Symbiotic bacteria were separated from mussel gill 

 tissue through a series of filtration steps and assayed for 

 hydrocarbon metabolizing activity. Initial results from 

 these experiments indicate that the bacteria and not the 

 gill tissue are responsible for the observed hydrocarbon 

 metabolites. Preliminary results from inhibitor studies 

 have shown that metabolite production is inhibited by use of 

 MFO inhibitors. Some aromatic hydrocarbons are co-oxidized 

 by bacteria during the oxidation of methane; however, the 

 aromatic hydrocarbon metabolite inhibition data using a 

 methane mono-oxygenase inhibitor is inconclusive in this 

 study. 



Mussels and sediment were collected from a variety of 

 sites of varying levels of petroleum seepage, and preserved 

 for hydrocarbon analysis. Hydrocarbon loads in the mussels 

 appear to be variable with respect to location and tissue, 

 as would be expected for animals living over a wide range of 

 hydrocarbon exposure levels. Some mussels have exhibited 

 significantly higher hydrocarbon levels in the gills, 

 particularly in the naphthalene range, than in the rest of 

 the body while in others a more even distribution of 

 polynuclear aromatic hydrocarbons ( PAHs ) was observed (Table 5) 



Various species were also assayed for the presence of 

 oxygen detoxif icatory enzymes, catalase and superoxide 

 dismutase (Table 6). Again mussels exhibited significantly 

 higher activities than clams, gastropods or tube worms. 

 Methane oxidation probably produces oxygen radicals. All 

 catalases were inhibited by 3-amino-l, 2, 4-triazole 

 indicating that they are normal catalases (some sulfur 

 dependent metazoans have a modified catalase not inhibited 

 by 3-amino-l, 2, 4-triazole ) . 



Taphof acies Analysis 



The first year of submersible activity at the petroleum 

 seep sites have helped to address several major avenues of 

 investigation. A higher shell accumulation rate at seep 

 locations compared with continental shelf localities has 

 been documented. Shells clearly accumulate at seeps in 

 greater quantities than at any other shelf, slope or bay 

 site in the western Gulf, except oyster reefs. Only here 

 are shell beds formed that are not "event" deposits. 

 Coupled with the large accumulation of shell material is an 

 apparently high dissolution rate which indicates that net 

 productivity (calcium carbonate accumulation) is greater 

 than shell loss in spite of the acidic environment. Clearly 

 mussels are rarely preserved. Hence, fossil analogues 

 should be dominated by clams. Indeed that is the case at 

 Tepee Buttes. It is known that mussel shells are poorly 

 preserved at all locations. The question is: "Why are 



131 



