to yield all the necessary information on the problem of biological deterioration of 

 materials in the deep ocean. Field, as well as laboratory, studies are essential. 

 The data obtained from these two approaches can then be compared and correlated, 

 and a more useful body of information on the behavior of each engineering material 

 to biological deterioration can be accumulated. This information would provide 

 marine engineers and designers with valuable data on the merits of each material 

 for use in the deep-sea environment. 



As a part of its total program of deep-ocean studies, the Laboratory is planning 

 a series of investigations along the following lines. 



Exposure of Materials in the Natural Sea Environment 



Deep-Ocean Exposure Test . Selected engineering materials to be exposed will 

 be secured aboard a Submersible Test Unit (STU), shown In Figure 2, and placed on 

 the bottom of the sea off Port Hueneme, California, at a depth of approximately 

 6,000 feet. For example, commercially available plastic rods and tubes will be 

 assembled in a rack as shown in Figure 3. A portion of each rod will be wrapped 

 with jute fiber and coal tar, another portion will be taped, and the remaining 

 area will be left smooth. At the midpoint of the rods, an untreated piece of pine 

 wood will be fitted around the test samples to act as bait to lure marine organisms 

 into direct contact with the specimens and thus determine whether or not they will 

 attack the plastic rods directly from the water. The assembled rack will be attached 

 to the STU In such a way that the lower ends of the rods will be buried in the bottom 

 sediments and the upper portions exposed to the sea water. This is to determine the 

 effect of mud dwellers, including bacteria, on plastics buried in the sediments, and 

 the effect of other marine organisms on plastic rods exposed above the mud line. 

 Various materials such as concrete, metals, rubber, electrical wire cables, and coral 

 concrete will also be placed aboard three STU's. The first STU will be retrieved 

 after 6 months, the second after 12 months, and the third after 24 months' exposure 

 in the deep ocean. The biological effects, if any, upon these materials then will 

 be carefully inspected and evaluated. Materials and devices placed on the STU by 

 other engineers and scientists for exposure to the effects of the deep-ocean environ- 

 ment will also be inspected for biological deterioration and any live specimens 

 found attached to these materials will be preserved for later biological study. 



Shallow-Water Exposure Test . Because of the wide differences in water 

 temperature, hydrostatic pressure, etc., between shallow and deep-ocean depths, 

 it is expected that the number, activity, and species of marine animals found will 

 be quite different in the two environments. However, it is possible that some species 

 which attack materials In shallow water may be eurybathic. A comparison of species 

 found deleterious to submerged materials (other than wood) in these two environments 

 will be made and the rates of deterioration due to biological action will be determined. 

 No further investigation other than the exposure test is planned in this environment. 



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