377 



given isobath. Also, recirculation in the Georges Bank gyre 

 occurs in water depths less than 60 meters. Therefore, 

 recirculated discharge material which could possibly contciminate 

 the upcurrent control sites should be dilute, and amy effects 

 should be relatively small in comparison to downcurrent stations. 



By monitoring combinations of upcurrent and downcurrent stations 

 along more than one isobath it should be possible to compare the 

 effects of drilling activities on different benthic communities. 



Additional long-term regional stations are located in the 

 immediate Georges Bank lease sale area along Transect II 

 (stations 4, 5, and 6); at a single station within the 60-meter 

 isobath on Georges Bank where maximum resuspension of sediments 

 is likely to occur (station 15); and at sites of active deposition 

 where fine-grained materials associated with drilling operations 

 may accumulate. The latter stations are located at the heads of 

 Lydonia and Oceanographer Canyons (stations 7 and 9), at the 

 shelf /slope break (station 8), in Great South Channel (station 

 14), and at the "mud patch" (station 13). 



Sampling at all long-term regional stations includes: 

 (1) "infaunal grab samples" for characterization of infaunal 

 community structure and composition, sediment grain size 

 distribution, and organic carbon, hydrogen, and nitrogen 

 concentrations in sediments; (2) "geology and geochemistry 

 grab ssimples" for characterizing sediment grain size 

 distribution and concentrations of hydrocarbons and trace 

 metals in sediments; (3) photographs of the bottom for 

 characterizing large-scale topography and epifaunal 

 community structure and composition; and (4) measurements 

 of dissolved oxygen, salinity, and water temperature. Dredge 

 or trawl collections of epifauna will be taken at the 

 "mud patch," the head of Lydonia Canyon, and at station 2 

 (control) for. the identification of epifaunal voucher 

 specimens and the analysis of hydrocarbons and trace metals 

 in epifaunal tissues. 



Site-specific stations are eirrayed around an exploratory 

 drilling rig. The array of stations is presently located at a 

 rig site in the vicinity of long-term, regional station 5 on 

 Block 312 (Figure 2). These stations were established to determine 

 local changes in sediment texture and chemistry and in the benthic 

 communities in the immediate vicinity of drilling activity. Lease 

 block 312 was selected for this experiment because available water 

 current and sediment transport observations suggest that 

 drilling discharges may be most easily observed in the 75 to 

 95 meter depth range along the southern flank of Georges Bank. 



Sampling within the site-specific array is being conducted 

 within approximately six kilometers of the rig. An over- 

 sampling approach is being used, with stations finely spaced 

 in a quasi-radial pattern around the rig. More intensive 

 sampling is conducted within two kilometers of the rig 



28-914 0—84 25 



