Charophytes, indicators for low salinity phases in North African sebkhet

Among water plants of lakes and ponds, the charophytes are useful for palaeolimnology because they provide autochthonous fossils in the form of their calcified fructifications, termed gyrogonites. Particular species of the Characeae are adapted to brackish water and serve as a modern analogue to infer the salinity of salt lake sediments. Here we focus on Lamprothamnium papulosum whose significance in terms of palaeo-salinity is reviewed with particular attention to the ecological requirements for calcification. New data describe the finding of L. papulosum from Holocene sediments at Sebkha Mellala, Algeria. Previous Quaternary records of this species from North Africa (Mauritania, Libya (Fezzan), Sudan, Mali and Morocco) are discussed in terms of their significance for palaeolimnology. The present paper highlights the potential of fossil charophyte gyrogonites as indicators of former low salinity phases in present-day hypersaline environments.