Skin and hair samples of harbour seals (Phoca vitulina)found dead along the west coast of northern Germany in 1988 were analysed for total mercury, cadmium and lead. Cadmium and lead concentrations were below the detection limit in most skin samples. The mercury content of the hair (median: 23.1 lag g-l wet wt) was several magnitudes higher than the mercury content of the skin (0.27 lag g-i wet wt). Mercury concentrations in hair samples were significantly higher than lead concentrations (0.54 0g g-t wet wt), which significantly exceeded cadmium levels (0.09 l~g g-i wet wt). Female seals revealed lower cadmium concentrations in the hair than male seals. Accumulations of metals with age were observed for cadmium and lead in hair samples and for mercury in skin samples of male seals. A connection between metal accumulation and pigmentation or rather moult was clearly recognizable.Pronounced fluctuations in harbour seal populations of the North Sea have frequently occurred in the last few decades (Reijnders, 1986). The mass mortality of seals in 1988 due to infections of herpes-and morbiliviruses (Haas, 1991) led to one of the strongest decreases of marine mammals ever encountered in this area. Although infection was considered a direct cause of death, pollution effects are likely to favour mortality by weakening the immune system. Chronic exposure~ of organochlorines and trace metals are known to effect the immune system of animals and humans. Mercury, cadmium and lead are particularly pertinent in this respect because of their high toxicities and accumulation properties.Several investigations have been done on the metal burden of inner organs of marine mammals (Koeman et al
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.
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.
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