Is selenium affecting body condition and reproduction in boreal breeding scaup, scoters, and ring-necked ducks? / Jean-Michel A. DeVink, Robert G. Clark, Stuart M. Slattery, and Mark Wayland.

Includes bibliographical references (page 121).

Elevated levels of selenium (Se) have been detected in wintering and spring-staging lesser scaup. Here, we compared spring scaup Se and
mercury (Hg) levels to those of ring-necked ducks and white-winged scoters, species exhibiting increasing and decreasing boreal populations,
respectively. Mercury concentrations were low in all three species. Geometric mean (95%CI) liver Se concentrations were 6.2 (5.5e7.0), 4.6
(4.0e5.4), and 32.6 (28.4e37.3) mg/kg dry weight (dw) in scaup, ringnecks and scoters, respectively. Only scoter livers (66%) were above
33 mg/kg dw Se. Scaup and ringneck Se levels were unrelated to breeding status or lipid and protein levels; breeding scoters and females
with greater lipid mass had higher Se than non-breeders. Egg and follicle concentrations in scaup and scoters were normal (mean
[95%CI] ¼ 2.3 [1.9e2.6] and 2.4 [2.1e2.7] mg/kg dw, respectively). Overall, we found no support for a relationship between selenium and
boreal scaup and scoter declines, and discuss current Se threshold concentrations.