The preferred location for the shallow-water exposure test would be in tropical 

 waters such as at Pearl Harbor, Hawaii, where the biological activity is intense. In 

 addition to the species of Teredo and Limnoria , a pholad, Martesia striata , is present 

 in these waters. Martesia striata is found throughout the world in nearly all temperate 

 and tropical regions and this invertebrate may prove to be the most destructive and 

 difficult to control of all the biological agents, especially since it is able to attack 

 various chemically preserved woods, hard tropical woods, and even solid lead sheaths 

 of submarine cables. Species of Martesia have been found in waters around the coasts 

 of North Carolina, Florida, Texas, Cuba, the Hawaiian Islands, Japan, the Philippine 

 Islands, and Australia. 



Commercially available plastic rods and tubes and other selected materials 

 will be exposed in the sea. The plastic rods will be assembled in a rack very similar 

 to the ones assembled for the deep-ocean exposure test. The lower ends of the rods 

 will be in marine sediments and the upper portions will be exposed to the sea water. 

 The rack with the test materials will be raised and inspected for any biological 

 deterioration after 6, 12, and 24 months' exposure in relatively shallow water. 

 Other selected engineering materials will also be exposed in this environment. 



Laboratory Investigations 



The Effects of Hydrostatic Pressure on Materials and their Resistance to 

 Biological Action . It is anticipated that some materials may undergo structural 

 changes under the influence of high hydrostatic pressure; i.e., changes in perme- 

 ability, density, elasticity, etc. Some materials which are normally resistant to 

 biological deterioration may become highly susceptible to biological action when 

 these changes take place. 



Hydrostatic pressures (up to 15,000 psi) will be applied to various organic 

 materials In a high-pressure test vessel. The biological-deterioration studies upon 

 these materials will take place In standard BOD bottles containing sea water and 

 bottom sediments and utilizing marine microorganisms as biological agents. This 

 laboratory test Is essentially a biochemical oxygen demand (BOD) type of test In 

 which the ability of marine bacteria to utilize organic compounds as the only source 

 of carbon for growth is determined. It is considered primarily a screening test. The 

 BOD-type test consists of two separate bioassay procedures. In one method, the 

 oxygen consumed by the aerobic bacteria is measured; in the other, a metabolic 

 by-product (hydrogen sulfide) resulting from anaerobic bacterial activity is measured. 

 With minor changes, the BOD-type test follows the procedures employed by Snoke32 

 In biological-deterioration tests of various organic materials and elastomers utilizing 

 marine microorganisms. 



15 



