Occurrence and distribution of the foraminifer Ammonia beccarii tepida (Cushman) in water bodies, Recent and Quaternary, of the Dead Sea rift, Israel

The euryhaline foraminifer Ammonia beccarii tepida has lived in water bodies of the Dead Sea rift from at least 2.0 Ma to the present day. It was found in the Mazar Formation, the Samra Formation, the 'Ubeidiya Formation, and the 30-year old Navit Pool near Mount Sedom. The lakes in which these formations were deposited are athalassic (i.e. not marine relicts), and are mutually unconnected in time and space. Their Ammonia faunas were not inherited, but a result of repeated colonization (most probably by avian transport). Ammonia beccarii tepida, though hardy and opportunistic, flourishes mainly in shallow, saline to brackish environments. Its fossil distribution in the Dead Sea rift shows that in mature lakes it tends to disappear, either due to competition from non-foraminiferids, or due to excessive freshening of the aqueous environment.