The bivalve Ruditapes decussatus: A biomonitor of trace elements pollution in Sardinian coastal lagoons (Italy)

The anthropogenic contamination of water bodies with metals via fertilizer, industrial sewage and urban wastewater has resulted in widespread problems in aquatic organisms, but also poses a risk to consumer health. Shellfish from coastal and estuarine environments bioaccumulate toxic metals in their tissues due to their ability to concentrate inorganic contaminants several orders of magnitude above ambient levels. The aim of this study was to evaluate the presence of trace elements in adult specimens of indigenous clams (Ruditapes decussatus). To this end, wild clams were collected from four different brackish areas of Sardinia (Western Mediterranean Sea, Italy) devoted to extensive aquacultural practices. The concentration of 16 trace elements (Al, Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, Sn, Tl and Zn) in the tissues of the clams was quantified. The legal limits set by European Regulations for cadmium; mercury and lead were never exceeded. However, unexpectedly high values for aluminium and iron (mean 207 mg kg⁻1 and 113 mg kg⁻1 wet weight) were found in Santa Gilla lagoon, which is close to industrial settlements and had the highest values for the majority of chemical elements investigated. The highest values of the metalloid arsenic (As) were reported in the Porto Pozzo and San Teodoro lagoons (9.6 and 6.8 mg kg⁻1 w.w., respectively). The clam R. decussatus confirmed the capacity of bivalves as suitable bioindicators of trace elements pollution. Further investigations are necessary for constant monitoring of clams, 32 which constitute an important traditional resource for the fishing activity in Sardinia.