to energy sources other than acetate or HL (such as methylamines) , and 

 sulfate reduction dominates as the significant terminal process (Win- 

 frey and Ward, submitted). As another major objective of this study we 

 examined terminal processes of the anaerobic food chain, which should 

 indicate the activity of the overall food chain, for evidence of 

 changes due to AMOCO CADIZ oiling. The processes investigated were 

 those which dominated the food chains, principally sulfate reduction 

 and acetate metabolism. 



METHODS 



Location of Sampling Sites 



Sites were selected to represent beach, estuary and salt marsh 

 sediments in the lower intertidal region which were significantly oiled 

 by AMOCO CADIZ pollutants. Similar sites in areas unoiled or lightly 

 polluted were selected as controls. Locations are shown in Figure 2. 

 Observations on the chronology of oil movements were used to determine 

 the extent of oil impact and times at which oiling first occurred 

 (Centre National pour 1 'Exploitation des Oceans, 1979; Gundlach and 

 Hayes, 1978). The oiled beach site was between stations B and C at 

 AMC-4 (Gundlach and Hayes, 1978). This site was opposite the wreck and 

 was heavily oiled immediately after the spill. The control beach site 

 was 100 m east of the west access to the beach at Trez-hir. This beach 

 faces the Bay of Brest and was not reported to have been oiled. The 

 oiled estuary site was a mudflat at Aber Wrac'h, 200 m south of the 

 stone wall at EPA-7 (Calder, et al., 1978). AMOCO CADIZ oil was de- 

 tected in this area in medium thickness two days after the oil spill. 

 The control estuary site was a mudflat on the south bank of Aber Ildut 

 approximately 3 km west of Breles. Oiling at this site was prevented 

 by two booms extended across the mouth of the Aber. The oiled marsh 

 site was an intertidal mudflat in lie Grande near AMC-18 (Gundlach and 

 Hayes, 1978). Thick accumulations of AMOCO CADIZ oil reached this site 

 by 'the eighth day following the spill. The control marsh was a natural 

 mudflat in the lie Grande marsh, just south of the main intertidal 

 channel. A barricade at the bridge adjoining east and west marsh areas 

 prevented oiling at this site. 



Sample Collection and Processing 



Sediment cores were collected with hand- pushed plexiglass tubes 

 (60 cm x 37 mm ID), stoppered, and transferred to the lab in an upright 

 position. Cores for sediment hydrocarbon analysis were kept frozen 

 until processing. Processing of samples for biological activities was 

 done at the Centre Oceanologique de Bretagne in Brest or at the Station 

 Biologique at Roscoff within 8 h after collection. All manipulations 

 for analysis of biological activity were carried out using strict an- 



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