3. Behavior and Effects of Spilled Oil . Spilled oil tends to 

 spread out after release, forming oil several millimeters thick at the 



center of the spill and forming a very thin film near the perimeter. 



5 

 These slicks are readily driven by wind and water currents. The oil 



is distributed into the atmosphere through evaporation of the lighter 

 fractions, mixed into the water column, and absorbed into bottom sedi- 

 mentation. The 1969 Santa Barbara oil spill occurred during a period 

 of heavy rainfall. The turbid river water mixed much of the oil with 

 bottom sediments of the Channel where its effect may be relatively 

 long-lived. 



Although biological degradation of spilled oil begins almost 

 immediately, the toxicity of oil when it reaches onshore habitats 

 depends upon a number of factors. These follow: the size, location, 

 and season of the spill; the chemical and physical characteristics 

 of the oil; the period of time that the slick floats on the surface; 

 wind and wave action; the sediment load of nearshore waters at time of 

 the spill, and the methods used to contain or clean the spill. Because 

 of these factors, the effects of an oil spill can vary widely making it 

 very difficult to predict the impacts. 



o 



Crude oil may harm organisms in several ways. Oil, or its water- 

 soluble toxic components may kill directly. Organisms, or their 

 offspring, may also be harmed through contact with carcinogenic or 

 mutagenic compounds. Effects on an animal's behavior may include 

 alteration of responses to predators and responses to sexual stimuli. 

 Organisms may also be harmed indirectly through a reduction in their 

 resistance to diseases. 



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