The fragile ecology in Iraq’s Mesopotamian marshlands endangered and restructured by a sharp increase in salinity

In southern Iraq, the Mesopotamian marshes have suffered for decades from a decrease in freshwater input from both rivers Tigris and Euphrates. The Shatt Al-Arab River and East Hammar marsh in southern Iraq were affected by a salt wedge that advanced from the Arabian Gulf during July and August 2018, causing a rapid and sharp increase in salinity levels. A monthly monitoring program has revealed an invasion of saltwater species from the Gulf accompanied by the disappearance of native species of freshwater. Seven submerged aquatic plant species disappeared. Thus, the number of freshwater phytoplankton species decreases. It was found that the quality and quantity of small zooplankton significantly changed, resulting in the disappearance of many freshwater species, and the number of freshwater mollusks significantly decreased. A marsh was invaded by two species of marine shrimp that were previously unrecorded, and native freshwater fish species were drastically affected. East Hammar’s fragile ecology is rapidly shifting from oligosaline to estuarine, devastating an important environmental resource and endangering a culturally unique setting.