Mercury Exposure in Breeding Common Loons (Gavia Immer) in Central Ontario, Canada

Scheuhammer, Anton M.; Atchison, Carolyn M.; Wong, Allan H. K.; Evers, David C.

doi:10.1897/1551-5028(1998)017<0191:meibcl>2.3.co;2

Cited by 61 publications

(68 citation statements)

References 25 publications

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“…The higher Hg concentrations in blood and feathers of male loons compared to females is consistent with findings from elsewhere in North America Meyer et al, 1998;Scheuhammer et al, 1998b;Champoux et al, 2005). Geometric mean blood and feather Hg levels in females were 84% and 76% that of males, respectively.…”

Section: Discussionsupporting

confidence: 88%

Mercury and other Contaminants in Common Loons Breeding in Atlantic Canada

2005

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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.

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Section: Discussionsupporting

confidence: 88%

Mercury and other Contaminants in Common Loons Breeding in Atlantic Canada

2005

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“…Particular emphasis has been placed on larger species for which trophic status is potentially greatest; such species include the common loon (Meyer et al, 1995Burgess et al, 1998a, b;Evers et al, , 2003Scheuhammer et al, 1998bScheuhammer et al, , 2001Fevold et al, 2003;Burgess and Hobson, in press;Champoux et al, in press), bald eagle (Grier, 1974;Wiemeyer et al, 1984;Frenzel and Anthony, 1989;Bowerman et al, 1994;Anthony et al, 1999;Bowerman et al, 2002), osprey (Cahill et al, 1998;DesGranges et al, 1998), wading birds (Gariboldi et al, 1998;Bouton et al, 1999;Spalding et al, 2000b;Henny et al, 2002), and seabirds (Braune, 1987;Burger and Gochfeld, 1995;Furness, 1995, 1997;Braune et al, 2001). Other foodweb pathways important for MeHg transfer are generally of lesser concern because trophic status of the endpoint species is generally lower than piscivores.…”

Section: Species Hg Exposure Patternsmentioning

confidence: 99%

Patterns and Interpretation of Mercury Exposure in Freshwater Avian Communities in Northeastern North America

et al. 2005

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Abstract. A large data set of over 4,700 records of avian mercury (Hg) levels in northeastern North America was compiled and evaluated. As Hg emissions remain poorly regulated in the United States and Canada, atmospheric deposition patterns and associated ecological responses continue to elicit interest by landscape managers, conservation biologists, policy makers, and the general public. How avian Hg exposure is interpreted greatly influences decision-making practices. The geographic extent and size of this data set is valuable in understanding the factors that affect the exposure of Hg to birds. Featured are differences found among tissues, major aquatic habitats and geographic areas, between age class and gender, and among species. While Hg concentrations in egg and blood reflect short-term Hg exposure, Hg concentrations in liver and feather provide insight into long-term Hg exposure. Blood is a particularly important matrix for relating site-specific exposure to methylmercury (MeHg). The level of MeHg is generally 5-10x greater in adults compared to nestlings. Age also influences MeHg bioaccumulation, particularly for individuals where MeHg intake exceeds elimination. Gender is of interpretive concern when evaluating Hg exposure for species exhibiting sexual dimorphism and niche partitioning. Based on two indicator species, the belted kingfisher (Ceryle alcyon) and bald eagle (Haliaeetus leucocephalus), we found MeHg availability increased from marine, to estuarine and riverine systems, and was greatest in lake habitats. A large sample of >1,800 blood and egg Hg levels from the common loon (Gavia immer) facilitated a suitable comparison of geographic differences. Although some clusters of highly elevated Hg exposure (i.e., blood levels >3.0 lg/g, ww and egg levels >1.3 lg/g, ww) were associated with hydrological and biogeochemical factors known to increase MeHg production and availability, others were not. Geographic areas without a relationship between Hg exposure and biogeochemical processes were associated with emission or waterborne point sources. Differences in Hg exposure among species are primarily correlated with trophic position and availability of MeHg. Although piscivorous species were repeatedly *To whom correspondence should be addressed: Tel.: 207-839-7600; Fax: 207-839-7655; E-mail: david.evers@briloon.org Ecotoxicology, 14, 193-221, 2005 Ó 2005 shown to have some of the highest MeHg levels of the 38 species analyzed, insectivorous birds in both aquatic and terrestrial habitats (such as montane areas) were also found with elevated MeHg levels. A better understanding of the factors confounding interpretation of Hg exposure provides an effective basis for choice of indicator species and tissues according to 12 selected scenarios. This and the national need for spatiotemporal monitoring of MeHg availability require careful consideration of indicator species choice. Only then will local, regional, continental, and even global monitoring efforts be effective.

