Data from: Mercury exposure, stress and prolactin secretion in an Arctic seabird: an experimental study

Life-history theory predicts that long-lived organisms should reduce
parental effort under inclement environmental conditions in order to
favour long-term survival. Seabirds are long-lived top predators often
exposed to environmental endocrine disrupting chemicals such as mercury
(Hg). Hg-contaminated birds show disrupted parental behaviour. Avian
parental behaviour is governed by two key hormones in birds:
corticosterone (CORT, a glucocorticoid hormone) and prolactin (PRL, a
pituitary hormone involved in parental care). Any disruption of these
hormones may alter the ability of an individual to adjust parental
behaviour to environmental conditions. The first aim of this study was to
describe the relationships between blood Hg concentrations, plasma PRL and
reproductive performance in Arctic black-legged kittiwakes (Rissa
tridactyla). We a found negative relationship between plasma initial PRL
and blood Hg concentrations in males. Moreover, Hg concentration was
negatively related to breeding success in chick-rearing males. Secondly,
to study the effect of a chronic increase in CORT levels on the Hg–PRL
relationship, we experimentally increased stress with CORT pellet
implantation. We predicted that Hg and CORT would act synergistically on
PRL and an increase in CORT concentration would steepen the Hg–PRL
relationship. However, adding CORT did not steepen the Hg–PRL
relationship. Hatching success was significantly lower in CORT-implanted
males than in controls, and breeding success was not reduced in
CORT-implanted male kittiwakes with high levels of blood Hg. Our results
suggest that Hg may impair reproductive performance through a disruption
of PRL secretion. Contrary to our prediction, Hg and CORT did not act
synergistically and the underlying mechanisms associating CORT and Hg with
PRL might be more complex than a single interaction between two factors.