406 



1. CONCLUSIONS 



• The Regional Stations analyzed for benthic infauna group consistently over 

 all four sampling periods by depth and sediment type. Replicate samples at each station 

 show an exceptionally high degree of homogeneity. Cluster analysis demonstrates that all 

 of the replicates of any one regional station are more similar to each other than to 

 replicates from any other station. When replicates at each station are summed, the 

 samples from each of the four sampling periods fuse before any separation occurs between 

 stations. This homogeneity should enable us to detect biological changes should they 

 occur at these stations. 



• Site-specific stations in the array around Station 5-1 have a homogeneous 

 community structure, both spatially and temporally over most of the area. The species 

 composition does change with the increase in the proportion of fine sand at stations 

 located k and 6 km to the west of Station 5-1. 



• At all stations sampled, the community structure (i.e., species composition) 

 does not change very much with season. Although average densities of several species 

 were observed to fluctuate seasonally, these changes probably reflect natural cycles in 

 these populations and do not appear to be related to drilling activities. 



• The only result of the chemical analyses that provides a basis for an 

 hypothesis of an impact due to drilling activities is the gradient of barium concentrations 

 (as a marker of accumulation of drilling muds) near the Block fflO Stations 16, 17 and 18, 

 and Site-Specific Station 5-1. 



• Drilling began in Block kiO in July, 1981 and continued until March, 1982. 

 With the methods of analysis used thus far, no biological impacts which could be 

 attributed to drilling activities were detected. Differences between stations were always 



greater than temporal differences at any one of the three stations. 



• Drilling began in Block 312 on December 8, 1981 and continued until June, 

 1982. At the site-specific array of stations in this block, the separation of February (M3) 

 and May (M^j) samples into discrete clusters may be a result of the decline in total 

 densities at many of the stations in February (M3), followed by a recovery in May {Mk). 



