The suitability of oiled guillemots (Uria aalge) as monitoring organisms for geographical comparisons of trace element contaminants.

The influence of the nutritional state (condition factor), age, and sex of Common Guillemots (Uria aalge) on trace element levels was examined to investigate the validity of geographical comparisons of metal accumulations in dying and dead oiled seabirds. A quotient of liver mass to kidney mass was calculated as a condition factor. Condition factors ranged from 0.85-4.74. Sex did not alter the distribution of any of the elements analyzed in immature or adult birds. Cadmium concentrations in soft tissues were strongly influenced by the age of the birds, with adult birds containing significantly higher amounts (0.025-88.28 ppm) than immature ones (0. 004-17.9 ppm). When simultaneously considering age and nutritional condition of the birds, selenium levels were highest in liver samples in immature guillemots (7.37-41.27 ppm) as compared to adult birds (7.22-36.84 ppm). Mercury, copper, and zinc were independent of age. The condition factor had no effect on cadmium levels in birds. In contrast, copper and zinc concentrations in kidney, liver and feathers were negatively correlated with the nutritional condition. In the case of mercury a similar relationship was found only in feathers. On the basis of these results guillemots collected in the German Bight showed significantly higher mercury values (0. 81-20.87 ppm) in soft tissues than birds collected in Brittany (0. 85-17.95 ppm). In general, cadmium levels were higher in the liver of immature birds from the German Bight than in those from Brittany. With regard to copper and zinc only kidney samples had higher values in the German Bight than in Brittany. Selenium levels were lower in feathers of birds from the German Bight (0.09-2.20 ppm) than in those from Brittany (0.67-6.64 ppm). The results indicate that beached guillemots can be used to monitor geographical differences in the contamination with certain metals provided that birds of the same age and/or nutritional condition are compared.