SELENIUM AND MERCURY CONCENTRATIONS IN CALIFORNIA GULLS BREEDING ON THE GREAT SALT LAKE, UTAH, USA

We examined selenium ( Se) and mercury (Hg) concentrations in adult California gulls (Larus californicus) nesting on the Great Salt Lake, Utah, USA, during 2006 and 2007. During 2006, the mean Se concentration (+/- standard error) was 18.1 +/- 1.5 mu g/g in blood on a dry-weight basis and 8.1 +/- 0.4 mu g/g in liver. During 2007, Se concentrations were 15.7 +/- 1.5 mu g/g in blood and 8.3 +/- 0.4 mu g/g in liver; Hg concentrations were 2.4 +/- 0.3 mu g/g in blood and 4.1 +/- 0.5 mu g/g in liver. Gulls collected from a freshwater colony located within the watershed of the Great Salt Lake had similar levels of Se in the blood and liver as gulls collected on the Great Salt Lake but lower Hg concentrations. Body mass of adult gulls was not correlated with Se or Hg concentrations in their blood or liver. Selenium concentration in California gull eggs collected during 2006 was 3.0 +/- 0.10 mu g/g. Of 72 eggs randomly collected from Great Salt Lake colonies, only one was infertile, and none of the embryos exhibited signs of malposition or deformities. We examined 100 newly hatched California gull chicks from Great Salt Lake colonies for teratogenesis; all chicks appeared normal. Hence, the elevated Se and Hg concentrations in adult gulls nesting on the Great Salt Lake did not appear to impair gulls' health or reproductive ability.