Contamination of mercury during the wintering period influences concentrations at breeding sites in two migratory piscivorous birds.
Many aquatic fish-eating birds migrate long distances and are exposed to different mercury concentrations ([Hg]) during their annual cycle. Here we examined the importance of migration on [Hg] in two colonial migratory fish-eating bird species. We determined temporal trends of [Hg] and stable isotopes of carbon (δ(13)C) and nitrogen (δ(15)N) during the annual cycle in Double-crested Cormorants (Phalacrocorax auritus) and Caspian Terns (Hydroprogne caspia) breeding in Lake Ontario by a repeated sampling of breast feathers and blood from recaptured individuals. We found an effect of previous winter [Hg], species, sex, and location to explain variations of Hg at breeding sites. This suggests Hg carryover from winter to summer periods and that variations of [Hg] in the summer are partially explained by [Hg] in the winter. Carryover of Hg among seasons and slow changes in [Hg] over time were found especially for individuals in high winter exposure groups, suggesting a slow depuration rate and a fast uptake rate for both species. In contrast, stable isotope values rapidly switched to reach equilibrium at a similar midpoint regardless of winter habitat or diet suggesting minimal carryover of isotopic signatures. The potential of Hg carryover from wintering sites indicates that Hg concentrations in birds at a given time may be influenced by previous exposure from distant locations.
Biology Department, Queen's University , 116 Barrie Street, Kingston, Ontario, Canada K7L3N6.
Raphael A
RA
Lavoie
Christopher J
CJ
Baird
Laura E
LE
King
T Kurt
TK
Kyser
Vicki L
VL
Friesen
Linda M
LM
Campbell
D025041:Animal Migration; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001717:Birds / Q000502:physiology*; D001947:Breeding; D017753:Ecosystem; D004787:Environmental Pollution; D005241:Feathers / Q000737:chemistry; D005260:Female; D005399:Fishes; D008297:Male; D008628:Mercury / Q000032:analysis* / Q000097:blood; D009864:Ontario; D012621:Seasons
D008628:Mercury