(Szaro et al . 1978; Patton and Dieter, in press; Coon and Dieter, in prepara- 

 tion; Szaro, in preparation). In several studies, tissues from dosed and un- 

 dosed ducks were chemically analyzed for oil components. 



Indoor Pen Studies 



Studies in indoor pens are advantageous because light, temperature, 

 water, food intake, and other external elements can be precisely controlled. 

 Under constant conditions, the effects on test animals of varying one or more 

 factors at a time can be examined. 



Feeding studies were conducted to determine the effects on birds of 

 ingesting different doses of crude oil in their food. In initial studies 

 with adult mallard ducks (Anas platyrhynchos) , various amounts of crude oil 

 were included in commercial duck feed. Briefly, pairs of mallards were 

 placed in separate cages and fed either clean feed or one of the several 

 diets containing crude oil at environmentally realistic values ranging from 

 0.25 to 2.5%, for 26 weeks. Those receiving oil in their diet laid fewer 

 eggs than did controls (Coon and Dieter, in preparation). In another experi- 

 ment, adult mallards compensated for oil ingestion with an increased liver 

 clearance capacity (Patton and Dieter, in press). 



Subsequent experiments have been conducted, in which ducklings were fed 

 test diets containing 0.025 to 5% oil from the day of hatching (Szaro 1978; 

 Szaro, in preparation). After studying the effects of several crude oils, an 

 experiment was done to examine the effects of various components of these 

 crude oils (Patton and Dieter, in press). Crude oils, ingested with food, 

 have retarded growth, increased liver size, increased plasma enzyme activities 

 of alanine aminotransferase and ornithine carbamyl transferase (indicative 

 of liver and kidney damage), and decreased spleen size and hematocrit in 

 ducklings (Szaro et al . 1978; Szaro, in preparation). 



Chemical analyses of these ducks showed that ingested oil components 

 had been absorbed and could be found accumulated to a greater extent in fat 

 than in liver, kidney, and several other tissues (Lawler et al . 1978; Lawler, 

 Loong, and Laseter, 1978^, 1978b). 



Indirect ingestion of oil may occur through the food chain. This hypo- 

 thesis was tested using a radioactive isotope. Previous studies had strongly 

 implicated the aromatic hydrocarbon fraction of crude and No. 2 fuel (diesel 

 fuel) oils as being most toxic. When crude oil is mixed with water, these 

 aromatic fractions are found in the water-soluble fraction (WSF). A volume 

 of No. 2 fuel oil was poured onto water (5% oil by volume) to simulate an oil 

 spill. This mixture was stirred for 20 hours. No. 2 fuel oil contains 

 approximately 16% napthalenes and about 40% total aromatics. The aqueous 

 phase containing the WSF was decanted, and a known activity of ^c-naphthalene 

 was added. Crayfish were placed in the WSF for 3 hours and then fed to adult 

 ducks. The WSF, the crayfish, and the duck tissues were measured for radio- 

 activity. Knowledge of the activity of l^C-naphthalene that was added and 

 the amount of aromatics or naphthalene in the WSF allowed calculation of the 



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