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Dr. Bolton. Trays containing different concentrations of drilling 

 fluid are placed on the ocean bottom. A fine layer, I think about 2 

 millimeters, on that mud tray will change the structure of the 

 community that settles there. So the change in community struc- 

 ture is an impact. Fish often feed on these benthic organisms. 



Mr. Wyatt. In and around the area? 



Dr. Bolton. These were done off of Pensacola, I believe, on 

 EPA's Stage I. So it is a field study but it was not done at the 

 Flower Gardens. It was simply done with drilling muds that are 

 used in the Gulf of Mexico. 



Mr. Wyatt. That would be during the time of drilling? 



Dr. Bolton. These were muds taken off of drilling rigs during 

 operations and then layered or mixed with azenic muds on trays 

 which were set out along with control trays and larval organisms 

 were allowed to settle on those trays. The control trays were com- 

 pared with the experimental trays. The results indicated that, yes, 

 the benthic community was affected. 



Mr. Wyatt. For what length of time? 



Dr. Bolton. It was the length of the larval settling. I am not 

 sure what the period of time used was. It was long enough to get a 

 crop of larval organisms. 



Mr. Wyatt. Which would lead us to believe that there is a 

 reduction 



Dr. Bolton. That there is some change, certainly, in the Benthic 

 community as a result of the presence of drilling fluids. 



Mr. Wyatt. Can you project from that kind of a study what the 

 ultimate damage would be to the entire Gulf of Mexico or to a 

 certain portion of the Gulf of Mexico? 



Dr. Bolton. That is one of a complex of studies which will be 

 used to make that type of assessment. But all of the studies are not 

 completed. 



Mr. Wyatt. How long will it be before the studies are completed? 



Dr. Bolton. I believe our field scientists are planning to com- 

 plete the effects studies by 1982. 



Mr. Wyatt. This is being done off the coast of Florida? 



Dr. Bolton. These studies are part of a comprehensive program. 

 Part of it is being done off Florida and in the gulf area, but part of 

 it also is being done in New England in a number of marine labs. 

 A lot of the work is being done by marine researchers as contrac- 

 tors for EPA, paid for by EPA. 



Mr. Wyatt. In collecting samples do you find a greater, higher 

 residue of toxicity in the Gulf of Mexico that could be attributed to 

 drilling muds than you do in other areas? 



Dr. Bolton. You certainly find higher concentrations of some of 

 the heavy metals than you would find in many other areas. That is 

 what makes much of the field studies very difficult to interpret, 

 because the baseline of heavy metal contamination is so high. 

 Initial experimental sampling that might be considered a signifi- 

 cant increase in heavy metals concentration with a low baseline 

 would be statistically nonsignificant given the high baseline. So it 

 makes it difficult to make those interpretations in the Gulf of 

 Mexico and certainly to extrapolate to other areas. 



Mr. Wyatt. Because you start with a higher baseline of heavy 

 metals. 



