Benthic foraminiferal assemblages from three polluted areas in Southern Sardinia (Italy): A review

Previous studies evidence that benthic foraminifera are excellent indicators for monitoring the marine-coastal environments (e.g. Armynot du Châtelet et al., 2004; Coccioni, 2000; Debenay et al., 2000; Geslin et al., 2000, 2002; Murray, 2006; Samir & El-Din, 2001; Scott et al., 2005; Yanko et al., 1994, 1998, 1999; etc.). A detailed study on shallow-water benthic foraminifera of three polluted areas in Sardinia (Portoscuso-Portovesme, Santa Gilla Lagoon and Cagliari Gulf) were carried out in order to get informations on the environmental quality of these areas. Studies of marine sediments collected in Portoscuso-Portovesme (South-west Sardinia) revealed high concentrations of Hg, Cd, Pb and Zn (Cherchi et al., 2009), whereas Santa Gilla lagoon near Cagliari, is particularly affected by a high trace element content, mainly Cr, Cu, Hg, Ni, Pb and Zn. Mercury shows values up to 10 times higher than the background level (Frontalini et al., 2009). On the basis of a preliminary study (work in progress), the spatial distribution of the foraminiferal assemblages and the geochemical data reveal from highly to less heavy metals polluted conditions in the western part of the Cagliari Gulf (industrial area). Biological data and heavy metals contents were analyzed both with bivariate (correlation matrix), multivariate techniques of principal component analysis (PCA) and cluster analysis. The benthic foraminiferal assemblages react to increasing concentrations in heavy metals, often considered as very harmful for the environment. In the studied areas, the statistical analysis shows a possible control of the pollutants both on the taxonomic composition of the benthic foraminiferal assemblages and the development of test abnormalities. The discovery of a very depauperate foraminiferal assemblage and the occurrence of abnormalities, particularly emphasized in the innermost part of the Santa Gilla Lagoon, in Portovesme stations near the industrial complex, and in the western part of the Cagliari Gulf, testify important stress conditions in these areas. Ammonia tepida, Haynesina germanica and bolivinids show tolerance to environmental disturbance and pollution, these species are therefore particularly suitable as bio-indicators in coastal areas.