ECOLOGICAL AND PHYSIOLOGICAL/TOXICOLOGICAL EFFECTS 

 OF PETROLEUM ON AQUATIC BIRDS 



INTRODUCTION 



Oil and gas development and exploration in 

 marine coastal areas and the Great Lakes will 

 result in unavoidable spills of polluting oil. 

 Although large oil spills may kill thousands of 

 birds and stimulate much public concern, the 

 bulk of oil that reaches aquatic environments is 

 released in the course of normal operations, 

 with a total input into the world's oceans esti- 

 mated at 6 million metric tons per year. The 

 effects of sublethal low-level oil pollution may 

 be more deleterious to bird populations over 

 the long term than the spectacular bird kills 

 resulting from oil spills. 



The physiological and ecological effects of 

 oil on waterbirds were examined in a series of 

 laboratory and field experiments, including 

 studies of the effects of oiling on hatchability 

 of eggs; the effects of an oil-contaminated diet 

 on physiological condition, reproduction, and 

 survival; and the accumulation of oil in body 

 tissues. Chemical methodology was developed 

 in support of these studies. 



EFFECTS OF OILING ON HATCHABILITY 

 OF EGGS 



Very small quantities of oil applied to 

 aquatic bird eggs in the laboratory caused 

 embryo mortality (fig. 1). As little as 5 jul 

 (about one drop) of South Louisiana crude oil, 

 No. 2 fuel oil, Kuwait crude oil, Bunker C fuel 

 oil, or Prudhoe Bay crude oil applied to the 

 shell surface on the eighth day of incubation 

 reduced hatching of mallard eggs by 90%, 70%, 

 68%, 62%, and 26%, respectively. No embryos 

 survived application of 50 nl of any of the 

 tested oils. Fifty microliters of oil represented 

 approximately 1 ppm of the egg. 



When 50/il of an alkane mixture of com- 

 pounds naturally occurring in crude oils 

 (paraffins) or propylene glycol was applied to 

 the shell surface, embryo mortality did not 

 occur even though the shell surface was coated. 

 This indicated that some other component of 

 the oil was affecting the embryos, and that 

 they were not dying because of oxygen depriv- 

 ation caused by clogged shell pores. 



The toxicity of various oils to embryos is 

 not confined to mallards. Common eider, great 

 black-backed gull, laughing gull, Louisiana 

 heron, and Sandwich tern eggs were oiled arti- 

 ficially both in the field and the laboratory. 

 Variations in toxicity from that demonstrated 

 for mallards can be attributed to differences in 

 embryo size, which change the dose-to-weight 

 relationship, and differences in ages of embryos 

 at treatment (younger embryos are more 

 sensitive). As an example, mortality was 26% in 

 16 clutches of naturally incubated common 

 eiders treated in the nest with 20 jul of No. 2 

 fuel oil and opened 7 days after treatment 

 (table 1). Mortality was 60% among 25 clutches 

 of great black-backed gulls (table 2). Embryos 

 of both species are approximately twice the 

 size of mallard embryos and those tested were 

 of mixed ages at the time of treatment. Morta- 

 lity of 8-day-old mallard embryos treated with 

 20 /il of No. 2 fuel oil and artificially incubated 

 was 100%. 



Thirty clutches of great black-backed gulls 

 treated with 20 *d of fuel oil were incubated to 

 term by the parents on the Isles of Shoals, 

 Maine. Hatching success was again one-half that 

 of controls and production of fledglings was 

 one-third that of controls. External environ- 

 mental factors did not appreciably modify the 

 toxic effects of the oil in this or other field 

 studies. 



No. 2 fuel oil and Prudhoe Bay crude oil 

 were weathered over water in outdoor troughs 

 at the Patuxent Center. After 2 weeks of 



