Mercury and other Contaminants in Common Loons Breeding in Atlantic Canada

Abstract

Common loons (Gavia immer) were studied to assess the biomagnification of persistent contaminants in lake ecosystems in Atlantic Canada. Forty-two breeding adults and 20 juvenile loons were captured in August, 1995-1997 on lakes in four areas of southern New Brunswick (Lepreau and Fundy National Park) and Nova Scotia (Halifax and Kejimkujik National Park). Blood samples were collected for analysis of mercury, methylmercury, lead, and selenium. Plasma samples from adult loons were analyzed for PCB congeners and organochlorine pesticides. Secondary flight feathers were collected from adult loons for mercury analysis. Kejimkujik loons had significantly higher geometric mean concentrations of mercury in blood (adults: 5.5 microg/g, wet wt) and feathers (adults: 15 microg/g, fresh wt), and higher levels of PCBs, DDE, oxychlordane, trans-nonachlor, mirex and hexachlorobenzene than loons at Halifax or Lepreau. Blood selenium levels were lowest in Kejimkujik loons. Selenium and mercury concentrations were negatively related in blood of adults across all sites. Adult males had higher concentrations of mercury in blood and feathers and PCBs, DDE, and oxychlordane in plasma, and lower levels of selenium in blood, than adult females. Juvenile loons had lower blood mercury and selenium concentrations than adults. Several contaminants showed significant inter-lake variation within the study sites. Mean blood mercury concentrations in Kejimkujik loons are the highest found in breeding common loons across North America. Of adult loons at Kejimkujik, 92% had blood mercury levels > 4 microg/g (wet wt), which have been associated with impaired reproduction, elevated corticosterone levels, asymmetry in plumage development, and altered breeding behavior in loons there and elsewhere.

Lead, Mercury, Selenium, and Other Trace Elements in Tissues of Golden Eagles From Southwestern Montana, Usa

“…Only one Golden Eagle, an adult male, had a mercury level (0.50 ppm) in blood above that considered background in piscivorous birds (0.4 ppm; Eisler, 1987;Burgess et al, 2005). Only one eagle had a selenium blood level below background, but no eagles had levels above those considered toxic in birds (0.2 and 2.0 ppm, respectively; Eisler, 1985;Burgess et al, 2005).…”

“…We avoided use of category names based on clinical veterinary experiences because we sampled free-flying Golden Eagles that were not injured and/or overtly expressing signs of lead poisoning, but retained ascending exposure level concentration ranges comparable to those found in other studies (Kramer and Redig, 1997;Stauber et al, 2010). Exposure levels for other trace elements in blood that potentially may affect health and reproduction have been established for some mammal and bird species (e.g., Burgess et al, 2005;Burger and Gochfeld, 2009) but not Golden Eagles.…”

Common Loon, <em>Gavia immer</em>, Breeding Success in Relation to Lake pH and Lake Size Over 25 Years

“…Eastern North America receives Hg through atmospheric deposition that is magnified millions of times as it rises up the aquatic food chain to loons (Driscoll et al 2007b). Elevated Hg levels in loons or their prey have been related to reductions in egg-laying, in nest fidelity, in territorial fidelity, in time spent back-riding by chicks, and in productivity; elevated corticosterone levels; lethargy; compromised immune systems; and asymmetry in plumage development (Barr 1986;Nocera and Taylor 1998;Burgess et al 2005;Burgess and Meyer 2007;Evers et al 2007;Kenow et al 2007). Hg levels in loons and their prey are often related negatively to lake pH (Meyer et al 1995(Meyer et al , 1998.…”

Avian Resources of the Northern Gulf of Mexico

“…Birds that eat large fish with the highest mercury levels are most at risk (Pinho et al 2002;Storelli et al 2002;Burger 2009;Burger et al , 2011Frederick et al 1999Frederick et al , 2004. Common Loons Burgess et al 2005;Burgess and Meyer 2008;Evers et al 2008), raptors (Albers et al 2007), and songbirds (Jackson et al 2011) are species with high mercury levels that have impaired reproduction, with possible population declines.…”

“…Common Loons are used as indicators of environmental health in the northeast because of documented effects from acid rain and mercury Nocera and Taylor 1998;Burgess et al 2005;Burgess and Meyer 2008;Evers et al 2008). They also are useful indicators The last five columns are habitat categories in the Gulf of Mexico because they swim on the surface and dive for relatively large fish that are 10-15 cm long or more (Imhof 1962).…”