404 



REPORT DOCUf/,[-JTATIOf. PACE 



The Georges Bank Benthic Infauna Monitoring Program 



April 29, 1983 



James A. Blake, J. Frederick Grassle, 

 Nancy Maciolek-Blake, Jerry M. Neff, Howard L. Sanders 



8. Performing Or| 



Performing Org»nlijtlon Name and Addreai 



Battelle New England Marine Research Laboratory 

 397 Washington Street, Duxbury, MA 02332 

 Woods Hole Oceanographic Institution 

 Woods Hole, MA 02543 



U.S. Department of the Interior 



Minerals Management Service, Procurement Division 



Procurement Operations Branch B, Mail Stop 635 



12203 Sunrise Valley Drive 



Reston, VA 22091 



14-12-0001-29192 



13. Type of Riport 



EXECUTlVt; SUMMARY 



*hsrraet Concems about the potential effects of oil and gas exploration activities on 

 the highly productive Georges Bank off the coast of Massachusetts led to the initiation 

 of an intensive monitoring program in July, 1981. The program includes intensive samp- 

 ling of the benthic communities, collected near, upcurrent and downcurrent of the drilling 

 rigs, analysis of bottom photographs for epifauna and microtopography , dredge and trawl 

 collections, CHN and sediment grain size analysis. Collections of six replicate infaunal 

 samples at each of 46 stations are made on a seasonal basis. Samples are collected with 

 a 0.04m2 modified Van Veen grab sampler and are double live-sieved through 500 gm and 

 300 ym screens. Twenty-nine stations are positioned in a tight radial array around 1 rig 

 at 80 m. A second group of 3 stations are near a rig site at 145 m. The remaining sta- 

 tions cover a broad expanse of the Bank and nearby areas of potential deposition of 

 drilling materials. Use of the 300 um screen has resulted in the retention of newly 

 settled and juvenile forms, as well as small-bodied species which are normally under- 

 sampled by larger screens. The capability of identifying the earliest juvenile stages 

 □f several species has enabled us to provide accurate counts of each species and to 

 predict times of settlement. Results from the first 4 biological collections indicate 

 little heterogeneity within stations, with good replication between samples. A strong 

 relationship between faunal composition and both sediment type and depth is indicated by 

 cluster analysis. No biological impacts which could be attributed to drilling activities 

 have been detected to date at any station, including the site-specific array in Block 312, 

 the 3 stations near the drill rig in Block 410, or any regional station monitored in 

 this program. 



Georges Bank, benthic infauna, exploratory drilling, 

 drilling fluids 



Availability unlimited 



21. Bo. of 



