407 



The density declines in February (M3) may be related to changes in sedinnent composition 

 or to normal seasonal population cycles. An analysis of the change in densities over time 

 of 2't infaunal species revealed that at Stations 5-1, 5-2 and 5-8, where the greatest 

 increment in barium concentration between 3uly (Ml) and May (.Mk) occurred, the 

 densities of many species declined in November (M2) before drilling began and increased 

 in February (M3). 



• In general, no significant changes in benthic community structure which can 

 be related to drilling activities have been detected with the methods of analysis used thus 

 far. 



2. RECOMMENDATIONS 



• Sampling should continue at all long-term Regional Stations in order to 

 establish normal seasonal patterns of population fluctuations. This will allow us to better 

 interpret population fluctuations seen at drilling areas. The most important stations 

 include the deeper water and canyon Stations 3, 6, 7 A, 8, 9 and 12 adjacent to the 

 proposed Lease Sale 52 area, and stations in major depositional areas (Stations 13 and 

 13 A). 



• Sampling should be continued at three stations in Block ^10 (Stations 16, 17, 

 18). This will provide information on long-term effects at a deeper drilling site, which 

 may be useful for predicting impacts of drilling in the Lease Sale 52 area. 



• Biological and chemical sampling should continue at those stations in the 

 Site-Specific array at which elevated concentrations of barium (a marker of drilling mud 

 accumulation) were detected in the fine fraction of sediment on Cruise M^t. First priority 

 should be given to stations of this type two or more kilometers from the drill site. 

 Analysis of sediment barium concentrations at an additional radial array of four to sixteen 

 stations located about 8 and/or 10 km from the rig site would be useful for better defining 

 the pattern and extent of movement of drilling muds away from the rig site. 



• Barium should be analyzed in the fine fraction of sediments from the 

 Secondary Site-Specific Stations for Cruises Ml through W* to better establish the 

 distribution of drilling muds in sediments around the rig site. If elevated concentrations 



