The sulfate reducers are anaerobic bacteria which obtain their energy by the 

 reduction of sulfate and sulfites in water in the absence of free oxygen. 

 The end product of their metabolic process is hydrogen sulfide (H„S). These 

 microbes are considered to be responsible for the anaerobic corrosion of 

 metals . 



The sediment samples obtained with a scoop sampler were washed through 

 a screen to collect mud-dwelling organisms. The animals were bottled and 

 preserved in a 5-percent glycerol-alcohol solution for laboratory analysis, 



A variety of animals was found in these sediment samples. Amphipods and 

 annelids were the marine organisms collected most abundantly in the vicinity 

 of both STU test sites, 



TEST MATERIALS 



For evaluating nonmetallic test specimens to deep sea biological effects, 

 two aluminum biological test specimen racks (bio-racks) were built which 

 could be attached to a STU. Each rack could hold several plastic rods and 

 tubes each 3 feet long, and a 30- by 12- by 1/8-inch phenolic laminated 

 plastic sheet. Numerous smaller test specimens were attached to the plastic 

 sheet; one sheet was secured to ttie upper section of a bio-rack, and an 

 identical sheet was secured to the bottom. In order to expose the test 

 materials to biodeterioration in mud as well as water, the two racks were 

 attached to the STU so that the lower portions would be buried in the bottom 

 sediment and the upper portions exposed to sea water about 3 feet above the 

 mud line. 



The bio-rack specimens were carefully prepared for deep-sea exposure. 

 The 2- by 6- by 1/2-inch wood panels were cut from a sound lumber. These 

 wood panels were employed to collect any deep sea fungi ana marine borers 

 which might be present on the ocean floor. The sections of 3-foot-long 

 plastic rods, tubes, pipe, and rubber tubes were treated in different ways. 

 One section of each rod was roughened, a second section was wrapped in 

 burlap, a third section was taped with plastic and rubber electrical tape, . 

 and the fourth section was left smooth. Each such section was about 6 

 inches long. The various wrappings were to provide a favorable foothold 

 for growth of deep sea fouling and boring organisms. A length of 2- by 

 4-inch untreated pine wood was fitted around each of the 3-foot plastic 

 specimens to act as bait to attract and lead borers into direct contact 

 with each of the plastic specimens (Fig 1). 



Four different kinds of rope, such as synthetic plastic fiber rope 

 (nylon and polypropylene) and natural fiber rope (cotton and Manila), were 

 placed on the bio-racks. Electrical cables covered with rubber or plastic 

 insulation of various thicknesses V7ere also placed on the bio-racks. A 

 small pine wood piece was fitted around each electrical cable specimen to 

 act as bait to attract and lead any marine boring animals into direct contact 

 with the cable specimens. 



168 



