Oil Spill Effects 395 



TABLE 9-2 A verage Bacterial Numbers and Turnover Times for Acetate in 

 the Plankton and Benthic Respiration in Ponds B, C and E 



* 1971 

 **1972 



The loss rate of Prudhoe crude (10% in the first day) is much less than 

 that measured by Snow and Rosenberg (1975a) who found that 34 to 43% 

 of Canadian crude oil was lost in the first day. Our results are similar to 

 those of Atlas (1975) who also worked with Prudhoe crude. Thus it is 

 important to realize that oil from different sources will weather in different 

 ways. Also, the amount of oil that will actually dissolve in water will differ 

 for different sources. Federle et al. (1979) reported that Barrow pond 

 water took up 15 mg oil liter " ' after 2 hours irrespective of the amounts of 

 added oil. At 8°C, vigorous shaking resulted in 90 to 125 mg oil liter "'in 

 solution. The water soluble fraction is the most lethal part of the oil. 



BIOLOGICAL MEASUREMENTS 



Bacteria 



One year after the oil spill in Pond E, the bacterial activity in the 

 plankton was higher than that in control ponds but total numbers of 

 bacteria were unchanged. Activity, as measured by the turnover time of 

 '■* C-acetate (Wright and Hobbie 1 966), was most rapid in Pond E (Table 9- 

 2). Bacterial numbers were within the range of the controls. However, the 

 direct count method enumerates all bacteria and we know that only a 

 small fraction of these are active. These active forms could have increased 

 in Pond E without any measurable change in direct counts. 



Two years after the oil spill, the sediment respiration (one date) was 

 less than half that of the controls (Table 9-2). 



Bergstein and Vestal (1978) used plate-count techniques to enumerate 

 the types of bacteria in the water and sediment in oiled and unoiled 

 portions of Pond Omega, 2 years after the spill. There were no differences 

 in the numbers of bacteria that could grow on crude oil, nutrient agar, 

 mineral salts agar, or hexadecane between oiled and unoiled areas of the 

 pond. If there was a toxic or stimulatory effect on the microflora after the 

 spill, the microflora were back to the control-pond levels within 2 years. 



