Biomonitoring of mercury pollution in a wetland near Ravenna, Italy by translocated bivalves (Mytilus galloprovincialis)

An active biomonitoring experiment using mussels (Mytilus galloprovincialis ) was performed in Pialassa Baiona, a mercury-polluted coastal wetland near Ravenna, Italy. Three stations (A, B, and C) were selected along the south to north axis. Following a 52-d field exposure, organisms transplanted in the southernmost polluted area (station A) showed mean mercury concentratio n values of 660 ng/g (dry weight), 4.4 times the initial background level, and were still accumulating mercury. Mussels in both the central area (stat ion B) and the northern area (station C) seemed to reach a steady state wit h mean mercury concentration values of 323 and 412 ng/g, respectively. This field experiment is the first study carried out in the Ravenna wetlands to evaluate mercury bioavailability in this environment. Finally, the efficie ncy of the population of Mytilus galloprovincialis selected for the field e xperiment as mercury bioaccumulators was tested in a laboratory experiment that revealed that up to 135 mu g/g (dry weight) could be reached after 77 d of exposure to mercury-polluted water.