Accessed 30 Aug. 2022.

BBC News. “Iraq’s Marshes in Doubt.” August 30, 2006. http://news.bbc.co.uk/2/hi/science/nature/5295044.stm.

Hussain, Najah A., et al. “Structure and Ecological Indices of Fish Assemblages in the Recently Restored Al-Hammare Marsh, Southern Iraq.” BioRisk 3 (2009).

McNab, Christine, et al. United Nations Integrated Water Task Force for Iraq. Managing Change in the Marshlands: Iraq’s Critical Challenge. New York: United Nations Integrated Water Task Force for Iraq, 2011.