Mercury in egg and eggshell of Whiskered Tern (Chlidonias hybrida) from Anzali wetlands of the Caspian Sea, Iran.

Mercury content of egg and eggshell from Whiskered Terns of Anzali wetlands of the Caspian Sea were determined. Mercury levels in egg content of both abandoned (433 ± 4) and non-abandoned (459 ± 15) eggs were 150 times greater than eggshells. Eggshell thickness differed between non-abandoned (0.5 ± 0.03) and abandoned eggs (0.6 ± 0.5) (p < 0.001). No significant association was found between shell Hg and shell thickness in this study. There was significantly more Hg in egg content than in shell (p < 0.001). Mercury levels in eggs did not exceed the levels associated with adverse reproductive effects.