LIVING AMMONIA FROM A HYPERSALINE INLAND POOL, DEAD-SEA AREA, ISRAEL

A monospecific living population of the foraminifer Ammonia beccarii (Linne) tepida (Cushman, 1926) was found in Navit-3, a small, 25 year old, hypersaline pool. The pool is situated in the Dead Sea rift valley near Mt. Sedom (southern Israel), more than 100 km away from the nearest marine coast. The salinity of the water ranges from 39.7 parts per thousand in winter to 54.5 parts per thousand in late summer; water temperature ranges from 21-degrees-C in winter to 35-degrees-C in summer. The foraminifers live mainly in microbial mats on the shallow-bottom parts of the pool. Surface and core-sediment samples contain A. beccarii tepida thanatocoenoses which reflect the living population. The appearance of the foraminifers towards the upper part of the core is related to the recent formation of the pool and its colonization by means of migrating birds. The microfaunal monospecificity is due to the remoteness of the pool from the sea and to the ability of this subspecies to withstand stress conditions. High rates of abnormal tests observed in the population are related to seasonal stress conditions and the ionic composition of the water.