Do foraging ecology and contaminants interactively predict parenting hormone levels in common eider?

Area of Science:

• Arctic ecology
• Environmental toxicology
• Avian reproduction

Background:

• Global climate change causes abiotic shifts in Arctic ecosystems, impacting seabird foraging, body condition, and contaminant exposure.
• Mercury (Hg) exposure and altered foraging ecology may interactively affect reproductive hormones, such as prolactin (PRL), crucial for seabird reproductive success.

Purpose of the Study:

• To investigate the relationship between foraging ecology, mercury exposure, and prolactin levels in Arctic-breeding common eiders.
• To understand the cumulative effects of environmental changes on seabird reproductive hormones.

Main Methods:

• Assessed foraging ecology using stable isotopes (δ13C, δ15N) in 106 incubating female common eiders.
• Measured total mercury (THg) levels and prolactin (PRL) levels in the study population.
• Examined the interactive effects of foraging ecology (δ13C, δ15N) and THg on PRL levels.

Main Results:

• A significant, complex interaction was found between δ13C, δ15N, and THg in predicting PRL levels.
• Individuals foraging at lower trophic levels with higher THg exposure showed a consistent relationship with lowered PRL.
• The combined effect of these variables, particularly foraging in phytoplankton-dominant environments and high Hg levels, resulted in decreased PRL.

Conclusions:

• Environmentally induced changes in foraging ecology and Hg exposure can cumulatively impact reproductive hormones in seabirds.
• These findings highlight the vulnerability of Arctic seabird populations to ongoing climate and food web changes.
• Altered PRL secretion due to combined stressors may have downstream implications for reproductive success in common eiders.