oil-polluted Abers and from nearby reference stations. These may 

 be useful indices of pollutant stress. They include blood cholesterol/ 

 HDL cholesterol, liver ascorbic acid, and skeletal muscle-free amino 

 acid ratios in fish; and adductor muscle-free amino acid ratios in 

 oysters. Blood glucose also has potential as an index of stress in fish, 

 if the fish can be captured and blood samples taken very quickly. 

 Alternatively, useful information can be obtained if degree and duration 

 of capture- induced stress can be standardized for reference and experi- 

 mental fish. In such a case, the index of chronic pollutant stress is 

 hypoglycemia, reflecting a loss or diminuation of the capacity of the 

 hypophyseal-interrenal system to respond to stress. 



Several of the alterations in biochemical parameters in oil-polluted 

 fish and oysters are indicative or symptomatic of poor nutritional status 

 (e.g., depressed muscle glycine, depletion of liver glycogen and ascor- 

 bate, etc.). This may be related to histopathological lesions, reported 

 by Haensly and Neff in this publication in the gut and liver of plaice 

 from the oil-contamianted Abers. 



One difficulty in using biochemical and histopathological parameters 

 as indices of pollutant stress is that one is not always certain that 

 animals from the impacted and reference sites are from the same popula- 

 tion and therefore can be compared biochemically and histopathologically. 

 The only way to establish convincingly that differences observed in indi- 

 cator parameters in reference and impacted populations are due solely or 

 primarily to the pollution incident under investigation, is to have 

 comparative data collected before the pollution incident. This usually 

 is not available. The oysters used in this investigation are a recently 

 introduced species Crassostrea gigas and are from a common breeding 

 stock throughout Brittany. Genetic differences between reference oysters 

 and oysters from the Abers are therefore extremely unlikely. However, 

 the extent to which plaice from the west and south coast of Brittany 

 (reference sites) mix and interbreed with plaice from the northwest 

 coast (site of the Abers) is not known. Some intermixing undoubtedly 

 occurs. It seems likely, therefore, that many of the differences we 

 have reported between oysters and plaice from the Abers and those from 

 reference stations are attributable directly or indirectly to impacts 

 of the Amooo Cadiz oil spill. 



There has been substantial improvement in condition of oysters 

 and plaice in the Abers during the timecourse of this investigation 

 (up to 27 months after the spill). Recovery is still not complete, 

 however . 



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