Mercury trends in herring gull (Larus argentatus) eggs from Atlantic Canada, 1972-2008: Temporal change or dietary shift?
Mercury (Hg) is a pervasive contaminant that can adversely affect predatory wildlife. Bird eggs provide insights into breeding females' Hg burdens, and are easily collected and archived. We present data on Hg trends in herring gull (Larus argentatus) eggs from five sites in Atlantic Canada from 1972 to 2008. We found a significant decrease in Hg at Manawagonish Island, New Brunswick and Île du Corossol, Quebec, but after correcting Hg for dietary shifts using stable isotopes (δ(15)N), these trends disappeared. Decreasing temporal trends of stable isotopes in gull eggs were observed at four sites, suggesting shifts in gull diets. At Gull Island, Newfoundland, diet-adjusted Hg increased from 1977 to 1992, dropped sharply between 1992 and 1996, and rose again from 1996 to 2008. After adjusting Hg trends for dietary shifts of herring gulls, it appears that environmental Hg in coastal ecosystems has remained relatively constant at most sites in Atlantic Canada over the last 36 years.
Environment Canada, 6 Bruce Street, Mount Pearl, Newfoundland and Labrador A1N 4T3, Canada. neil.burgess@ec.gc.ca
Neil M
NM
Burgess
Alexander L
AL
Bond
Craig E
CE
Hebert
Ewa
E
Neugebauer
Louise
L
Champoux
D000818:Animals; D046091:Charadriiformes; D004032:Diet / Q000706:statistics & numerical data; D004784:Environmental Monitoring; D008628:Mercury / Q000032:analysis* / Q000378:metabolism; D009509:New Brunswick; D010063:Ovum / Q000737:chemistry* / Q000378:metabolism; D011792:Quebec; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000378:metabolism; D014877:Water Pollution, Chemical / Q000706:statistics & numerical data*
D014874:Water Pollutants, Chemical; D008628:Mercury