■ What controls settling success in benthic communities? What are the 

 cues in settling? Are they physical? Are they chemical? What 

 concentrations of what contaminant may interfere with the cues? 



■ Are there different impacts at different life stages for the same 

 organism? 



■ What are short-term impacts vs. long term impacts? 



Teal expressed the opinion that very often it takes at least a 10 percent 

 change in the physical environment before an animal perceives it. Offering a 

 very conservative opinion, he suggested that a 1 percent change in an 

 environmental parameter to which animals are particularly sensitive would have 

 no impact on an organism or a community. If the parameter starts at a value 

 well below that to which the animal is sensitive, a much larger change would 

 have no effect. 



Cooper asked what specifically were the real dangers of drilling? Are 

 direct impacts such as suffocation by cuttings and drilling mud adjacent to 

 rigs more important or of greater concern than (as an example) impacts related 

 to the uptake of heavy metals? Ayers suggested that immediate impacts are 

 restricted to within a few hundred meters of the drill site and no significant 

 heavy metal impact has ever been seen. Most drilling mud metals are very 

 insoluble and the only ones present in concentrations significantly higher 

 than concentrations found in marine sediments are barium and sometimes 

 chromium. There is no evidence to suggest that barium, when present as barium 

 sulfate as it is in drilling mud, is a "bad actor" when introduced to healthy 

 marine populations. Ayers stressed that barium (as barium sulfate) is the 

 only drilling-mud component that is elevated in the sediments at distances 

 greater than a few hundred meters from the well site. 



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