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<br /> 40 <br /> EJ SWEITZER LAKE <br />f- - GUNNISON RIVER AT ESCALANTE <br />I 35 STATE WILDLIFE AREA <br />z5:2 11 11 NUMBER OF SAMPLES <br />_w 10 <br />:is: 30 2 <br />0>- <br />-0: <br />!;;:o 25 <br />0::;: <br />f-<( <br />Zo: <br />~l.:) 20 <br />Zo: <br />OW <br />UO- <br />:;:'" 15 <br />::>:;: <br />-<( 8 4 <br />Zo: <br />wl.:) 10 <br />--'0 <br />Wo: <br />"'S,,! 5 <br />:;: <br /> 0 FISH <br /> BIRD BIRD BIRD, WHOLE INVERTE- AQUATIC <br /> LIVERS EGGS BODY BRATES PLANTS <br /> MATRIX <br /> <br /> <br />Figure l8.--Mean concentrations of selenium in biota samples from Sweitzer <br />Lake (site 7) and the Gunnison River at Escalante State Wildlife Area <br />(site 10). <br /> <br />Selenium concentrations greater than 5 ~g/g wet weight (about 17 ~g/g dry <br />weight at 71 percent moisture) in bird eggs will be cause for concern until <br />the chemical forms (selenomethionine is the most toxic) of selenium ingested by <br />birds is known (G.H. Heinz, U.S. fish and Wildlife Service, oral commun., 1990). <br />Also, if selenium concentrations in eggs are greater than 1 ~g/g wet weight <br />(about 3.5 ~g/g dry weight at 71 percent moisture) reproductive success needs <br />to be examined (G.H. Heinz, U.S. Fish and Wildlife Service, oral commun., 1990). <br />Selenium concentrations in eggs collected at Sweitzer Lake (table 23; fig. 19) <br />ranged from 4.1 to 17.6 ~g/g dry weight. No deformities were observed in birds <br />collected from Sweitzer Lake; however, the limited number of eggs collected were <br />less than one-half of the way through incubation, which is too early to detect <br />abnormalities in embryos. Selenium concentrations in the coot egg, the red-winged <br />blackbird egg, and in one of the yellow-headed blackbird eggs collected at <br />Sweitzer Lake (table 23) exceeded the selenium concentration of 10 ~g/g that <br />decreased productivity and duckling survival (Hoffman and Heinz, 1988). The <br />selenium concentrations in those three eggs were within the range of concen- <br />trations (9.1 to 81.4 ~g/g dry weight) reported by Ohlendorf and others (1986) <br />in eggs at Kesterson National Wildlife Refuge, where abnormalities in embryos <br />were detected. <br /> <br />DuBowy (1989) calculated a bioconcentration factor of about 1,430 for <br />selenium from surface water to waterfowl breast muscle. Using that factor, a <br />selenium concentration in Sweitzer Lake of 11 ~g/L (surface-water sample <br />from Sweitzer Lake in November 1987; table 16) would correspond to a selenium <br />concentration of approximately 16 ~g/g wet weight in waterfowl breast muscle. <br /> <br />56 <br />