The biomonitoring approach as a tool of trace metal assessment in an uncontaminated marine ecosystem: The island of Ustica (Sicily, Italy)

Marine organisms were tested as possible biomonitors of heavy metal contamination in a reference marine ecosystem, in Ustica (an island of the Southern Tyrrhenian Sea). The goal of this preliminary work is to evaluate the concentrations of Cu, Zn and Pb, using two gastropod molluscs, Monodonta turbinata Born and Patella caerulea L. Samples were collected in the tidal zone, at five coastal stations, according to their availability. Namely, the stations included the Marine Reserve (a “Marine Park” area), which is an uncontaminated site, and the Harbour station, where the contamination level was expected to be higher than the other sites. In order to gain additional information on both the environmental conditions of the area and possible bioaccumulation patterns, seawater samples were also collected in each site to assess soluble metal concentrations. Statistical analyses (one way ANOVA and multiple comparison tests) were applied to test the differences between metal concentrations in different sites and species. Results show high concentration factors (CFs) with respect to the concentrations in marine waters (soluble fraction). This confirms the suitability of these species for biomonitoring purposes. The metal concentrations recorded at the stations generally fall in the range of the lowest values available in the literature and may be considered as useful background levels to which to refer for intraspecific comparison within the Mediterranean area.