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“…Therefore, we selected a NEHC of 0.5 μg/g developed specifically to estimate mercury risk to bald eagles , which resulted in considerably lower estimates of risk to bald eagles at our sites; only nine sites had mercury concentrations >0.5 μg/g. However, there is evidence that piscivorous birds are being negatively affected by mercury in fish elsewhere (e.g., Scheuhammer and Blancher 1994;Scheuhammer et al 1998;Nocera and Taylor 1998). One might therefore argue that bald eagle populations would be increasing more rapidly if not for mercury, which would support the use of the lower TRVs.…”

Section: Dieldrin -Mink Dieldrin -Bald Eaglementioning

confidence: 99%

“…Bald eagles and mink consume large, adult fish such as those collected and analyzed in this study and are therefore reasonable receptors. The risk of contaminants to other piscivorous wildlife such as belted kingfisher (Ceryle alcyon), Caspian tern (Sterna caspia), or common loons (Gavia immer) may be overestimated if these species are used in the model, because they consume smaller fish that are presumed to have lower contaminant concentrations than larger fish because of their shorter lifespans, higher growth rates, and higher metabolism (Scheuhammer et al 1998;Rose et al 1999). It is also unlikely that the diet of adult bald eagles or mink would be entirely composed of fish from one site, which is tacitly assumed in this approach.…”

Section: Dieldrin -Mink Dieldrin -Bald Eaglementioning

confidence: 99%

Environmental contaminants in freshwater fish and their risk to piscivorous wildlife based on a national monitoring program

Hinck

Schmitt

Chojnacki

et al. 2008

Environ Monit Assess

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Organochlorine chemical residues and elemental concentrations were measured in piscivorous and benthivorous fish at 111 sites from large U.S. river basins. Potential contaminant sources such as urban and agricultural runoff, industrial discharges, mine drainage, and irrigation varied among the sampling sites. Our objectives were to provide summary statistics for chemical contaminants and to determine if contaminant concentrations in the fish were a risk to wildlife that forage at these sites. Concentrations of dieldrin, total DDT, total PCBs, toxaphene, TCDD-EQ, cadmium, chromium, mercury, lead, selenium, and zinc exceeded toxicity thresholds to protect fish and piscivorous wildlife in samples from at least one site; most exceedences were for total PCBs, mercury, and zinc. Chemical concentrations in fish from the Mississippi River Basin exceeded the greatest number of toxicity thresholds. Screening level wildlife risk analysis models were developed for bald eagle and mink using no adverse effect levels (NOAELs), which were derived from adult dietary exposure or tissue concentration studies and based primarily on reproductive endpoints. No effect hazard concentrations (NEHC) were calculated by comparing the NOAEL to the food ingestion rate (dietary-based NOAEL) or biomagnification factor (tissue-based NOAEL) of each receptor. Piscivorous wildlife may be at risk from a contaminant if the measured concentration in fish exceeds the NEHC. Concentrations of most organochlorine residues and elemental contaminants represented no to low risk to bald eagle and mink at most sites. The risk associated with pentachloroanisole, aldrin, Dacthal, methoxychlor, mirex, and toxaphene was unknown because NOAELs for these contaminants were not available for bald eagle or mink. Risk differed among modeled species and sites. Our screening level analysis indicates that the greatest risk to piscivorous wildlife was from total DDT, total PCBs, TCDD-EQ, mercury, and selenium. Bald eagles were at greater risk to total DDT and total PCBs than mink, whereas risks of TCDD-EQ, mercury, and selenium were greater to mink than bald eagle.

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Mercury Exposure in Breeding Common Loons (Gavia Immer) in Central Ontario, Canada

Cited by 61 publications

References 25 publications

Mercury and other Contaminants in Common Loons Breeding in Atlantic Canada

Mercury and other Contaminants in Common Loons Breeding in Atlantic Canada

Patterns and Interpretation of Mercury Exposure in Freshwater Avian Communities in Northeastern North America

Environmental contaminants in freshwater fish and their risk to piscivorous wildlife based on a national monitoring program

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