Pattern of Mercury Allocation into Egg Components is Independent of Dietary Exposure in Gentoo Penguins |
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Authors: | Email author" target="_blank">Rebecka?L?BrassoEmail author Stephanie?Abel Michael?J?Polito |
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Institution: | (1) University of North Carolina, Wilmington, NC, USA;(2) Henry Doorly Zoo, Omaha, NE, USA |
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Abstract: | Avian eggs have become one of the most common means of evaluating mercury contamination in aquatic and marine environments
and can serve as reliable indicators of dietary mercury exposure. We investigated patterns of mercury deposition into the
major components of penguin eggs (shell, membrane, albumen, and yolk) using the Gentoo penguin (Pygoscelis papua) as a model species. Eggs were collected from both wild and captive populations of Gentoo penguins to compare the allocation
of mercury into individual egg components of birds feeding at disparate trophic positions as inferred by stable isotope analysis.
Mercury concentrations in captive penguins were an order of magnitude higher than in wild birds, presumably because the former
were fed only fish at a higher trophic position relative to wild penguins that fed on a diet of 72–93% krill (Euphausia spp.). Similar to previous studies, we found the majority of total egg mercury sequestered in the albumen (92%) followed
by the yolk (6.7%) with the lowest amounts in the shell (0.9%) and membrane (0.4%). Regardless of dietary exposure, mercury
concentrations in yolk and membrane, and to a lesser degree shell, increased with increasing albumen mercury (used as a proxy
for whole-egg mercury), indicating that any component, in the absence of others, may be suitable for monitoring changes in
dietary mercury. Because accessibility of egg tissues in the wild varies, the establishment of consistent relationships among
egg components will facilitate comparisons with any other study using eggs to assess dietary exposure to mercury. |
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