|MadSci Network: Environment & Ecology|
Studies on DDE and eggshell thinning have been done on one very sensitive species-the peregrine falcon. Other predators should have a similar mechanism of eggshell thinning. Miller et al. Nature 259: 122-124.Briefly, lipophillic metabolites of DDT, mainly DDE, are re-released into the blood stream when adipose was used for energy during reproduction or from levels of metabolites obtained via recent prey. While in the uterus, DDE inhibited the enzymes carbonic anhydrase and calcium ATP-ase. This enzyme disruption caused partial blockage of the layering of calcium and carbonate on the eggshell which induced eggshell thinning and disruption of embryo gas transpiration. This, in turn, facilitated eggshell breadage, embryotoxicity and the resulting crash of the pergrine falcon. I don't know about pH changes having an affect on the amount of calcium deposited by the bird.
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