Developing a bioindicator in the northwestern Persian Gulf, Iran: trace elements in bird eggs and in coastal sediments.

Levels of arsenic (As), cadmium (Cd), cobalt (Co), lead (Pb), nickel (Ni), selenium (Se), and vanadium (V) were evaluated in coastal sediments, egg contents, and eggshells of crab plover (Dromas ardeola), bridled tern (Sterna anaethetus), lesser crested tern (S. bengalensis), and western reef heron (Egretta gularis) breeding in the northwestern Persian Gulf. Levels of Cd, Pb, Ni, V, and Se were greater in eggs of terns than in eggs of crab plover, perhaps due to the higher trophic level of terns. Levels of all elements were lower than known effects levels for birds. However, levels of Se in eggs were greater than those known to cause toxic effects in birds. Eggs of terns are ideal for monitoring metal contaminants on the breeding grounds because the bioaccumulation ratios (egg/sediment) of some metals (As, Co, Se) in the eggs of terns are significantly greater compared with those of crab plovers.