Implication for the use of benthic foraminifera as bio-indicators of pollution: The case study of the Northern coast of Sfax (South eastern Tunisia)

The use of foraminifers as bioindicators of pollution in coastal and paralic environments has undergone a very fast development. Among various criteria, morphological anomalies are sometimes considered as pollution indicators. This paper presents a synthesis of the studies correlating foraminiferal assemblages and environmental concerns. Sediment cores retrieved along the northern coast of Sfax (Tunisia) are used to monitor the response of benthic foraminifera to modern pollution and environmental stress. Sediment samples were separated immediately after collection for benthic foraminifera analysis. Binocular microscope and the Scanning Electron Microscope (SEM) were carried out to identify the most significant, normal or deformed, specimens. All observations confirmed that foraminifera may be used as indicators of pollution after deconvoluting from natural impacts. The most sensitive foraminifera identified in the study area are Ammonia tepida, Ammonia beccarii, Elphidium crispum, Peneroplis pertususles Miliolidae, Peneroplis pertusus et Rosalina sp and Peneroplis planatus. The morphological study of benthic foraminifera from surface sediments attests for the pollution of the actual coast. This pollution is recorded in the benthic foraminifera tests mainly as shell deformations, chambers or streaks or abnormal colors.