Metals anomalies in foraminiferal shells as indicators for industrial pollution: a case study from the Mediterranean coast of Tunisia

Abstract

In recent years we have been witnessing a considerable growth of industrial facilities along coastal areas. Some of these have major economical and national importance yet their operation can introduce a wide range of chemicals that might contaminate the coastal area and impact local ecosystems and our health. Among some of these harmful chemicals are metals that are introduced to the coastal environment by some of these facilities. Here we present a novel approach for monitoring low-level industrial pollution in coastal environments based on anomalies in metal concentration within foraminiferal shells. The comparative study between the faunal content and the heavy metalsenrichments in each sample displayed positive character indicating the worsening of the environmental conditions.Sediment cores retrieved along the northern coast of Sfax (Southeastern Tunisia) are used to monitor the response of benthic foraminifera to modern pollution and environmental stress.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, 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