Bioaccumulation of trace elements in migratory waterbirds at two wetlands of Indus river

Waterbirds are used as a bioindicator for analyzing wetland health because they are very sensitive to changes in ecosystems at the nutrient level and through exposure to pollutants. In the present study, bioaccumulation of trace elements (Cu, Zn, Ni, Pb, Co, Cd, and Mn) was investigated in Common Coot Fulica atra, Gadwall Anas strepera, and Eurasian Teal Anas crecca at Taunsa barrage and Chashma barrage located on Indus River, Punjab, Pakistan. Samples of water, sediments, and waterbirds tissues were collected during autumn 2018 and the spring of 2019. Metal concentrations were assessed by using a flame atomic absorption spectrophotometer (Thermo Scientific iCE 3000 Series). We found that the maximum bioaccumulation in birds was of cadmium. Order of metal accumulation was Cd > Pb > Zn > Co > Mn > Cu > Ni (Common Coot) and Cd > Pb > Zn > Co > Cu > Ni > Mn (Gadwall and Eurasian Teal) at Taunsa barrage. At Chashma barrage metal accumulation order was Cd > Zn > Pb > Co > Cu > Mn > Ni (Common Coot), Cd > Zn > Pb > Cu > Co > Ni > Mn (Gadwall) and Cd > Zn > Pb > Co > Cu > Ni > Mn (Eurasian Teal). A. crecca was the species in which the most of the trace elements (Cu, Ni, Pb, Co, and Mn) were accumulated at Taunsa barrage, while at Chashma barrage Zn, Pb, Cd, and Co accumulated in F. atra. Zn, Pb and Cd (avg. > 10) had a high bioaccumulation ratio and Co, Cu, Ni, and Mn (avg. < 10) had low bioaccumulation ratio. When tissues were compared for accumulation, the highest concentrations were observed in the intestine followed by gizzard, probably because of the feeding habits of these waterbirds.