Based on the changes in the composition of the microbial community, 

 as evidenced by elevations in numbers of hydrocarbon utilizing 

 microorganisms and based on the microbial biodegradation potentials, it 

 can be stated that biodegradation appears to have been a very important 

 process that had the potential for significantly altering the 

 composition of the hydrocarbon mixture that impacted the sediments of 

 the Brittany Coast following the AMOCO CADIZ spill. With time the 

 residual hydrocarbon mixture should contain increasingly high 

 proportions of complexed branched and condensed-ring hydrocarbon 

 compounds that are degraded relatively slowly by the indigenous 

 microorganisms . 



The weight of the extractable hydrocarbons confirmed the occurrence 

 of contaminating hydrocarbons at site 2 in July 1980, presumably as a 

 result of the TANIO spillage (Table 9). Similarly, high concentrations 

 of hydrocarbons were found in at Sites 11 and 12 which were closer to 

 the TANIO wreck. The levels of hydrocarbons at Site 3 remained high 

 throughout the sampling program. Sites 1, 4, 9, and 10 showed a general 

 lack of significant hydrocarbon concentration that would be indicative 

 of petroleum pollution. Sites 5, 6, 7, and 8, in contrast, showed 

 somewhat elevated hydrocarbon concentrations. 



TABLE 9. Weights of extractable hydrocarbons (ug/g) . 

 Site 12-78 3-79 8-79 11-79 3-80 7-80 6-81 



3 h 



4 E' 



2 



5 ' 



2 

 6 f . 



1 i\ 



2 

 10 f 



2 



12 f l 



r 2 

 A f , - - 102 



t - - - 88 



B f , - - - 210 



f* - - - 210 



C f - 13 



f - - - 21 



D f - 21 



t\ - - 10 



11 



