Mercury Uptake Affects the Development of Larus fuscus Chicks

Current emission and mobilization rates of mercury (Hg) in the environment pose extensive threats to both wildlife
and human health. Assessing the exposure risk and effects of Hg contamination in model species such as seabirds is essential
to understand Hg risks at the population and ecosystem levels. The lesser black‐backed gull (Larus fuscus), a generalist
seabird species, is an excellent model species because it forages in both marine and terrestrial habitats, which in turn differ in
their Hg exposure risk. To identify possible deleterious effects of Hg exposure on developing L. fuscus chicks, a dietary
experiment was carried out and chicks were provided a marine, terrestrial, or mixed diet. The effects of embryonic and
dietary Hg exposure on chick body condition and physiological state were assessed at different developmental stages until
fledging age (30 d). Overall physiological condition was lower in chicks fed a predominantly marine diet, which coincided
with higher Hg loads in blood and primary feathers. However, no effect of dietary uptake of Hg was observed on body
condition or in terms of genotoxic damage. Body condition and genotoxic damage correlated instead with Hg exposure
during embryonic development, which seems to indicate that embryonic exposure to Hg may result in carry‐over effects on
later chick development.