Using the Mallard to biomonitor heavy metal contamination of wetlands in north-western Poland

Contents of iron, zinc, copper, manganese, nickel, lead and cadmium were determined in the brain, pectoral muscle, kidney, liver and bones of the Mallard (Anas platyrhynchos), a cosmopolitan, herbivorous duck species. Both immature (im; in the first year of life) and older (adult, ad) ducks were studied. The birds originated from wetlands in two areas in north-western Poland, one located in the S o sk waterfowl reserve (n=32 im+24 ad) and the other near the city of Szczecin (n=21 im+21 ad). There were numerous significant age-dependent differences in the metal contents of the organs of the Mallards obtained from near Szczecin (Sz) and/or S o sk (S). Copper contents in the brain (Sz and S), muscles (Sz) and kidneys (Sz) as well as cadmium contents in the liver (Sz, S), kidneys (Sz, S) and muscles (S) were observed to increase with age. Between-area differences in metal contents of individual organs were recorded as well. The S Mallard showed higher contents of iron and copper (in muscles, liver and kidneys), zinc (in liver and kidneys) and cadmium (in muscles, liver and kidneys), while the Sz ducks revealed higher contents of manganese and lead (in brain and bones). The differences observed may be related to the habitat specificity: the S o sk reserve is periodically flooded by the River Odra (Oder) waters that carry pollutants from a copper mining area 250 km away. On the other hand, the mid-field ponds near Szczecin are affected by pollutants, including those that are manganese-rich, generated by agriculture and traffic.