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 se x of Common Guillemots (Uria aalge) on trace element levels was examin ed to investigate the validity of geographical comparisons of metal ac cumulations in dying and dead oiled seabirds. A quotient of liver mass to kidney mass was calculated as a condition factor. Condition factor s ranged from 0.85-4.74. Sex did not alter the distribution of any of the elements analyzed in immature or adult birds. Cadmium concentratio ns in soft tissues were strongly influenced by the age of the birds, w ith adult birds containing significantly higher amounts (0.025-88.28 p pm) than immature ones (0.004-17.9 ppm). When simultaneously consideri ng age and nutritional condition of the birds, selenium levels were hi ghest in liver samples in immature guillemots (7.37-41.27 ppm) as comp ared to adult birds (7.22-36.84 ppm). Mercury, copper, and zinc were i ndependent of age. The condition factor had no effect on cadmium level s in birds. In contrast, copper and zinc concentrations in kidney, liv er and feathers were negatively correlated with the nutritional condit ion. In the case of mercury a similar relationship was found only in f eathers. On the basis of these results guillemots collected in the Ger man Eight 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 fro m the German Bight than in those from Brittany. With regard to copper and zinc only kidney samples had higher values in the German Eight tha n in Brittany. Selenium levels were lower in feathers of birds from th e German Eight (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 moni tor geographical differences in the contamination with certain metals provided that birds of the same age and/or nutritional condition are c ompared.