25 



were approximately the same in 1968 and 

 1969, averaging about 0.52 ppm, with the 

 upper extreme concentration of 0.67 ppm. 

 Even higher levels of mercury (3.7 ppm) were 

 found in muscle tissue of great cormorants 

 than in muscle of murres (0.9 ppm) or black 

 guillemots (1.8 ppm) from the Baltic. Mercury 

 in feathers (up to 51 ppm), muscle (up to 

 26 ppm), and brains (up to 14 ppm) of white- 

 tailed eagles exceeded the levels in other 

 species. Mercury concentrations in the kid- 

 neys (48-123 ppm) and muscle tissue (1.9- 



8.5 ppm) of other white-tailed eagles from the 

 same area further indicate that the species 

 may have serious mercury pollution problems 

 (Henriksson et al. 1966). Bald eagles in the 

 United States also occasionally contain high 

 levels of mercury (up to 43 ppm) in their car- 

 casses (Belisle et al. 1972). 



Mercury levels (figures not specifically 

 stated) in the muscle of eiders and sandwich 

 terns of the Dutch Wadden Sea appear 3 to 

 5 times higher than the levels considered rep- 

 resentative of natural background (de Goeij 

 1971). Analyses were also made of various 

 organs of three common murres and one 

 razorbill that were found as oiled birds along 

 the Dutch coast (Koeman et al. 1975): mer- 

 cury in the livers did not exceed 2.5 ppm; sele- 

 nium in the liver of one common murre was 



4.6 ppm, but the levels of these metals were 

 not correlated with each other. 



There were no significant geographical or 

 species differences in two essential heavy 

 metals (copper and zinc) in Antarctic and 

 North American petrels (Anderlini et al. 

 1972). Silver, cobalt, and lead were difficult to 

 detect at the low levels that were found, but 

 there were no detectable differences in their 

 concentrations. Cadmium, chromium, nickel, 

 and mercury levels in petrels suggested a cor- 

 relation of increasing concentration with in- 

 creased exposure to industrialized areas. 

 Higher concentrations of these metals in ashy 

 petrels are probably the result of their feeding 

 in the proximity of San Francisco Bay. 



Livers from ruddy ducks killed by an oil 

 spill on the Delaware River contained detect- 

 able levels of lead, cadmium, and mercury 

 (White and Kaiser 1976). Lead ranged from 

 0.19 to 0.61 ppm, cadmium from 0.27 to 

 1.60 ppm, and mercury from 0.06 to 

 0.74 ppm. Residues of these metals were simi- 

 lar to those found in canvasbacks from the 



Chesapeake Bay region (D. H. White and 

 R. C. Stendell, unpublished manuscript). 



Mercury residues in the livers of six gannets 

 from the Irish Sea (4 ppm; 18.4 ppm dry 

 weight) averaged higher than in two gannets 

 from eastern Scotland (1.6 ppm; 7.3 ppm dry 

 weight) that died during unrelated large-scale 

 mortality incidents (Parslow et al. 1973). 

 Average levels of copper (7.4 ppm; 34 ppm 

 dry weight) and zinc (64.8 ppm; 298 ppm dry 

 weight) in the livers of gannets from the Irish 

 Sea also were higher than in two others from 

 eastern Scotland (2.8 ppm copper; 26.3 ppm 

 zinc). The differences in the metal concentra- 

 tions between the two groups were considered 

 the result of the differences in liver sizes. Al- 

 though the cause of the gannet deaths could 

 not be established, heavy metal concentra- 

 tions in the birds apparently were responsible 

 for the death of only one individual with high 

 mercury levels (22 ppm; 98 ppm dry weight). 

 Lead and cadmium concentrations were below 

 the limits of detection in all of these birds, but 

 another gannet that died in an earlier incident 

 had measurable residues of lead (0.2 ppm) and 

 cadmium (2.0 ppm). 



Mercury concentrations in the livers and 

 kidneys of common murres that died in the 

 seabird wreck in the Irish Sea during autumn 

 1969 did not exceed 5 ppm (23 ppm dry 

 weight) (Holdgate 1971). Some of the birds 

 showed relatively high levels of particular 

 metals and in some the highest concentra- 

 tions were above the level at which poisoning 

 may have occurred. However, in general, the 

 range of mercury levels in the casualties of the 

 incident and in the healthy birds shot for com- 

 parison overlap. The levels of mercury (up to 

 5 ppm), lead (8.7 ppm), cadmium (2.8 ppm), 

 and arsenic (8.3 ppm) in the livers and kid- 

 neys of some birds appeared elevated. 



Biological Effects of Heavy 

 Metals on Marine Birds 



Toxicology, Physiology, and Pathology 



In 1953 a severe neurological disorder 

 caused by mercury poisoning was first recog- 

 nized among people living in the vicinity of 

 Minamata Bay, Japan (Kurland et al. 1960). 

 Toxic effects and similar histopathological 

 changes have been reported for fish, birds, 

 and mammals that died as a result of mercury 



