Trace elements in lesser scaup (Aythya affinis) from the Mississippi flyway.

Previous research reported that concentrations of selenium in the livers of 88-95% of lesser scaup from locations in Lake Erie, Lake St. Clair, and Lake Michigan, USA were either elevated (10-33 microg/g dry weight [dw]) or in the potentially harmful range (> 33 microg/g dw). In order to determine the geographic extent of these high selenium concentrations, we collected lesser scaup in Louisiana, Arkansas, Illinois, Minnesota, Wisconsin, and Manitoba and analyzed the livers for 19 trace elements. We found that all trace element concentrations, except for selenium, generally were low. Arsenic, which usually is not detected in liver samples, was detected in Louisiana and may be related to past agricultural usages. Chromium, which also is not usually detected, was only present in lesser scaup from Arkansas and may be related to fertilizer applications. Cadmium and mercury concentrations did not differ among locations and concentrations were low. Selenium concentrations in Arkansas (geometric mean = 4.2 microg/g dw) were significantly lower than those in Louisiana (10.7 microg/g dw), Illinois (10.5 microg/g dw), and Minnesota (8.0 microg/g dw); concentrations in Wisconsin and Manitoba were intermediate (6.6 and 6.5 microg/g dw). About 25% of lesser scaup livers contained elevated selenium concentrations; however, none were in the harmful range. We concluded that selenium concentrations in lesser scaup in the Mississippi Flyway are elevated in some individuals, but not to the extent that has been documented in the industrial portions of the Great Lakes.