Trace Elements in Mediterranean Mussels Mytilus galloprovincialis from the South African West Coast

Invasive bivalve molluscs, Mediterranean mussels (Mytilus galloprovincialis) were used as sentinel biomonitors of pollution by inorganic contaminants in Saldanha Bay and the Langebaan Lagoon area of South Africa. Two complementary analytical techniques, ICP-MS and NAA, allowed for determination of concentrations of 31 major and trace elements including heavy metals and arsenic in the soft tissues of the mussels. Distinct seasonal patterns were found in the dynamics of these concentrations, with the mussels accumulating much more trace elements in winter than in the summer. In general, the mussels that grew naturally also demonstrated higher concentrations of As, Cd, Fe, Hg and Zn than those that were farmed. Fe showed the highest levels with a maximum concentration of 444 mg/kg followed by Zn with a maximum of 228 mg/kg. The concentrations of Mn and Pb were significantly higher in the Port of Saldanha close to the jetty where ores containing these metals are loaded in comparison with the other sampling sites. It was concluded that bivalve molluscs present themselves as effective biomonitors when assessing marine aquatic pollution by inorganic contaminants in the Saldanha Bay region.