doi:10.1016/j.scitotenv.2007.02.013 
Published by Elsevier B.V.
Vitamin A and contaminant concentrations in surf scoters (Melanitta perspicillata) wintering on the Pacific coast of British Columbia, Canada
M.L. Harrisa, L.K. Wilsonb, S.F. Trudeauc and J.E. Elliottb, 
, 
aLorax Environmental, 136 St. Catherine's Rd, RR3 Bonshaw, PE, Canada C0A 1C0
bPacific Wildlife Research Centre, Environment Canada, 5421 Robertson Rd., RR1 Delta, BC, Canada V4K 3N2
cNational Wildlife Research Centre, Environment Canada, Ottawa, ON, Canada K1A 0H3
Received 5 December 2006;
revised 1 February 2007;
accepted 3 February 2007.
Available online 3 April 2007.
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Abstract
Surf scoters are part of a community of sea ducks on the western coast of North America that have shown signs of long-term, unexplained declines in breeding bird numbers. Substantial numbers of scoters winter in the major harbours on the west coast, after breeding in the west-central northern boreal forest. To address the potential for contaminants to impact the health and survival of those birds, we investigated the condition and contamination of surf scoters during the winters of 1998–2001 at four foraging locations in the Strait of Georgia region of the Pacific coast of Canada. Vitamin A status was evaluated in liver and plasma samples collected from adults and juveniles, as part of a larger assessment of tissue contamination, body condition and biomarker responses. Individuals collected from a relatively contaminated site, Howe Sound, showed consistently low hepatic concentrations of retinol and retinyl palmitate forms of vitamin A, and gender-specific associations of retinyl palmitate with hepatic EROD activity. The relationship of hepatic retinol to retinyl palmitate was not constant across geographic locations, and a clear, linear relationship between the two forms of vitamin A was only evident in birds from the relatively uncontaminated site. This study also identified strong positive relationships between vitamin A and tissue burdens of cadmium and zinc. The positive association between hepatic retinyl palmitate and renal cadmium is similar to one observed in laboratory rats, in which a mechanism of interference with the controlled release of retinol from the liver was suggested.
Keywords: Retinol; Contaminants; EROD; Sea ducks; Cadmium; Zinc
Fig. 1. Collection sites for wintering surf scoters in the Strait of Georgia, BC, Canada.
Fig. 2. The variable relationship between hepatic concentrations of retinyl palmitate and retinol in surf scoters collected from three different locations in the Strait of Georgia, BC, Canada, 1998–2001. Open circles represent females (adult, sub-adult and juvenile), closed triangles represent adult and sub-adult males, open triangles represent juvenile males, solid lines represent slopes of linear regressions conducted using data for adult males (females and immatures are included on the graph for visual comparative purposes only). Regression equations and significance values are reported in the Results text.
Fig. 3. The gender-specific association between hepatic ethoxyresorufin-o-deethylase (EROD) activity and concentrations of retinyl palmitate in surf scoters collected from Howe Sound in the 1998–99 winter season. Open circles = females, closed triangles = males, solid line = linear regression for males, broken line = linear regression for females. Regression equations and significance values are reported in the Results text.
Table 1.
Concentrations of hepatic retinol, retinyl palmitate (μg·g− 1 ww) and plasma retinol (μg·L− 1) in surf scoters collected from over-wintering foraging grounds in the Strait of Georgia, BC, Canada, 1998–2001a
aValues are geometric means with range in parentheses. Adult categories include a small number of sub-adults (2-year-olds), as they may be sexually mature.
Table 2.
Summary of significant results of stepwise multiple regressions, testing the dependency of hepatic concentrations of retinyl palmitate on hepatic retinol and renal concentrations of cadmium or zinc in surf scoters collected from over-wintering foraging grounds in the Strait of Georgia, BC, Canada, 1998–2001a
aRp = retinyl palmitate, Rn = retinol; sample n includes 40 adult males, 13 adult females, 8 juvenile males (large sample set only), 10 juvenile females (large sample set only).
Table 3.
Concentrations of cadmium and zinc (geometric mean, range (n)) in kidneys of surf scoters from the southern coast of BC, Canada, 1998–2001 (from Elliott et al., 2007)a
aAll concentrations expressed in μg·g− 1 dw.
bSome mature males from Elliott et al. (in press).
Abstract
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