intestinal mucosa (various authors in Ohlendorf et al. 1978); 



(2) A low mortality (under unstressed conditions) was found in adult Mal- 

 lards fed small amounts of oil; ducklings were more adversely affected 

 (Stickel and Dieter 1979); 



(3) Mallard hens laid half as many eggs as usual when fed diets containing 

 2.5% South Louisiana crude oil (Eastin and Hoffman 1978, Stickel and 

 Dieter 1979); 



(4) Ducklings fed 5% South Louisiana crude oil grew more poorly than con- 

 trols, did not develop normal flight feathers, and exhibited liver hy- 

 pertrophy and splenic atrophy (Eastin and Hoffman 1978). 



Oil, even in miniscule amounts, will severely reduce the hatching success 

 of duck, heron, gull, and tern eggs (Eastin and Hoffman 1978, Stickel and Dieter 

 1979). As little as 5 microliters of oil reduced hatching of Mallard eggs, by 

 26% (for Prudhoe Bay crude oil) to 90% (for South Louisiana crude oil; Stickel 

 and Dieter 1979). Toxicity of these and other oils is greater for newer eggs 

 than for those further along in incubation, and older, weathered oils are less 

 toxic than fresh ones. Experimental oiling of the plumage of incubating gulls 

 causes significant egg mortality when the oiled feathers come in contact with 

 the eggs. Oiling of eggs also results in a significant number of deformed 

 chicks: deformed bills, incompletely ossified wing or foot bones, abnormally 

 small liver lobes, and stunting were the most common abnormalities found in 

 these experimental studies (Stickel and Dieter 1979). 



POTENTIAL HAZARDS TO MARINE BIRDS FROM OFFSHORE OIL PRODUCTION 



About two-thirds of the oil in coastal waters is derived from runoff and 

 effluent from terrestrial sources. Tanker operations account for about 26 times 

 as much oil in marine waters of the United States as do offshore operations 

 (Ohlendorf et al. 1978), but may account for a disproportionately large share 

 of avian mortality to oil. Ohlendorf et al . (1978) suggested that, for the 

 marine environment, it may be safer to produce oil offshore than to import it. 

 It seems likely, however, that onshore habitat change and loss resulting from 

 the development of facilities related to offshore oil production will, in the 

 long run, have a more adverse effect on the waterbirds of the southeastern 

 United States than will oil production itself. 



Longley and Jackson (1980) reviewed this problem for brackish marsh areas. 

 They summarized activities related to oil production and their effects on the 

 environment and suggested ameliorative measures that may be taken. Effects in- 

 clude direct loss of vegetation and animals (e.g., by dredging, construction of 

 pipelines and roads); addition of dissolved, particulate, and toxic materials 

 to the environment; and changes in water flows. The authors considered changes 

 in water flow the most damaging hazard, one that may result in complete conver- 

 sion of a marsh ecosystem. Such an event could be accompanied by a reduction 

 or elimination of the populations of marine birds that use the habitat for nest- 

 ing or feeding. 



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