Environmental toxins lead to thinner eggshells for Ivory gulls

Environmental toxins lead to thinner eggshells for Ivory gulls. This is one key result of a recent study made by scientists from the Norwegian Polar Institute (NPI), the Russian Antarctic Research Institute (AARI) in St. Petersburg and others. Samples were taken in Svalbard and arctic Russia in 2007. Compared with data from the early 20th century, eggshells from Spitsbergen and the Russian arctic are up to 17 % thinner.

Ivory gulls are on top of the food chain, and long-lived environmental toxins such as PCBs and DDT are accumulating towards the top of the food chain. The thinned eggshells are shown to have high concentrations especially of DDT.

DDT was gradually banned in many countries from the early 1970s onwards and is now used legally only in relatively small quantities to fight diseases such as malaria. After an ban on DDT in Norway, eggshell thickness of seabirds and birds of prey recovered again back to natural values.

Source: Norwegian Polar Institute