Direct and indirect causes of sex differences in mercury concentrations and parasitic infections in a marine bird / J.F. Provencher, H.G. Gilchrist, M.L. Mallory, G.W. Mitchell, and M.R. Forbes.
Material type:
TextSeries: Science of the Total Environment. 551-552 506-512 Publication details: 2016Description: 28 cmLOC classification: - PRO
| Item type | Current library | Collection | Call number | Status | Date due | Barcode |
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Electronic Journal
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IWWR Supported Research | Non-fiction | PRO (Browse shelf(Opens below)) | Available | 16686 |
Includes bibliographical references (page 512).
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In many animal species, males and females differ in their levels of contaminants and/or parasitic infections. Most
contaminants and gastro-intestinal parasites are obtained through prey ingestion, and thus the causes of sex differences
in the distribution of these factors might follow similar pathways. We studied the northern common
eider duck (Somateria molissima borealis) as an avian model, and used directed separation path analysis to explore
the causes of sex differences in mercury (Hg) and gastro-intestinal helminths. Two trophically transmitted
helminths were examined: a cestode (Lateriporus sp.) and an acanthocephalan (Polymorphus sp).We found that
the number of Lateriporus sp. varied positively with stable isotope signature (as indicated by δ15N in eider breast
muscle tissue), and negatively with crustaceans being present in the short term diet. We also found that
Polymorphus sp. varied positively with eider tissue stable isotope signature. However, Polymorphus sp. varied
negatively with sex indirectly through condition and liver mass. Similarly, Hg concentrations also varied negatively
with sex indirectly through condition and liver mass, with both Polymorphus sp. intensity and Hg concentrations
significantly higher in males. We found that model fit increased when a negative relationship between
the two helminth species was included, suggesting a yet unknown causal mechanism linking these parasites.
Our findings suggest that although Hg and gastro-intestinal parasites are both trophically transmitted through
the eider's prey items, the factors that contribute towards bioaccumulation of these two burdens differ in source,
likely caused by several different factors and may potentially influence each other.