Variation in mercury concentration in juvenile Magellanic penguins during their migration path along the Southwest...

The vulnerability of seabirds related to their migratory dynamics is frequently linked to environmental problems along the migration path. In this context, Magellanic penguins (Sphenicus magellanicus) seem to be vulnerable to an extensive range of environmental disturbances during their northward migration along the Atlantic waters of South America, which include by catch, marine debris ingestion, overfishing and environmental contamination. In this study, we investigate mercury accumulation in muscle and hepatic tissues of juveniles penguins collected along the Brazilian coast during three migratory seasonal years (2006, 2008 and 2012) and three areas along a latitudinal gradient. We found significant differences in Hg levels across the years, with higher hepatic Hg levels found in tissues of penguins sampled in 2008. The higher Hg levels in samples of penguins from 2008 might be attributed to variations in body condition or Hg uptake, associated with the trophic imbalance linked to an extreme El Niño event during that year. Significant differences in Hg accumulation across the latitudinal areas were also observed. The penguins sampled at the farthest area from the breeding ground presented the higher levels of Hg and also the poorest body condition. Body condition and other traits may influence the levels of chemical pollutants and decrease the migratory success rate in the juvenile age phase, compromising population dynamics.