Study on Metal Concentrations in Tissues of Mallard and Pochard from Two Major Wintering Sites in Southeastern Caspian Sea, Iran

Abstract

We examined concentrations of cadmium, chromium, iron, lead and zinc in the kidney, liver, and pectoral muscle of Mallards (Anas platyrhynchos; n = 30) and Pochards (Aythya ferina; n = 30) from two important wintering sites in the southeastern Caspian Sea in the winter of 2012. Mean lead concentrations (µg g(-1) ww) in livers (2.36 ± 1.00) of Pochard and in kidneys (3.43 ± 0.91) of Mallard exceeded the exposure threshold levels in liver (1.5 µg g(-1) ww) and kidney (3 µg g(-1) ww) of waterfowl. Mean cadmium concentrations in livers (1.63 ± 0.66) of Pochards exceeded the background level of this metal in liver (1 µg g(-1) ww) of waterfowl. Chromium, iron and zinc concentrations were within the normal range as reported in other duck studies. Gender-related and inter-specific variation of metal concentrations in analyzed tissues were observed (t test, p < 0.05). Our results indicated that waterfowl using the Miankalah and Gomishan International Wetlands are being exposed to elevated concentrations of cadmium and lead.

Metal Concentrations in Tissues of Gadwall and Common Teal from Miankaleh and Gomishan International Wetlands, Iran

“…Cadmium concentrations that we observed in the kidneys and liver of Gadwall were higher than noted for ecologically similar species on other areas such as western Iran, southern Poland, and eastern Croatia [ 16 , 25 , 45 ]. However, even higher concentrations were reported by Hassanpour et al [ 31 ] and Sinkakarimi et al [ 55 ] in kidneys and liver of Common Coot (2.11 and 2.22 μg/g ww) and Pochard (2.16 and 1.63 μg/g ww) collected from the same wetlands as our specimens, confirming that waterbirds using Miankaleh and Gomishan International Wetlands are exposed to increased concentrations of Cd. The type of Cd exposure (i.e., acute vs. chronic) may be evaluated on the basis of the ratio of liver to kidney concentrations.…”

“…Thus, Gadwall had greater exposure to Pb than Common Teal, and they may have ingested locally expelled Pb pellets or fishing sinkers since the concentrations we observed were higher than in other waterfowl species from Iran, Poland, Croatia, and Spain; [ 17 , 25 , 45 , 59 ]). The increased exposure to Pb particles was also suspected in other species from the same area in another study in which increased Pb concentrations were observed in livers of Pochards (2.36 μg/g) and Mallards (1.16 μg/g) [ 55 ].…”

“…Metal concentrations did not differ between sexes in the liver and kidneys of Canvasback ( Aythya valisineria ) [ 24 ], liver and blood of Mallard ( Anas platyrhynchos ), Pintail ( Anas acuta ), Shoveler ( Anas clypeata ), and Tufted Duck ( Aythya fuligula ) [ 14 , 50 ]. In contrast, significant differences in Cd, Cu, Mn, Pb, and Zn concentrations between males and females were noted in liver of Scaup ( Aythya marila ) [ 29 ], kidneys, liver, and feathers of Common Coot ( Fulica atra ) and Mallard [ 45 ] and kidneys, liver, and muscles of Pochard ( Aythya ferina ) [ 55 ]. It is likely that differences in foraging habits and physiology between males and females, coupled with season of collection and distribution of elements among habitats, drive differences in exposures between the genders.…”

“…We expected to find significantly increased environmental concentrations of metals, since some reports have identified oil extraction, transportation, inputs from cities, industries and agricultural wastes, and fishery practices as potential sources of pollution in this region [ 5 , 28 , 36 , 52 ]. Previous studies have suggested elevated exposure of waterbirds to Cd and Pb in the area [ 4 , 55 ]. Consequently, we examined the exposure of two species of ducks that we suspected may have elevated exposure to toxic metals in these important wetlands.…”

Lead (Pb) in the tissues of Anatidae, Ardeidae, Sternidae and Laridae of the Northern Hemisphere: a review of environmental studies

“…In gadwall ( Anas strepera ) and common teals ( Anas crecca ) wintering on Miankaleh and Gomishan International Wetlands, located in the southern part of Caspian Sea (northern Iran), the concentrations of lead in the liver were 10.73 and 3.60 μg/g dw (Sinkakarimi et al 2018 ), respectively. Other studies confirm that the Caspian Sea is a highly polluted area—in the livers of mallards and common pochards ( Aythya ferina ), the concentrations of lead were 3.87 ± 1.37 μg/g dw and 7.87 ± 3.33 μg/g dw (Sinka-Karimi et al 2015 ), respectively. At the beginning of the 1990s, in Turkey, environmental contamination with lead was also relatively high.…”