RESISTANCE OF MATERIALS TO MARINE BIOLOGICAL ATTACK 1097 



dae. Members of the same family were reported by Snoke and Richards^ 

 to have bored through the lead sheath of a submarine telephone cable. 



The bacteria generally are single-celled organisms, a large number of 

 which are heterotrophic, that attack organic matter and use it as a 

 source of carbon or energy. The bacteria play an important part in the 

 biology of the sea, their most important function being to decompose 

 organic material into carbon dioxide, water, ammonia and minerals. The 

 characteristics, distribution and function of the marine bacteria have 

 been described in great detail by ZoBell.'" Bacteria are found in sea 

 water and sediment from shallow depths to the deepest portions of the 

 sea. During the Danish Galathea Deep-Sea Expedition from 1950 to 

 1952, bacteria were found in depths as great as 10,280 meters." Many 

 of these bacteria have been found to be barophilic-^ growing exclusively 

 or preferentially at pressures approximating 15,000 psi. ZoBell and 

 Morita^" have reported experiments performed with these bacteria to 

 determine the effects of high pressure on such factors as viability and 

 enzyme production. Marine bacteria have been found capable of oxidiz- 

 ing rubber products,^^ as well as a wide variety of gaseous, liquid and 

 solid hydrocarbons.^'' Although evidence to date indicates that among 

 the microorganisms, the bacteria are particularly likely agents of de- 

 terioration in the ocean, it is possible that the fungi may also be con- 

 tributors. Barghoorn and Linder^^ report the physiological behavior and 

 growth on various media of seven species of marine fungi isolated from 

 wood continuously submerged in the sea. Deschamps-" has discussed the 

 role of fungi and bacteria in aiding the attack of wood by marine borers. 

 Also, the occurrence of marine fungi in wood test panels, driftwood and 

 piling in Biscayne Bay has been reported by Myers. ^^ 



A program designed to provide fundamental and engineering data on 

 the susceptibility of organic materials to marine borers and microorgan- 

 isms in an environment that covers about 70 per cent of the earth's sur- 

 face could be almost unlimited. The practical parameters which finally 

 were established were based on a number of considerations. Funda- 

 mental data on the basic inertness or relative rates of attack by micro- 

 organisms could best be determined under controlled laboratory condi- 

 tions; however, more than one procedure would be needed to determine 

 performance in the environments of water and sediment. Because of the 

 relatively rapid activity of marine borers under natural conditions, and 

 their critical requirements as far as laboratory culture is concerned, it 

 was decided that any borer tests would be conducted in the field. This 

 meant that the natural exposure tests would serve as correlative tests 



