THE INFLUENCE OF AGE ON CADMIUM CONCENTRATIONS IN SEABIRDS

The effects of age on cadmium concentrations was investigated in Gory' s shearwater, Calonectris diomedea, Lesser black-backed gull, Larus fu scus, and great skuas, Catharacta skua. There was no evidence for the continued accumulation of cadmium with increasing adult age. Adult she arwaters did have higher concentrations of cadmium compared to young f ledglings, but there was no significant difference between cadmium con centrations in adult and sub-adult gulls. In addition, the sample of g reat skuas were of known age (3-22 yrs old) and showed no evidence of increasing cadmium concentrations with adult age in liver or kidney. H owever, it is possible that age accumulation of cadmium in great skuas was masked by individual dietary preferences overriding the effects o f increasing age. It is often assumed that cadmium concentrations cont inue to accumulate with increasing adult age, but seabirds may have ev olved some as yet unknown mechanism for excretion or more rapid turnov er of cadmium than previously thought. The implications of this for th e use of seabirds as biomonitors is discussed.