trapped inside. The bottom portion of the silt was black indicating that 

 sulfate-reducing bacteria were present in the mud and had produced hydro- 

 gen sulfide. Although a seawater sample was not obtained for dissolved 

 oxygen analysis, the production of hydrogen sulfide by the bacteria had no 

 doubt occurred in an anaerobic environment; therefore, it can be assumed 

 that there was very little oxygen present inside the fine nylon-screen-covered 

 cylinders toward the latter part of the test. In this environment, only calcar- 

 eous tubeworms were found growing on the test panels and other species of 

 fouling organisms were absent. 



Figure 32. Marine growths and corrosion formed over test panels exposed for 



92 days in different ways. Left to right: in control chamber, nylon- 

 screen-covered chamber, uncovered chamber, and on plastic strip. 



31 



