Benthic foraminifera response and geochemical characterization of the coastal environment surrounding the polluted industrial area of Portovesme (South-Western Sardinia, Italy).

To study the benthic foraminifers' response to heavy metal pollution and analyse the geochemical parameters, samples of surface sediments were collected in 2005 and 2006 from a polluted coastal zone shorefront to the industrial complex of Portoscuso-Portovesme (Sulcis, South-Western Sardinia). The samples came from the upper 1-2 cm of the undisturbed sediments in water less than 2m deep, along coastline (about 8.5 km in length) proximal to emerged alluvial plain. The entire examined marine area represents a shallow inner shelf, which is physiographically fairly protected and characterized by low turbulence, but subjected to southwards littoral drift. Geochemical analyses of seawater, sediments and foraminiferal tests correlated to biotic indexes (Dominance, Shannon-Weaver, Simpson, Eveness, Menhinick, Margalef, Equitability, Fisher-alpha, Berger-Parker and Q-mode Cluster Analyses--Ward Method) and provide data on environmental stress. A total of 38 benthic foraminiferal species were identified. Increasing pollution results in low species diversity, low population density and more frequent abnormal specimens. Results from ESEM images allow recognition of a strong infestation on the calcareous foraminiferal tests by microbial communities developed in the polluted environment.