Palaeoecological and documentary records of recent environmental change in Garaet El Ichkeul: A seasonally Saline Lake in NW Tunisia

Abstract

A palaeoecological and documentary study of the RAMSAR site of Garaet el Ichkeul in NW Tunisia demonstrates that the ecology of the lake has undergone significant changes over the last 400–500 years. 210 Pb dating of short sediment cores from the lake shows a significant increase in sediment accumulation rates over the last 150 years. This is associated initially with an increase in agricultural intensity within the catchment by French settlers in the late 1800s. Subsequently, sediment accumulation rates increased further as a result of anthropogenic modifications to the course of the Oued Dioumine. Pollen evidence suggests that Potamogeton, the major food resource of wintering waterfowl, only became established in the lake in c. AD 1890. This establishment appears to be associated with changes to the hydrological regime of the adjoining Lac de Bizerte by construction of the Bizerte Ship canal in AD 1895. The current importance of Ichkeul for wintering waterfowl is probably a direct consequence of these anthropogenic modifications and the dramatic reduction in wetland areas in the Mahgreb over the last 100 years.