29 



averaged 0.86 ppm. Hens fed mercury made 

 less efficient use of feed and laid a greater per- 

 centage of their eggs outside their nest boxes 

 compared with controls. They also produced 

 fewer 1- week-old ducklings than did controls, 

 although there had been no difference in duck- 

 ling production by their parents fed 0.5 ppm 

 mercury in the preceding years. The ducklings 

 from dosed parents did not grow as fast as did 

 those from controls. 



Black ducks given a diet containing 3 ppm 

 mercury (dry weight) as methyl mercury 

 hatched fewer eggs than did controls and 

 fewer of their ducklings survived (Finley and 

 Stendell 1978). Average mercury residues in 

 brain, liver, and muscle of ducklings that died 

 (3.7, 9.4, and 4.9 ppm) were about twice those 

 in tissues of ducklings sacrificed at 4 weeks of 

 age (1.6, 5.7, and 2.1 ppm). 



Mercury residues in pheasant eggs were 0.9 

 to 3.1 ppm following administration of 

 4.2 ppm mercury (dry weight) in their diet 

 (Spann et al. 1972). The birds exhibited 

 greatly reduced egg production and increased 

 embryo mortality in the few eggs laid. 



Mercury residues in bobwhite eggs from 

 birds fed a dietary concentration of 1.7 ppm 

 (dry weight; administered as ethyl mercury 

 p-toluene sulfonanilide) averaged 1.6 ppm 

 (J. W. Spann and R. G. Heath, unpublished 

 manuscript). There was a significantly greater 

 mortality among young whose parents re- 

 ceived mercury in the diet. The principal 

 period of increased mortality included the last 

 5 days of incubation and the first day aiter 

 hatching. 



Behavior 



The behavior of mallard ducks whose par- 

 ents were fed a control diet or a diet contain- 

 ing 0.5 or 3.0 ppm mercury (dry weight) as 

 methyl mercury was studied (Heinz 1975). 

 There was no significant difference among 

 controls and ducklings from mercury-treated 

 parents in the percentage of ducklings that 

 approached the tape-recorded maternal call. 

 However, control ducklings moved back and 

 forth toward the call more than ducklings 

 from mercury-treated parents and also spent 

 more time in the end of the runway near the 

 loudspeaker than ducklings whose parents 

 were fed a diet containing 0.5 ppm mercury. 



Compared to control ducklings, those from 

 parents fed a diet containing either mercury 

 concentration were hyper-responsive in avoid- 

 ance behavior tests. 



Among mallard ducklings produced in the 

 2nd year of the study in which hens were fed a 

 control diet or a diet that contained 0.5 or 

 3 ppm mercury (dry weight), the findings were 

 similar (Heinz 1976a). There were no signifi- 

 cant differences among controls and groups 

 fed mercury in approach responses toward a 

 recorded maternal call and ducklings from 

 mercury-treated parents were hyper-respon- 

 sive compared with controls in avoidance 

 behavior. 



In the second generation, there were no sig- 

 nificant differences between controls and 

 ducklings from parents fed 0.5 ppm mercury 

 in approach responses to tape-recorded 

 maternal calls, in avoidance of a frightening 

 stimulus, or in open-field behavior (Heinz 

 1976c). 



Plastic and Other Artifacts 



Small plastic beads and irregularly shaped 

 particles up to 0.5 cm in diameter are com- 

 monly found in plankton samples from widely 

 separated oceanic areas, including the north- 

 western Atlantic, Sargasso Sea, Bristol 

 Channel (United Kingdom), and the coastal 

 waters of southern New England (Carpenter 

 and Smith 1972; Carpenter et al. 1972; Morris 

 and Hamilton 1974; Colton et al. 1974). The 

 particles are primarily composed of polysty- 

 rene or polyethylene compounds and have 

 about the same density as seawater. Their 

 various colors include white, green, brown, 

 blue, red, or clear (Carpenter and Smith 1972; 

 Morris and Hamilton 1974; Colton et al. 

 1974). The polystyrene spherules evidently 

 are of industrial origin, because they have 

 been found in the effluents from manufacture 

 of polystyrene (Hayes and Cormons 1974; 

 Morris and Hamilton 1974). Their abundance 

 in the British Channel water was lowest near 

 the seaward end and greatest in the inner part 

 of the Channel, near the Holm Islands. Ben- 

 thic sediments near the Holm Islands con- 

 tained as many as 20,000 beads/m 2 (Morris 

 and Hamilton 1974). 



Small fish ingest the beads and particles 

 (Carpenter et al. 1972; Kartar et al. 1973). 



