Table 1. Effects of No. 2 fuel oil on embyos of the 

 common eider (Albers and Szaro 1978). 



% of clutch alive 



No. Mean Mean of 



. of % clutch transformed Mean 

 Treatment Nests eggs alive size percentages 2 % ' 



Control 13 60 98 4.6 75.42 93.7 



No. 2 fuel 



oil (5m0 19 84 94 4.4 72.54 91.0 



No. 2 fuel 



oil (20 Ail) 16 72 74 4.5 59.40 74.1 



Three nests were found; 9 nests were abandoned or des- 

 troyed by predation. 



2 

 Arcsine transformation for binomial proportions; angle 



equals arcsine \J percentage. Significant one-way analysis 

 of variance, P <0.05; 20 jul group significantly dif- 

 ferent from control group, f-test, / > <0.025. 



^Mean of transformed percentages converted back to 

 percent. 



Table 2. Embryo survival in naturally incubated great 



black-backed gull eggs 8 days after treatment with 



No. 2 fuel oil (Coon et al. 1979). 



Condition of 

 embryo 



No. of Survival No. of % 



Treatment clutches Index eggs Alive Dead alive 



Control 28 95.8 81 72 9 88.9 



No. 2 fuel 



oil (5 Ml) 26 90.3 72 58 14 80.6 



No. 2 fuel 



oil (20 mD 25 32.7' 72 29 43 40.3 



Most clutches contained three eggs; however, some 

 contained only two at the time of treatment. For each 

 clutch, a percentage of the total embryos alive 8 days 

 after treatment was computed. Clutch survival data 

 were evaluated statistically after angular transforma- 

 tion, arcsin\/X. This transformation is applicable to 

 binomial data expressed as percentages and covering a 

 wide range of values (Steel and Torrie 1960). The Sur- 

 vival Index reported can be described by the following 

 expression: [sin (l/n£arcsin\/%)] 2 and is a transforma- 

 tion back to the original scale. Statistical comparisons 

 were made on the transformed scale, rather than on the 

 reported values. 



'Significantly different from control, P<0.05 (Stu- 

 dent's r test). 



weathering, No. 2 fuel oil was significantly less 

 toxic than fresh oil when applied to mallard 

 eggs. Prudhoe Bay crude oil was less toxic than 



its fresh counterpart after 3 weeks of weath- 

 ering. Even after the oils weathered 4 weeks, 

 however, 20 ix\ of each still caused 50% morta- 

 lity when applied to mallard eggs (fig. 2). 



The minute quantities of oil that produce 

 marked reductions in embryonic survival sug- 

 gest that oil pollution could seriously affect 

 marine and estuarine bird populations by trans- 

 fer of oil from the plumage of incubating birds 

 to their eggs. Laughing gulls were captured at 

 their nest sites in Texas to examine this possi- 

 bility. Forty-two were treated with 2.5 ml of 

 No. 2 fuel oil applied with a syringe to the 

 feathers over and surrounding their brood 

 patches. Twenty additional birds were treated 

 with water. All were released immediately after 

 treatment. After 5 days, their eggs were col- 

 lected and examined. Embryo mortality was 

 41% in the eggs incubated by the oiled gulls , 

 but only 2% in those incubated by the water- 

 treated gulls (table 3). 



Paired mallards were kept in pens con- 

 taining water troughs in which they could swim 

 during the breeding season. Prudhoe Bay crude 

 oil was added to the water during the first 

 week of incubation. One-third of the troughs 

 were treated with 100 ml of oil per square 

 meter of surface area, another one-third were 

 treated with 5 ml of oil per square meter, and 

 the last group were left untreated. Hatching 

 success was 45%, 85%, and 95% respectively. 



Other indications of toxicity include tera- 

 togenic effects (production of malformed indi- 

 viduals) when oil is applied to eggs during the 

 first few days of embryo development. Treat- 

 ment of mallard eggs at 24 hr of development 

 with 5 /il of crude oil produced a significant 

 number of abnormal survivors (table 4). The 

 most common abnormalities included de- 

 formed bills, incomplete ossification of the 

 wing or foot bones, reduction in size of the 

 liver lobes, and stunting. Teratogenicity was 

 increased when vanadium, nickel and mercury, 

 metals normally found in petroleum, were 

 added. 



Mortality was greater when artificially 

 formulated mixtures of aromatic compounds 

 were applied to the egg surface than in controls 



