approximately 1/4 mile from the wreck on December 23, and their film supports 

 this finding. Since the currents at the wreck site are primarily tidal, the 

 oil had passed over the spot checked by the divers twice a day for 7 days 

 prior to the dive. Microscopic examination of 25 sediment samples from the 

 Delaware II cruises also indicated the absence of visible oil. Thin-layer 

 chromatographic analyses of sediment samples have Indicated very low petro- 

 leum hydrocarbon (PHC) levels with the majority of the samples exhibiting 

 less than 1 part per million PHC's. Sediment samples from the Oceanus 

 cruises indicated appreciable levels, up to 5 ppm, of PHC's. The highest 

 levels were found at Oceanus stations 1 and 5 which are located to the west 

 of Nantucket Shoals in an area of mud bottom. The oil slick was never within 

 20 miles of these stations. Additional analytical work confirmed that the 

 oil in these samples is not from the Argo Merehant. 



Preliminary evidence indicates that oil from the Avgo Merchant is being 

 cycled through the food web of the Nantucket Shoals ecosystem. Large numbers 

 of zooplankters which are an important food of larval and adult fish are 

 contaminated with oil. The presence of petroleum hydrocarbons in zooplankton 

 indicates that an important pathway between plankton, necton, and benthos is 

 contaminated. The oil can be concentrated in the tissues of shellfish as 

 they feed on fecal pellets of the zooplankton. The significance of the 

 cycling of the Argo Merchant oil through the food web has not been fully 

 assessed and will be the subject of additional survey and experimental 

 efforts. 



Oil was found in the bottom sediments near the bow section on February 

 11, 1977. The area where the bow section dragged is contaminated with Argo 

 Merchant oil, presumably from physical contact with the bow section. The 

 area encompassed by this contamination is not known at present, but resus- 

 pension of oiled sediments in the area appears to be transporting the oil to 

 the southwest. Another Endeavor cruise was conducted February 21-25 to 

 establish the magnitude and extent of the oil contamination around the wreck- 

 age itself. 



"Tar balls" reported washing ashore on southwest Nantucket Island in 

 March appeared to have come from a recent spill, and analysis is under way 

 to determine whether the tar comes from crude or refined petroleum. However, 

 this will not be able to establish whether the tar originated with oil 

 spilled by the Argo Merchant or with another spill of No. 6 fuel oil. 



5.3 Biological Effects 



Although it is difficult at this time to assess the possible damage to 

 the Georges Bank-Nantucket Shoals ecosystem, some evidence has been found of 

 oil contaminating several species of fish, shellfish, and plankton in the 

 area of the oil spill. 



Mortalities were observed in developing cod and pollock embryos in eggs 

 collected from the area. Greatest damage was observed in eggs collected 

 closest to the Avgo Merchant, and genetic damage was greater in pollock eggs 

 than cod eggs. In one sample taken near the spill, 98 percent of the pollock 

 eggs sampled were dead or moribund, as against 64 percent of the cod eggs in 



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